Adherence to evidence-based treatment guidelines for depression: a systematic review

Abstract

Background

Depression is a common mental disorder that has a profound impact on daily life and increases the risk of chronic diseases and mortality. Adherence to treatment guidelines would produce better patient outcomes but is often suboptimal. The objective of this systematic review was to examine adherence to evidence-based treatment guidelines for depression, identify factors that influence adherence and understand how to improve it.

Methods

We searched the PubMed, Web of Science and Cochrane databases. We included original trials, studies dealing with treatment-related guidelines and patients suffering from depressive disorders. We excluded reviews, study protocols and studies that dealt exclusively with mental disorders other than depression.

Results

85 studies met the inclusion criteria. Six studies focused on young subjects, three on the perinatal population and three on the elderly. A few studies concerned a population with somatic (n = 11) or psychiatric (n = 25) comorbidities. Eight articles focused on ethnic minorities.

Discussion

The lack of standard measurement on adherence and the variability in adherence rates highlight the complexity of assessing and implementing guideline-concordant care, and the associated challenges. Factors that influence adherence, such as those related to patients and their comorbidities, physicians, and guideline-related factors, play a significant role in determining whether appropriate treatment is received. Despite the complexity and cost of these strategies, multifaceted approach to guideline implementation, including the active involvement of clinicians, ongoing monitoring, and organisational support, improves guideline adherence.

Conclusion

This review provides a comprehensive overview of the current state of guideline adherence in treatment of depression and identifies areas for quality improvement initiatives.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12888-025-07192-6.

Background

Depression is a common mental disorder. An estimated 3,8% of the population suffers from depression, including 5% of adults. Depressive disorder can have a profound effect on all aspects of life, including performance at school, productivity at work, relationships with family and friends [1, 2]. Major depressive disorders increase the risk of developing other chronic disease, such as cardiovascular disease, metabolic syndrome and obesity and also increase the overall risk of mortality [3, 4]. Although clinical guidelines are available in many countries, the management of these disorders is often suboptimal and only limited numbers of patients have been reported as having received treatment in accordance with guidelines [5, 6]. There is evidence that adhering to treatment guidelines would produce better patient outcomes [7]. Thus, improving adherence to guidelines is an important public health objective.

Adherence to clinical guidelines is considered a key quality indicator in health care. However due to the complexity of clinical environments, reliable and sustainable quality of care improvements are difficult to implement [8]. According to the Institute of Medicine [9], clinical practice guidelines are defined as “systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances”. They serve as a framework to support consistent and standardised decision-making and promote quality and safety [9]. Guideline adherence denotes the degree to which healthcare professionals follow established guidelines, recommendations, or protocols when providing medical care to patients.

Adherence to guidelines involves following the recommended processes, procedures, or treatment plans outlined in the guidelines. It implies that individuals or organisations are implementing the prescribed actions and making choices that align with established standards. It is important because it helps ensure consistency, improve outcomes, and promote quality of care or performance [10].

Guideline adherence can be assessed through various methods, such as assessing compliance rates, tracking performance indicators, conducting audits, or evaluating outcomes. Adherence can vary depending on factors such as awareness of guidelines, availability of resources, organisational culture, individual attitudes and contextual factors [11].

Evaluation of guideline adherence may contribute to an improvement of structural and process quality, to the assessment of standards of practice and of health care staff, and the improved implementation of the guidelines themselves. This requires the definition of adherence criteria, i.e. the determination of the key elements or recommendations selected within the guidelines to assess adherence. Guidelines must be broken down into specific components, such as diagnostic criteria, treatment protocols, medication dosages, follow-up procedures, or preventive measures. These components will serve as the basis for assessing adherence.

However, it is important to note that guidelines are not meant to replace clinical judgment or individual decision-making but rather to provide a framework for informed decision-making based on available evidence and expert consensus [12].

The objective of this systematic review was to examine the measurement of adherence and of rates of adherence to evidence-based treatment guidelines for depression, to identify factors that influence adherence, to learn about the effects of adherence to guidelines and to understand how to improve it.

Methods

Search strategy

We conducted a systematic review concordant with Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations [13].

We searched the PubMed, Web of Science (WoS) and Cochrane databases limited search result to documents in the English or French language. No restrictions were applied regarding publication date.

To conduct the keyword search, we formulated the following search statement: (“guideline adherence” OR (“guideline” AND “adherence”)) AND (“depressive disorder” OR (“depressive” AND “disorder”)). The keywords were chosen in a non-restrictive way in order to identify the studies that correspond to the broad theme of our research.

Studies were screened based on their title and abstract, and the full text of potentially relevant articles was obtained for quality assessment and decision on inclusion in the final sample.

Furthermore, the references of each included article were screened following the same steps, which allowed for the identification of additional relevant studies. Identified publications were assessed by two reviewers who independently applied the predefined inclusion/exclusion criteria. All discordant assessments were discussed with a third reviewer until consensus was reached.

The review was not registered.

Inclusion and exclusion criteria

We included studies that met the following inclusion criteria: (1) original trials; (2) studies dealing with treatment-related guidelines of depressive disorder: (a) studies that measured adherence to treatment-related guideline of depressive disorders, (b) studies that identified factors that influence adherence to medication treatment-related guideline of depressive disorders, (c) studies that described the effect of adherence to treatment-related guideline of depressive disorders; 3) included patients suffering from depressive disorder. We excluded: (1) reviews; (2) study protocols; (3) studies dealing exclusively with guidelines for diagnosis or psychotherapeutic treatment or suicide; (4) studies dealing exclusively with guideline implementation; (5) studies of bipolar depression; (6) studies dealing exclusively with patients with mental disorders other than depressive disorders.

Data extraction and analysis

The data extraction was carried out by two reviewers who independently read the full-text articles. No automation tools were used. Data were grouped by both reviewers in an Excel table.

SD extracted the data and classified it into 4 subsets of interest validated by EH and HJ: 1) criteria used for measuring adherence to treatment-related guidelines; 2) adherence rates; 3) determinants of adherence; 4) impact of adherence and 5) strategies to improve adherence. We then analysed the data collected for each subset and ranked the complexity of the results obtained from our data analysis. To do this, we developed data classification grids for each subtype. This gave us a data tree structure. For the ‘adherence measurement’ subset, we classified the different measurement criteria into 14 indicator groups (see Sect. 3.2). For the “adherence rate” subset, we classified the data collected into: study types, time and place data, guideline sources, setting, population specificity and adherence rates. For the subset “determinants of adherence”, we classified the data into: patient-related determinants, clinician-related determinants, patient-pathology-related determinants and external factors (organisational and guideline-related). For the subset “impact of physician adherence”, we classified the impact as positive or negative. For the subset “strategies to improve adherence”, we classified interventions into: Combination of interventions, Use of reminders, Educational strategies, Mass media campaigns, Continuous quality improvement, Patient-mediated interventions, Task substitution, Financial interventions [14].

Risk of bias assessment (see additional file 1)

The ROBIS tool [15] was used to assess relevance, identify concerns with the review process and judge risk of bias in our review. ROBIS risk assessment showed high reliability of review results. Review process assessment revealed no problems and the review conclusions satisfactorily addressed the problems identified. The conclusions were supported by evidence and are commensurate with the relevance of the studies included.

Results

PRISMA selected studies

The systematic search yielded 533 articles, 313 of which were original published studies. Of these, 78 met the eligibility criteria, while seven additional studies were included based on references or websites (see the PRISMA - Preferred Reporting Items for Systematic reviews and Meta-Analyses - flowchart in Fig. 1). The total sample for review thus included 85 studies.

Fig. 1.

PRISMA flow diagram

Most of the included studies concerned the adult population, six studies focused on the young, three on the perinatal population and three on the elderly. Studies that included a population with somatic (n = 11) or psychiatric (n = 25) comorbidities assessed chronic obstructive pulmonary disorder (COPD) (n = 1), heart failure (n = 2), diabetes (n = 1), stroke (n = 1), cancer (n = 1), degenerative arthritis (n = 1), other somatic chronic disease (n = 4), substance use disorder (n = 2), attention deficit hyperactivity disorder (ADHD) (n = 1), post traumatic stress disorder (PTSD) (n = 1), eating disorder (n = 1) anxiety (n = 15), schizophrenia (n = 1), psychiatric disorders other than depression (n = 4). Eight articles focused on minority ethnic groups. Ten studies included veterans.

The professionals studied were general practitioners (GPs), psychiatrists or other specialists.

In line with the multidimensional aspect of guideline adherence by practitioners, studies were classified according to the dimension they evaluated. Five dimensions were identified for analysis: measurement of clinician adherence, adherence rates, determinants of adherence, the impact of adherence and adherence improvement strategies. When multiple criteria were applied by studies to the measurement of one or more dimensions, each criterion was treated independently.

Measurement of clinician adherence to guidelines (see Table 1 et2)

Table 1.

Multiple adhesion criteria

Study	Year	Country	Guideline	Patients and/or practitioners	Target discipline or setting	Measurement of provider performance	Type of study and intervention	Results
Aakhus [38]	2014	Norway	Norwegian national guideline	Interview: 4 elderly patients and 26 healthcare professionals; Survey: 129 healthcare professionals	Primary care (PC)	Adequate social contact, collaborative care plan, care manager, counselling, antidepressants (AD) in mild/severe/chronic depression	Interview and survey study	The most frequently identified factors of adherence were: dissemination of guidelines, time constraints, low prioritisation of elderly patients and patients wish for medication.
Alder [104]	2008	UK	Scottish postnatal depression guideline	15 National Health Service (NHS) Boards in Scotland and 199 general practices	National Health Service Boards and General Practitioners (GPs)	Adequate guidance for pregnancy and breastfeeding medication prescribing patterns	National survey study	Almost 50% of policies and 70% of GPs had implemented the majority of the guidelines.
Azocar [75]	2003	USA	National practice guideline	443 mental health clinicians, 836 patients	National Managed Behavioral Health Care Organisation	Objective measure: adequate medication evaluation, treatment initiation, treatment duration, depression and comorbidity documentation and subjective measure: suicide, substance abuse and medical and psychiatric comorbidities assessment, medication compliance, other clinicians informations, psychoeducation, treatment options and consent, treatment plan and goals and relapse and recurrence prevention	Randomised controlled-trial (RCT) of guideline dissemination	No effect of guideline dissemination.
Becker [36]	2011	USA	American Psychiatric Association’s (APA) evidence-based clinical practice guidelines	12671 individuals	Florida Medicaid population	Adequate AD dosage and adequate AD duration and approved combination of AD and adequate monitoring	Longitudinal retrospective study	Less than 30% of medication regimen were guideline adherent. Latinos were significantly more likely than Whites to receive guideline adherent treatment (58% vs 42%).
Bettinger [72]	2004	USA	Texas medication algorithm	8 staff psychiatrists and 1 nurse practitioner; 117 patients	Texas community mental health centers	Adequate AD and dosage and dosage increase and medication trial and provider contact	Retrospective study cross sectional	The average percentage adherence to the algorithm was near 75%.
Carson [33]	2011	USA	American Academy of Pediatrics treatment guideline	251 patients (88 Whites, 82 African-Americans, 81 Haïtians)	5 clinical sites in a community mental health system (specialised care (SC))	Adequate AD trial and duration	Retrospective chart review, cross sectional	Guideline-adherent treatment was received significantly more often by Whitepatients (45%) than for Haitians (16%) or African-Americans (24%).
Charbonneau [76]	2004	USA	Veterans Health Administration (VHA), Agency for Healthcare Research and Quality (AHRQ) and APA guidelines	12678 patients cared for at 14 VHA hospitals	VHA	Adequate AD dosage or duration	Observational study	Overall dosage adequacy was 90% and duration adequacy was 45%.
Chen [44]	2010	USA	APA and Agency for Health Care Policy and Research (AHCPR) guidelines	4102 patients	Large national health plan	Adequate duration of treatment in the acute and continuation phases or adequate follow-up	Retrospective cohort design using medical and pharmacy claims	Almost 50 % of patients received guideline concordant duration of treatment; patients who received adequate duration were more likely to receive guideline-concordant follow-up visits.
Datto [58]	2003	USA	AHCPR guideline	202 patients, 35 PC practices	PC practices randomized to telephone disease management (TDM) or “usual care” (UC)	Adequate treatment initiation and modification recommendation	Prospective study including 35 participating PC practices that agreed to be randomized to TDM or UC	Patients who received TDM were 7 times more likely to receive treatment in line with guidelines.
de Vries [110]	2016	The Netherlands	National practice and NICE guidelines	2942 patients between 6 and 17 years	A cohort of young people selected from a Dutch pharmacy prescription database	Adequate first AD prescription or adequate starting- and maintenance-dose	Retrospective prescriptions claims database study	First AD prescription was guideline-concordant less than 20 % of the time and starting doses were guideline-concordant 58 % of the time for children, 31 % for preteens, and 16 % for teens. Maintenance-dose were similar.
Dobscha [17]	2003	USA	VHA, APA and AHCPR/AHRQ guidelines	111 patients; 39 staff general internists, 6nurse practitioners, 2 physician assistants, and 39 internalmedicine residents	VA PC clinic	Adequate follow-up, initiate treatment plan, treatment preferences discussion, education	Medical record review pilot study	Less than 15% of patients were contacted for follow-up within 2 weeks, while 100% of providers documented follow-up plans to initiate treatment or to observe symptoms. Treatment preferences were discussed with 53% of patients, and 22% received education about depression.
Donohue [74]	2004	USA	APA and AHCPR guidelines	30621 patients	Medical and prescription drug claims database	Adequate AD initiation and dosage	Direct-to-consumer advertising (DTCA) and pharmaceutical promotion to physicians retrospective study based on treatment pattern examination from insurance claims	The likehood that a patient received an adequate AD initiation was significantly higher (32% higher relative odds) during periods when DTCA spending was in the top quartile.
Duhoux [6]	2008	Canada	Canadian guideline	1563 patients	Medical mental health sector, non-medical mental health sector or general sector	4 definitions: A = an AD + 4 visits or ≥ 12 visits, B = 4 visits, C = an AD + 4 visits, D = an AD + 4 visits or 8 mental health specialist visits	Cross sectional study	Average 50% (range, 48-71 %, depending on the definition of adherence) received guideline-concordant treatment.
Etchepare [29]	2016	France	French regulatory authority guideline	16144 subjects	the Echantillon Generaliste des Bénéficiaires (a permanent randomized representative sample of the beneficiaries of French health insurance)	Four binary criteria: 1 = type of antidepressant, 2 = visit, 3 = blood electrolyte monitoring, 4 = treatment duration	A historical fixed cohort study with dynamic follow-up time	Duration of AD treatment was compliant with guidelines for a minority of patients aged 65–74 years (13%), It slightly increased for patients aged 75 years and over (18%). Biological monitoring was also poorly in line with guidelines.
Fassaert [35]	2010	The Netherlands	Dutch college of GPs guideline	6413 patients	PC	Adequate follow-up, duration of treatment, referral to specialist	Longitudinal study	Less than half (43%) received guideline-concordant treatment. Only Surinamese/Antillean patients were less likely (32%) than ethnic Dutch to receive treatments according to guidelines.
Fedock [51]	2018	USA	APA/ American College of Obstetricians and Gynecologists guidelines	483 obstetric providers	Obstetrician gynecologists	Adequate AD prescription, arrange psychotherapy with a mental health provider and consult with a mental health provider	National random survey	The rate of guideline-compliant care was lower in pregnant than in postpartum patients (34% vs. 59%).
Fernández [30]	2006	Spain	NICE, APA, Royal Australian and New Zealand College of Psychiatrists guidelines	5473 subjects	PC vs SC	Minimally adequate treatment: Receiving pharmacotherapy for at least 2 months plus at least 4 visits with a psychiatrist, a GP or any other doctor; or at least 8 psychotherapy sessions with a psychologist or a psychiatrist	Cross sectional study	Similar proportions of patients in specialty and general medical sector received a minimally adequate treatment (about 30%)
Flanagan [69]	2009	USA	VHA guideline	129 VA medical centers and 2438 providers	VA medical centers	6 items included questions about knowledge, agreement, relevance, and clarity of the guideline. 2 items asked whether the implementation improved their knowledge and delivery of best practices related to the guideline.	Before/after national survey on the effectiveness of guideline implementation strategies on provider acceptance of guidelines	Provider adhesion increased with the number of implementation strategies of either type.
Forsner [111]	2008	Finland	Swedish clinical guideline	725 patient records were included, 365 before the implementation and 360 six months after.	4 psychiatric clinics	11 indicators including: treatment plan documented, antidepressant medication documented	Before/After active implementation observational study	Clinical guidelines for the treatment of depression was enhanced by an active implementation (90 vs 54 %).
Fortney [37]	2001	USA	AHCPR/AHRQ guidelines	106 patients	General medical or specialty mental health sector	Adequate dosage and duration of antidepressant and follow-up	Cross-sectional medical record review	Nearly 30% of the patients received guideline concordant treatment.
Gandjour [65]	2004	Germany	AHCPR/AHRQ guidelines	74 GP	PC	Adequate treatment, dosage and duration of AD	Retrospective multicenter observational study that assessed the costs and quality of treatment depression in England, Germany and Switzerland.	Insignificantly higher rate of patient received adequate treatment in Switzerland and England compared to Germany (56%, 52% and 35%, respectively).
Gaspar [84]	2019	USA	The National Committee for Quality Assurance’sAPA guideline	24579 patients	PC and SC	Adequate dosage, duration	Retrospective claims study	A minority of patients were adherent in the acute (42%) and continuation (32%) phases. Initial antidepressant dosages were not in line with guideline for 35% of patients. Most patients (55%) did not receive adequate treatment duration.
Hämalaien [23]	2009	Finland	Finnish national guideline	288 patients	Mental health or primary or secondary care services	Minimally adequate treatment: receiving AD pharmacotherapy plus at least four visits with a health care professional or informed psychological treatment and at least eight sessions with a health care professional	Comprehensive, multidisciplinary national population-based survey	Almost 20% received minimally adequate treatment.
Heddaus [54]	2018	Germany	German National Clinical Practice Guideline	569 patients	PC	Adequate treatment selection and initialisation	RCT: mild vs moderate vs severe depression	Selection and initiation of guideline-compliant treatment was highest for mild depression (91% vs. 85%). For moderate depression, guideline-compliant treatments were selected in 68% of cases and implemented in 54% of cases. Adherence to guidelines was lowest for severe depression (59% vs. 19%).
Heidari [66]	2017	Iran	Iran Community Mental Health Centers guidelines	3338 patients, 26 GPs	GP working with Community Mental Health Center	Adequate dosage and adequate medication	Retrospective observational study	86 % of patients received adequate treatment.
Henke [52]	2008	USA	AHCPR/AHRQ guidelines	353 patients, 76 clinicians, 28 practices	PC practices	Adequate follow-up, AD dosage and duration	Quality Improvement for Depression survey study	35 % of patients received adequate care.
Hepner [83]	2007	USA	AHCPR/AHRQ guidelines	1131 patients	45 PC practices	20 indicators including adequate AD initiation and duration	Observational analysis of data collected in 3 randomized clinical trials	Quality of care was high (nearly 80 % clinician adherence) for 6 indicators, including PC clinician detection of depression. Quality of care was low (adherence 20% to 38%) for 8 indicators, including treatment adjustment for patients who did not respond to initial treatment.
Hérique [112]	2009	France	French regulatory authority guideline	632 patients	PC	Adequate dosage and duration of AD	Retrospective cohort study	Treatments were adequate for only 40% of the SSRI and the SNRI patients and 20% of other AD.
Herzog [113]	2017	Germany	German National Clinical Practice Guideline, NICE and APA guideline	889 patients	Secondary analysis to the “RCT comparing an early medication change strategy with treatment as usual in patients with MDD"	Adequate treatment initiation, therapeutic drug monitoring, AD duration, dosage and change strategies	Naturalistic study	A large proportion of patients were not treated in adherence to treatment guidelines.
Ho [39]	2020	Malaysia	Malaysian Clinical Practice Guideline	112 general practitioners	GPs	Adequate duration of AD, anxiolytic	Survey research	Non adherence was highly significant (almost 60%).
Kasteenpohja [114]	2015	Finland	NICE, APA guidelines	142 young adults aged 19 to 34 years	Data were derived from the Mental Health in Early Adulthood in Finland study	Adequate duration of AD treatment, adequate follow-up and psychotherapy	National young adults survey	Almost 40 % of patients received minimally adequate treatment; and 15 % guideline-concordant pharmacotherapy.
Köhler [62]	2012	Germany	German guideline	224 patients	Psychiatric clinic	Adequate duration, dosage, combination of pharmacotherapy an psychotherapy	Naturalistic study (contribution to RCT)	70 % of patients were treated according to guidelines.
Kramer [24]	2008	USA	VHA practice guideline	208 patients	SC	Adequate AD prescription and follow-up	Observational study	Half received appropriate medication.
Kramer [115]	2003	USA	VHA practice guideline	109 patients	3 Department of VA medical centers	Adequate instauration, dosage, duration	Observational study	Half of depressed veterans received care consistent with clinical guidelines for psychopharmacological intervention.
Kurdyak [100]	2004	Canada	Canadian clinical practice guideline	278 patients	PC and SC	Adequate AD prescription and dosage	Cross-sectional study	Depressed persons with chronic medical conditions were significantly more likely to receive guideline-level care for depression (20%) than depressed persons without chronic medical condition (10%).
Lagomasino [31]	2005	USA	AHCPR/AHRQ guidelines	1175 patients; 46 managed PC practices	PC	Adequate AD prescription and follow-up	RCT: comparison Latinos care vs White care	Latinos were less than half as likely as Whites to receive guideline concordant care (19% vs 36%).
Latas [116]	2012	Serbia	National Serbian guideline	90 psychiatrists	SC	Adequate AD initiation, dosage, combination therapy, use of adjunctive anxiolytic treatment	Survey study	Psychiatrist’s preferences for themselves or their family members were mostly in accordance with guidelines.
Lin [73]	1997	USA	AHCPR/AHRQ guidelines	2657 patients; 22 primary care physicians	PC in a staff model health maintenance organisation	Adequate dosage and duration treatment	Before/after extensive physician education intervention study	44 % of patients in both the intervention and control clinics had adequate antidepressant therapy.
Massamba [117]	2017	Canada	Canadian National guidelines for seniors’ mental health	263 >65 older adults patients	PC	Adequate dosage, duration treatment and follow-up	Cross-sectional survey	44 % of patients received guideline concordant treatment.
McCarthy [118]	2007	USA	AHCPR/AHRQ guidelines	10545 patients	VA community-based outpatient clinics (CBOCs) or medical centers (VAMCs)	Adequate AD coverage, adequate follow-up	Observational study	Compared with patients diagnosed in VAMCs, those diagnosed in CBOCs were more likely to receive adequate antidepressant coverage (67% vs 65%).
Nazareth [49]	2002	UK	North of England evidence-based guidelines	75 GPs	GPs	Adequate knowledge and application of guideline (no further details)	Before/after educational outreach by community pharmacists RCT	After educational outreach, patients treated in accordance with guidelines increased slightly (4%).
Nease [70]	2008	USA	ND	Eighteen PC practices	PC	Adequate use of guideline (no more precision)	PC clinicians survey study to assess a modified improvement collaborative model	The modified improvement collaborative approach led to measurable improvements in use of depression guideline.
Olfson [119]	1998	USA	APA's practice guideline	189 psychiatrists	Psychiatrists	Adequate delay before declaring a medication trial succes or failure, adequate duration	Intention to treat survey	Nearly 85% of psychiatrists wait no more than 6 weeks before declaring the success or failure of a trial of medication; fewer (nearly 60%) keep first-episode patients on medication for at least 6 months.
Phipps [120]	2011	USA	FDA guidelines	151 Oncologists from nine children’s cancer centers	Oncology pediatry	Adequate antidepressant choice and monitoring	Multicenter survey study	A majority of oncologists (71%) reported prescribing SSRIs for their patients; only 28%reported monitoring patients on SSRIs at FDA recommendedintervals.
Prins [67]	2010	The Netherlands	Dutch college of GPs guideline	568 patients	PC	Receiving appropriate psychological support or counseling or appropriate antidepressant medication or a referral to a mental health special. Criteria for appropriate antidepressant medication were adequate AD initiation and adequate AD continuation-phase duration	Observational study	Almost 40% of patients received guideline-concordant care.
Roundy [41]	2005	USA	VHA practice guideline	102 patients	PC and SC	Adequate medication started, adequate starting dose and dose adjustment, adequate side effects information and assessment, monitoring and patient education	Retrospective chart review within the context of a RCT	Guideline supported treatment are more common in mental health car than in PC.
Schneider [57]	2005	Germany	APA and German guidelines	1202 patients	German psychiatric hospitals	Adequate general treatment strategy, AD prescription, AD dosage, benzodiazepine use	Multicenter study	Almost 80 % of the sample received adequate general treatment strategy, 90 % adequate AD prescription, 85 % adequate AD dosage, 15 % inadequate benzodiazepine use.
Scott [34]	2002	UK	AHCPR Depression Guideline	Practice A: 5435 patients; Practice B: 3250 patients	Two representative general practices that differed in resources available and populations served (practice A - privileged and B - deprived areas)	Adequate dosage, AD prescription	Prospective, before and after study of changesin detection and management following attempts tointroduce a chronic disease management approach.	Intervention reduced prescribing of sub-therapeutic doses of AD by 36%.
Sewitch [27]	2007	Canada	Canadian Network for Mood and Anxiety treatments guidelines	2742 patients	PC and SC	Adequate medication, starting dosage, and treatment duration	Retrospective cohort study	According to the 3 criteria, only 8% were treated appropriately (71% received a recommended first-line medication, 63% received a recommended starting dosage, and 15% received a recommended duration).
Shiner [43]	2014	USA	VHA practice guideline	532 patients	VAMC: 3 clinical settings: PC, the PC Mental Health Integration clinic and SC	Receiving appropriate psychological support or counseling or appropriate antidepressant medication or a referral to a mental health special. Criteria for appropriate antidepressant medication were adequate AD initiation and adequate AD continuation-phase duration	Before/after integration mental health study	The treatment provided in the integrated PC mental health clinic and the specialty mental health clinic is more in line with guidelines than in PC.
Smolders [53]	2009	The Netherlands	Dutch college of GPs guideline	721 patients	PC	Receiving appropriate psychological support or counseling or appropriate antidepressant medication or a referral to a mental health special. Criteria for appropriate antidepressant medication were adequate AD initiation and adequate AD continuation-phase duration	Cross-sectional cohort study	Almost 40 % of the patients with a depressive disorder was treated in accordance with the guideline.
Smolders [5]	2010	The Netherlands	Dutch college of GPs guideline	665 patients, 62 general practitioners from 21 practices	PC	Adequate treatment and adequate duration	Cross-sectional cohort study	Almost 20% was provided appropriate pharmacological treatment.
Wang [26]	2000	USA	AHCPR/AHRQ, APA guidelines	3032 patients	General medical sector, non-psychiatrist mental health specialty and psychiatrist sectors	Adequate AD prescription and follow-up	Cross-sectional survey	Almost 15% received consistent care. Among those with the most serious and impairing mental illness, a quarter received guideline-concordant treatment.
Watts [16]	2007	USA	AHCPR/AHRQ guidelines	Before: 320 patients, after: 350 patients	PC and SC	Adequate AD instauration date, dose and duration	Before/after the integration of a primary mental healthcare clinic (PMHC) into a large primary care clinic study	The PMHC model was associated with an increase in guideline-adherent depression treatment for depression (11% vs 1%) and with more rapid and improved treatment for depression.
Wiegand [42]	2016	Germany	German guideline	236843 patients	Psychiatric hospital, psychiatric specialist doctor and GP	Adequate AD, combination AD, long-term benzodiazepine treatment and provision of psychotherapy	Observational study	Patients treated by GPs received less often adequate medication and psychotherapy than patients treated by out-patient psychiatric specialists (almost 50 % vs 70%).
Yang [18]	2013	Korea	Korean Medication Algorithm	379 psychiatrists	SC	Adequate use of guidelines (not further specified)	Web-based survey study	Only 5% of psychiatrists reported using the guidelines exactly as written.

Table 2.

Single adhesion criterion

Study	Year	Country	Guideline	Patients and/or practitioners	Target discipline or setting	Measurement of provider performance	Type of study and intervention	Results
Baker [47]	2001	UK	England national practice guideline	64 GPs, 780 patients	PC	Adequate dosage	RCT of tailored strategies to implement guidelines	The proportion of patients receiving an adequate dose increases significantly with tailored implementation strategies.
Castro [58]	2015	Spain	Agència d’Informació, Avaluació i Qualitat en Salut, Barcelona (AIAQS), APA and National Institute for Health and Clinical Excellence (NICE) guidelines	212 patients in 3 primary care and 1 specialised care centers	PC and SC	Adequate duration of medication	Longitudinal study	Treatment adequacy of depressive disorders was higher in SC (95%) than in PC (80%).
Chen [121]	2001	USA	AHCPR guideline	208 patients	Veterans Affairs Medical Center (VAMC)	Adequate dosage	Cross sectional study	Almost 90% received dosages within the recommended range.
Coughlin [32]	2021	USA	American College of Physicians and VHA clinical guidelines	53034 patients	VHA	Adequate duration of treatment in the acute and continuation phases	Retrospective cohort study	Acute- and continuation-phase AD treatment was provided to 59% and 36%, respectively, of those with co-occurring substance use disorder and depression, compared with 66% and 44%, respectively, of those without substance use disorder.
Crown [22]	2001	USA	WHO and AHCPR guidelines	2030 patients	PC and SC	Adequate duration of treatment in the continuation phase	Retrospective study using medical and prescription claims databases	Patients who were initially prescribed fluoxetine were more likely than sertraline or paroxetine to receive guideline concordant treatment (almost 60 % vs 50%).
Fujita [122]	2008	Japan	AHCPR/AHRQ guidelines	95 patients	23 psychiatric departments	Adequate dosage	Naturalistic prospective follow-up observational study	A minority of patients were prescribed inadequate dose, both during continuation (about 25%) and maintenance phase (around 15%).
Gallimore [77]	2013	USA	Unity Health Insurance guideline	95 patients	PC	Adequate follow-up	Before/after telephone follow-up monitoring study	The rate of patients receiving adequate follow-up significantly increased from 7% to 24% after implementation of the monitoring protocol.
Hoffmann [123]	2012	Germany	German, UK and US guidelines	4,295 patients	PC and SC	Adequate prescription of antidepressant	Cross-sectional study of claims data	Almost 25% of patients treated with AD received fluoxetine.
Horgan [55]	2008	USA	APA practice guidelines	361 health plan products on antidepressant medication management	PC and SC	Adequate duration of treatment in the acute and continuation phases	National survey	60% of concordance for effective acute-phase treatment, 43% for continuation-phase treatment.
Jordan [45]	2007	USA	APA Practice guideline, National Committee for Quality Assurance antidepressant medication management, VHA practice guideline	5,517 veterans with COPD that experienced a new treatment episode for major depressive disorder	PC and SC	Adequate duration of antidepressant medication	Retrospective cohort study	Half of patients had guideline-concordant antidepressant coverage.
Katon [59]	1995	USA	AHCPR/AHRQ guidelines	217 patients	PC in a staff model health maintenance organisation	Adequate dosage	RCT: comparison increased primary-care access plus specialty consultation versus usual care	In patients with major depression, the intervention group had greater adherence (75% vs 50%). In patients with minor depression, the intervention group had greater adherence than the usual care (80% vs 40%).
Lai [124]	2011	Taiwan	Department of Health, Taiwan (2004) guidelines for benzodiazepine using in sedation and hypnosis.	5463 prescriptions of benzodiazepines solely used for major depressive disorder	General sector	The proportions of major depressed patients who were prescribed at least one benzodiazepine without any AD	Before/after implementation ofguidelines for benzodiazepine use study	The implementation of the benzodiazepines guidelines was not associated with a reduced rate of sole prescribing of benzodiazepines for major depression.
Melfi [61]	1998	USA	AHCPR/AHRQ guidelines	4052 patients	PC and SC	Adequate duration of treatment in the acute and continuation phases	Cross-sectional database review of Medicaid claims records	Fewer than 30% of the antidepressant users received treatment minimally consistent with guidelines.
Miranda [63]	2004	USA	AHCPR/AHRQ guidelines	1356 patients	Six managed care organisations PC	Adequate treatment	RCT: minority vs nonminority patients	A third of the minority patients and just over half of white patients were getting appropriate care by 6 months.
Nau [64]	2005	USA	AHCPR/AHRQ guidelines	1454 patients	Managed care organisation	Adequate duration of ad medication	Retrospective study of medical/pharmacy claims data	50% were in concordance with the acute phase treatment guidelines.
Piek [28]	2014	The Netherlands	Dutch college of GPs guideline	1571 observations of remitted depression	General practice	Adequate maintenance treatment duration	Observational study	Patients often do not receive adequate maintenance treatment. This is more frequent for older patients, patients with a lower education, those using benzodiazepines or receiving psychological/psychiatric care and patients with a concurrent history of a dysthymic or anxiety disorder.
Richardson [125]	2004	USA	The Health Plan Employer Data and Information Set (HEDIS) quality-of-care guidelines for depression	1205 patients	The Washington State Medicaid program included outpatient and inpatient health care and mental health care	Adequate duration of treatment	Observational study	A quarter of patients received at least 6 months of treatment as recommended by the HEDIS criteria.
Rollman [71]	2001	USA	AHRQ guideline	212 patients	PC	Adequate AD initiation	RCT	Electronic medical Record improve guideline adherence
Salter [25]	2012	Canada	Canadian best practice recommendations regarding assessment and management of poststroke depression	123 patients	Specialised stroke rehabilitation unit	Adequate AD prescription at discharge	Practice audit by chart review	One third of patients had been prescribed antidepressants at discharge.
Schulberg [126]	1995	USA	AHCPR Depression Guideline	91 patients	PC: Ambulatory family health centers and internal medicine clinics	Adequate duration of treatment in the acute and continuation phases	Prospective cohort study	One third of patients received guideline concordant treatment.
Shiner [127]	2010	USA	FDA and APA guidelines	51 patients	Resident psychopharmacology clinic	Adequate antidepressant trial	Before/after quality improvement program study	The program has improved the compliance of prescriptions with guidelines.
Simmons [60]	2016	Australia	Australian clinical practice guidelines for the treatment of youth depression	66 patients	2 enhanced PC services	Adequate treatment choice	Before/after online decision aid uncontrolled cohort study	After using the decision aid, clients were more likely to make a decision in line with guideline recommendations.
Sood [20]	2000	USA	APA guidelines	2917 patients	Medical and prescription claims database	Adequate duration of treatment	Retrospective study using medical and prescription claims databases	Patients initially treated with tricyclics or sertraline were more likely to receive guideline adherent treatment than those initially treated with fluoxetine. Guideline accordant treatment was associated with reduced likelihood of relapse or recurrence of depression.
Stiles [55]	2009	USA	APA guideline	475 patients	3 Medicaid financing arrangements: FFS: fee-for-service; PMHP: prepaid mental health program; HMO: HealthMaintenance Organization.	Adequate treatment	Cross-sectional survey comparing 3 financing conditions	Individuals in the FFS condition and in the non-acute severity depression group were more likely to receive adequate mental health treatment.
Tamburrino [46]	2011	USA	AHRQ guidelines	148 patients	PC	Adequate medication change	Observational study	About 30% of depressed patients received guideline concordant change treatment.
Tiemeier [40]	2002	The Netherlands	Dutch national guidelines	264 GPs, psychiatrists, psychotherapists, and clinical psychologists	A random sample from four professional groups in the Dutch mental healthcare system	Adequate treatment	Intention to treat population survey	Almost 70 % of all intention-to-treat decisions were consistent with the guidelines.
Tournier [21]	2010	France	International practice guideline for AD treatment	35 053 patients	PC and SC	Adequate duration of treatment	Retrospective cohort study	Almost 20% of the patients received adequate duration of treatment.
Van Fenema [128]	2015	The Netherlands	Dutch association of psychiatry guidelines for diagnosis and treatment of psychiatric disorder	5346 patients	Routine Dutch clinical outpatient setting for common mental disorders (secondary mental health care)	Adequate duration of treatment	Retrospective cohort study	For patients receiving pharmacotherapy, alone or as combination therapy, treatment duration was adequate in majority of the cases. This rate decreases for patients receiving only pharmacotherapy.
Wheeler Vega [129]	2002	UK	British National Formulary and consensus guidelines	494 patients	Community and acute care units in a National Health Services Trust	Antipsychotic prescription without any recognised indication	Trust wide audit	More than a quarter of the sample were prescribed an antipsychotic; 40 % of these received an antipsychotic without any recognised indication.

Practitioner adherence to depression medication guidelines was able to be assessed through several indicators to evaluate how healthcare providers followed evidence-based guidelines for depression management with medication. These indicators helped measure the appropriateness, safety, and effectiveness of medication prescribing practices. Most of the studies defined rules based on a list of criteria, such as quality indicators or simply a list of items to be checked for adherence. Most studies used several different criteria to assess adherence (n = 56) (see Table 1), while a smaller proportion used only one criterion (n = 29) (see Table 2). A few publications defined a single rule based on a list of criteria, with one measure per criterion (n = 23). In other studies, adherence was measured using a composite score of different adherence criteria (n = 30). Some studies did not provide a clear definition of the rules for determining adherence to clinical guidelines (n = 3).

Indicators for assessing practitioners’ adherence to depression medication guidelines are listed below in descending order of number of occurrences. Those appearing most frequently were (n = number of studies identified, concerned by this indicator):

• Duration of treatment (n = 47): this indicator measured the length of time patients receive medication treatment for depression. Adherence involved ensuring that patients received an adequate duration of treatment, typically several months, to achieve optimal outcomes and prevent premature discontinuation.

• Initial treatment choice (n = 33): this indicator assessed whether practitioners prescribe psychotherapy or antidepressant when depression was identified.

• Adequate dosage or dose optimisation (n = 28): this indicator evaluated whether practitioners titrated medication doses to achieve therapeutic levels based on patient response and tolerability. Adherence involved adjusting medication doses as needed to optimise treatment effectiveness while minimising side effects.

• Monitoring for therapeutic response (follow-up visits) (n = 28): this indicator assessed whether physicians monitored patients regularly for therapeutic response to medications. Adherence involved assessing improvement of symptoms and adjusting treatment as needed based on ongoing monitoring.

• Initial medication choice (n = 25): this indicator assessed whether physicians used the recommended first-line medications for depression, such as selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs), as initial treatment options.

Those occurring less frequently are:

• Referral to specialised care (n = 12): this indicator assessed the appropriateness and timeliness of referrals to mental health specialists for patients with complex or treatment-resistant depression. Adherence involved recognising when specialised care was necessary and making timely referrals.

• Change strategy, combination treatment (n = 12): this indicator assessed whether changes or drug combinations were implemented according to the rules (switch) and whether the choices of drug combinations or potentiations were approved by the recommendations.

• Patient education (n = 8): This indicator assessed the extent to which practitioners provided education to patients on their prescribed medications, including potential benefits, risks and side effects. Adherence involved ensuring patients had accurate information about their medication regimen and understood it.

• Avoidance of polypharmacy (n = 5): this indicator evaluated whether practitioners avoided unnecessary or excessive use of multiple psychotropic medications concurrently. Adherence involved minimising polypharmacy by utilising evidence-based guidelines that emphasised the use of monotherapy when appropriate.

Followed by those rarely used:

• Side effect monitoring and management (n = 3): this indicator measured the extent to which practitioners monitored and managed medication-related side effects. Adherence involved the regular assessment of side effects, discussion of potential side effects with patients, and implementation of strategies to manage or alleviate them.

• Treatment options/preferences (n = 2): using a survey sent to clinicians or information recorded in a computerised patient record system, this indicator subjectively measured the treatment options proposed by clinicians, patients’ treatment preferences and the demand for consent to treatment.

• Adherence assessment (n = 2): this indicator measured whether healthcare providers regularly assessed and addressed patient adherence to prescribed medications. Adherence involved identifying barriers to adherence and implementing strategies to improve patient compliance.

• Regular medication reviews (n = 2): this indicator evaluated whether practitioners conducted regular reviews of patients’ medication regimens, considering the need for continuation, adjustment or discontinuation of medications. Adherence involved reviewing the appropriateness and safety of medication over time.

• Documentation of medication management (n = 2): this indicator assessed the completeness and accuracy of documentation related to medication management, including medication choices, dosage and monitoring. Adherence involved maintaining thorough and up-to-date documentation of medication management decisions and outcomes.

Adherence rates (see Table 1 and 2)

Types of studies identified

The search identifies 85 depression guidelines adherence studies, which could be classified into four categories: observational studies (n = 49), survey studies (n = 18), before/after studies (n = 10), randomised controlled trials (RCT) (n = 9). In 29 studies, a single criterion was used to assess adherence, while in 56 studies, multiple criteria were used to assess adherence.

Time and place data

Studies were published between 1995 and 2020, ¾ of them between 2000 and 2014. 52% of the studies were carried out in the United States (44/85), eight in The Netherlands, seven in Germany, five in Canada and in the United Kingdom, three in Finland and in France, two in Spain and one in each of the remaining countries.

Guideline sources

The guidelines on which studies were based are international (n = 22), national (n = 60) or regional (n = 3). Many studies refer to Agency for Health Care Policy and Research now the Agency for Healthcare Research and Quality, AHCPR/AHRQ primary-care depression guidelines (n = 25). Nine studies involved the Veterans Health Administration Office of Quality and Performance Clinical practice guideline for major depressive disorder.

Setting studied

24 studies were conducted in primary care. 17 were conducted in primary care and secondary care. 16 were conducted in secondary care (mental health sector or another specialised care sector). 10 were carried out in Veterans Affairs medical centres. This was not specified in the other studies.

Adherence rates

Of the 85 included, 64 provided quantitative adherence rates. The other 21 were qualitative or dealt with increasing or decreasing rates. These 64 studies displayed a wide range of adherence rates. Overall, adherence rates vary from 1% [16] to 100% [17]. 90% of the 64 quantitative studies reported at least one adherence rate below 75%. The two lowest adherence rates were based on the measurement of several compiled criteria of adherence to recommendations [16, 18]. The two highest adherence rates were related to the measurement of a single criterion: adequate antidepressant treatment duration [19] or adequate treatment initiation plan [17] in the mental health sector. Results of before/after studies could be categorised as positive or negative based on whether the intervention group had higher adherence rates than the comparison group. Eight of the ten before/after studies had positive results, and showed better rates in intervention groups than in control groups. RCT studies on improvement strategies have also shown predominantly positive results.

Determinants of adherence to depression guidelines

Patient-related factors

Gender.

In almost all studies, female gender was associated with stronger adherence to depression guidelines [20]. Women were associated with a statistical difference regarding receipt of an adequate duration of antidepressant medication: filling at least six prescriptions in the six months following the index date [21], filling at least four prescriptions in the six months following the index date [22]. Being female increased the probability of receiving antidepressant treatment [23]. For adolescents, the mean score for quality of care (including receiving SSRI and an adequate duration of antidepressant treatment) was significantly higher for females compared with males [24]. Prescription of antidepressants for post-stroke depression on discharge from rehabilitation was significantly higher in females than in males [25]. Another study showed that being female was a predictor of receiving guideline-concordant care in the specialty mental health sector, but not in the general medical sector [26]. In contrast, women were less likely than men to receive the recommended first-line drug therapy, even though they were more likely to receive psychoactive medication [27].

Age.

Older patients were more likely to receive prescriptions within guidelines [20, 22]. Increasing age led to more maintenance treatment [28]. Duration of guideline-compliant treatment was associated with age. When age increased by ten years, the rate of duration of guideline-compliant treatment increased by 13% [21]. Moreover, in the study of Etchepare et al., treatment duration and antidepressant type selection were more frequently adequate in people aged 75 years and over than in those aged 65–74 years [29].

Education.

People with a high level of education were more [30] or less [28] likely to receive guideline-compliant treatment.

Ethnicity.

In general, racial and ethnic minorities and those experiencing homelessness had lower odds of receiving guideline-concordant antidepressant treatment [26, 31–33]. Furthermore, in the study of Scott et al., a multifaceted approach failed to affect depression management in a less well-resourced practice serving large ethnic minority populations, while it improved depression management in a practice serving a predominantly affluent white British population [34]. A study showed subtle differences: among different ethnic groups (Turkish, Moroccan and Surinamese/Antillean), only Surinamese/Antillean patients were less likely than ethnic Dutch to receive treatments according to guidelines [35]. Conversely, Becker et al. found that Latinos adults were more likely than White adults to receive guideline-adherent treatment [36].

Place of residence.

Compliance for duration of treatment and for selection of the antidepressant type was higher in persons living near a university hospital [29]. Living in a large city was either significantly related to treatment adequacy [30] or, in contrast, to treatment inadequacy [6, 32]. Travel time was a significant predictor of receiving guideline-concordant care: decreasing travel time to the preferred provider by 60 min was said to multiply the odds of receiving guideline-concordant care by three and a half times [37].

Health insurance.

Possession of insurance coverage was a factor associated with receiving guideline-consistent care in both the general medical sector and the specialty mental health sector [26]. Guideline-compliant treatment duration was associated with an absence of universal health coverage [21].

Internal factors.

Other patient-related factors were able to influence guideline compliance, such as patient expectations, negative reactions, low self-esteem, lack of information regarding the effect of the antidepressant [38], non-compliance with treatments [39], lack of socio-economic resources [34, 40], and highly health self-esteem [30].

Physician-related factors

Medical Specialty.

Guideline adherence was better in psychiatrists and the mental health care sector compared with GPs or the primary care sector. In thirteen studies, patients monitored in primary care were less likely to have guideline-adherent care, compared with those who received care in the mental health sector or who were comanaged by mental health care providers [6, 19, 21, 23, 28, 29, 40–45],. Tamburrino et al. showed that about 70% of patients followed in primary care did not have their medication changed during a 12-week window in which such changes would be expected [46]. In the study of Crown et al., the probability that patients would be guideline-adherent was reduced when a family practitioner was the provider [22]. Moreover, GPs who collaborated with professionals specialised in mental health care treated their patients more often in accordance with the guidelines than did GPs who did not collaborate with mental health specialists [47]. In contrast, in the study of Etchepare et al. patients aged 75 years and over were less likely to receive the appropriate type of antidepressant when prescribed by a private psychiatrist [29]. For patients with COPD and comorbid depression, being seen in pulmonary care settings (like being seen in a mental health clinic) also increased the odds of receiving guideline-concordant care compared to primary care only [45].

Personal factors of physicians.

The barriers mentioned as being personal factors of physicians could be divided into factors related to physicians’ knowledge and physicians’ attitudes [48]. In terms of physicians’ knowledge, lack of awareness, training and familiarity with guidelines contributed to failure to adhere to guidelines [18, 25, 38, 39]. With regards to attitudes, the main factors associated with non-compliance with guidelines was disagreement (physicians may not have agreed with a specific guideline or the concept of guidelines in general) [18, 47, 49], self-efficacy [5, 39, 47, 50], skills [38, 39, 51, 52] and motivation [47, 49, 51, 52]. Psychological conditions such as emotional fatigue or depression were also associated with reduced adherence to guidelines [39, 47].

Patients pathology-related factors

Adherence to depression guidelines was improved, when the practitioner made the diagnosis and recorded it [53] and when chronic illness [29] or long-term condition depression status was recognised [21].

Severity of symptoms.

Patients with more severe disease received more guideline-compliant treatment [22, 23, 25, 26, 28, 40, 54]. Patients without the classical description of depression, neurotic depression or psychotic depression was less likely to receive adequate treatment [22, 39, 40].

Comorbidities.

Having chronic medical comorbidities, either psychiatric or somatic, was most often associated to guideline-compliant treatment. Conversely, psychiatric and medical comorbidities were associated with lower odds ratio of receiving guideline-concordant depression treatment [22, 24, 32]. Alcohol, opioid and cannabis use disorders were all associated with lower odds of adequate acute-phase antidepressant treatment [32, 40]. Alcohol and cannabis use disorders were also associated with significantly lower odds of adequate continuation of antidepressants treatment [32].

Antidepressant type.

The choice of initial antidepressant drug affect adherence to treatment guidelines: patients with fluoxetine had the highest probability of receiving antidepressant medication according to guidelines [6, 20, 22]. Greater access to SSRIs is associated with higher a probability of receiving appropriate treatment [50].

External factors - organisation-related factors

Organisation-Related Factors.

Organisational constraints are of major importance [49]. The care setting must be considered during the development of a guideline [39, 50, 53]. The incorporation of guidelines in a quality management [18] may improve adherence. A shortage of resources, associated with, for example, time restrictions [5, 38, 39, 51], financing condition [50, 55] and a heavy workload leading to failure to prioritise depression [38, 51] are well established barriers to guideline implementation in practice. A multiprofessional collaboration with other healthcare professionals may increase guideline adherence [18, 38, 50].

Guidelines.

The main barriers to guideline adherence were related to the process of developing and establishing a guideline [56]. Lack of evidence [47, 49] and the plausibility [38] of recommendations were important factors involved in non-adherence. Furthermore, complexity, layout [18] and accessibility [18, 38] must be considered.

Impact of clinician adherence with guidelines (see Table 3)

Table 3.

Impact of clinician adherence with guidelines

Study	Year	Effect	Results
Prins [67]	2011	none	The added value of guideline concordant care could not be demonstrated in this study
Gandjour [65]	2004	negative	Increases costs
Heidari [66]	2017	negative	Reduces continuity of care
Prins [67]	2010	negative	Increases depression costs
Stiles [55]	2009	negative	Increases mental health costs and total social costs
Stiles [55]	2009	negative	Reduces less mental health symptoms
Crown [22]	2001	positive	No higher costs
Datto [58]	2003	positive	Improves depression outcome
Fortney [37]	2001	positive	Improves depression severity but not with improvements in overall mental or physical health
Köhler [62]	2011	positive	Decreases depressive symptoms
Melfi [61]	1998	positive	Reduces the probability of relapse or recurrence
Miranda [63]	2004	positive	Reduces depression in both minority and non-minority populations
Miranda [63]	2004	positive	Increases employment in minority ethnic groups
Nau [64]	2005	positive	Improves adherence to associated antidiabetic therapy
Schneider [57]	2005	positive	Improves response to treatment
Sewitch [27]	2007	positive	Decreases risk of hospitalisation
Simmons [60]	2016	positive	Reduces depression symptoms
Sood [20]	2000	positive	Reduces the likelihood of relapse or recurrence of depression
Yang [18]	2013	positive	Helps in clinical decision making
Yang [18]	2013	positive	Provides informative resources for the patients and their caregivers
Katon [59]	1995	positive	Improves depression outcome in patients with major, but not minor, depression

Clinician adherence to depression treatment guidelines can have significant implications for patient outcomes, healthcare costs, and overall quality of care. It has both positive and negative implications.

Positive impacts

Improved patient outcome

Three randomised controlled trials, four cross-sectional studies, a before and after study, a multicenter study and a quasi-experimental study were identified that investigated the impact of practice guidelines on clinical outcome. Adherence to depression guidelines ensured that patients received evidence-based and effective treatments [57], leading to better depression outcome [58, 59], fewer depressive symptoms [60], mitigation of depression severity [37] and reduced probability of relapse or recurrence [20, 61, 62]. Evidence-based care for depression was equally effective in alleviating depressive disorders for minority and nonminority patients [63].

Enhanced quality of care

Adherence to guidelines led to improved quality of care. Providing guideline-compliant antidepressant treatment to patients with other comorbidities improved the quality of care for these comorbidities. Indeed, Nau et al. had shown that administering guideline-compliant antidepressant therapy to diabetic patients could help maintain an appropriate use of diabetes medications [64]. Furthermore, Sewith et al. observed that guideline concordance was associated with a lower risk of hospitalisation [27].

Enhanced provider performance

It is evident that following guidelines helps to enhance provider performance. Following guidelines supports continuous professional development by ensuring that clinicians stay up-to-date on the latest evidence-based practices and encourages collaboration among healthcare professionals [18].

Public health impact: reduced burden on society

Effective depression management helps to reduce the overall burden of the disease on society, including loss of workplace productivity [63].

Cost-effectiveness

Effective, guideline-based treatment of depression does not result in increased healthcare costs associated with the correct use of antidepressants [22].

Negative impacts

Conversely, other studies showed increased costs when patients received guideline-concordant treatments [55, 65]. In addition, adherence to guidelines may have other negative effects such as decreased reduction of mental health symptoms [55], decreased continuity of care [66] or no effect at all [67].

Strategies to improve clinician adherence (see Table 4)

Table 4.

Strategies to improve clinician adherence

Study	Year	Type of strategie	Improvement strategies	Outcome Measures	Target public	Number of practitioners or care centers	Number of patients	Effectivness
Bootsmiller [68]	2004	Combination of intervention	Forms to support guideline adherence; Computer-interactive educational programs; Internet discussion groups; Responsibilities of non physicians changed to support guideline adherence; individual visit providing research results (academic detailing).	Assessment of clinical practice guideline implementation methods used in VAMCs and comparison of strategies used in the VAMC with those methods found to be effective in the literature.	Providers	123 VAMCs	ND	Consistently effective: the frequent use of consistently effective approaches and multiple approaches benefits adherence.
Baker [47]	2001	Combination of intervention	Tailored methods to overcome obstacles to change using psychological theories.	Record of adherence to guideline recommendations; proportion of patients with Beck Depression Inventory score.	GPs	34 GPs	197	Effective
Flanagan [69]	2009	Combination of intervention	Provider-focused strategies.	Six items assessed provider’s acceptance about knowledge, agreement, relevance, and clarity of the guidelines.	Providers	2438 providers and 242 quality managers from 129 VAMCs	ND	Effective
Katon [59]	1995	Combination of intervention	Multifaceted intervention: collaborative management by the primary care physician and psychiatrist, intensive patient education and ongoing monitoring.	Short-term (30-day) and long-term (90-day) use of antidepressant medication at guideline dosage levels, satisfaction of patients and reduction in depressive symptoms.	Patients and primary care physicians	22	108	Effective
Nease [70]	2008	Combination of intervention	Collaborative approach to improvement: change management strategy taught in learning and instruction sessions in a step-by-step process to improve depression care.	Nine-item Patient Health Questionnaire: screening, diagnosis, surveillance, tracking and management; pre- and post-intervention depression care survey data.	Practitioners	18 practices (9 internal medicine and 9 family practices)	ND	Effective
Bettinger [72]	2004	Educational strategie	Texas Implementation of Medication Algorithm: one-day training session.	Documentation of outcome measures, prescribing patterns (correct medications, therapeutic dosing, dosage increases and appropriate medication changes), and visit frequency.	Clinicians	8 staff psychiatrists and 1 nurse practitioner	117	Effective
Donohue [74]	2004	Mass media campaign	Direct to consumer advertising including print, radio, and television advertising.	Initiation of antidepressant use within 60 days of the episode start date and appropriate duration of antidepressant treatment.	Consumers or physicians	ND	30,621	Effective
Datto [58]	2003	Patient-mediated intervention	Telephone disease management program.	Treatment recommendations made by providers.	Patients	ND	61	Effective
Simmons [60]	2016	Patient-mediated intervention	Online decision aid with evidence communication, preference elicitation and decision support components.	Ability to make a decision; whether the decision was in line with clinical practice guidelines, personal preferences and values; decisional conflict; perceived involvement; satisfaction with decision; adherence; and depression scores at follow-up.	Patients and clinicians	23 clinicians	66, aged 12–25 years	Effective
Flanagan [69]	2009	Reminder and computer use	Workflow-focused strategies.	Six items assessed provider’s acceptance about knowledge, agreement, relevance, and clarity of the guidelines.	Providers	2438 providers and 242 quality managers from 129 VAMCs	ND	Effective
Gallimore [77]	2013	Substitution of task	Multidisciplinary telephone follow-up protocol.	Percentage of patients who achieved 3 follow-ups within 12 weeks of antidepressant prescription.	Patients	ND	50	Effective
Shiner [127]	2010	Total quality management	Quality improvement program with administrative process changes.	Timely follow-up, adequate trial, adequate improvement and made indicated change in medication.	Psychopharmacology clinic	12 residents, 4 psychiatrists	187	Effective
Watts [16]	2007	Total quality management	Quality improvement project integrating mental health into primary care.	Proportion of patients receiving depression treatment and guideline-adherant depression treatment, number of patients seen in mental health clinics and waiting times before being seen by mental health staff.	Primary care	ND	383	Effective
Lin [73]	1997	Educational strategie	Physician education.	Antidepressant medication selection, adequacy (dosage and duration) of pharmacotherapy, intensity of follow-up, physician delivered educational messages regarding depression treatment, patient satisfaction and depression outcome.	Primary care physicians	22	ND	Effective for program period only, but no enduring effect.
Scott [34]	2002	Combination of intervention	Multifaceted intervention: resources to develop a case register, education and training program, facilitation of meetings with secondary care and support in developing a practice guideline.	Rates of cases prescribed SSRIs, subtherapeutic doses of antidepressants, rates of new cases reviewed within 6 weeks or referred to mental health services.	Primary care physicians	ND	337	Effective, but this model failed to affect depression management when staff engagement with the project was passive rather than active and the practice was less well-resourced and served an economically deprived and ethnically diverse population.
Bootsmiller [68]	2004	Educational strategie	Providers received a brief guideline summary (algorithm, key points) Providers received a copy of complete guideline Providers received a pocket card summarizing key points Storyboards regarding this guideline posted in clinical areas Instructional audio/video tape regarding this guideline Grand rounds presentations	Assessment of clinical practice guideline implementation methods used in VAMCs and comparison of strategies used in the VA with those methods found to be effective in the literature.	Providers	123 VAMCs	ND	Minimally effective
Rollman [71]	2001	Reminder and computer use	Electronic medical record.	Depression severity, quality of life, perceived social support, type of depression treatment recommended at the instauration, number and timing of follow up visits, physician knowledge and attitude toward treating depression.	Primary care physicians	16	212	No effect, but promising.
Donohue [74]	2004	Financial intervention	Free samples of drugs left with physicians.	Initiation of antidepressant use within 60 days of the episode start date and appropriate duration of antidepressant treatment.	Consumers or physicians	ND	30,621	Not effective
Azocar [75]	2003	Mass media campaign	General mailing of guidelines to clinicians.	Percentage of patients receiving: (1) medication evaluation, (2) psychotherapy, (3) both medication and psychotherapy, (4) continuation treatment, (5) documentation of a mental health or substance abuse comorbidity, and (6) documentation of medical conditions; clinicians subjective measure by using a 13-item adherence checklist.	Mental health clinicians	443	836	Not effective
Donohue [74]	2004	Mass media campaign	Detailing to physicians.	Initiation of antidepressant use within 60 days of the episode start date and appropriate duration of antidepressant treatment.	Consumers or physicians	ND	30 621	Not effective
Azocar [75]	2003	Patient-mediated intervention	Mailing in which guidelines were targeted to a patient starting treatment with the clinician.	Percentage of patients receiving: (1) medication evaluation, (2) psychotherapy, (3) both medication and psychotherapy, (4) continuation treatment, (5) documentation of a mental health or substance abuse comorbidity, and (6) documentation of medical conditions; clinicians subjective measure by using a 13-item adherence checklist.	Mental health clinicians	443	836	Not effective
Charbonneau [76]	2004	Total quality management	Implementation of continuous quality improvement.	Antidepressant dosage and duration adequacy.	ND	ND	12 678	Not effective
Bootsmiller [68]	2004	Educational strategie	Clinical guideline work group, task force, or committee clinical meetings discussing the guideline.	Assessment of clinical practice guideline implementation methods used in VAMC and comparison of strategies used in the VA with those methods found to be effective in the literature.	Providers	123 VAMCs	ND	Variably effective

Twenty-one original studies about the effectiveness of different interventions in changing clinical practice were identified. Most interventions studied had some effects (six interventions out of twenty-six, 23%, were not effective) especially when a well-designed intervention was used. The different types of strategies used were:

Six Combination of interventions [34, 47, 59, 68–70].

Five Use of reminders (e.g. on computer) [69, 71].

Four Educational strategies [68, 72, 73].

Three Mass media campaigns [74, 75].

Three continuous quality improvement and quality management [16, 43, 76].

Three Patient-mediated interventions [58, 60, 75].

One Substitution of tasks [77].

One Financial interventions [74].

The mostly effective change interventions and those more represented were combined interventions (always effective), reminders and computers use (mostly effective), educational strategies (mostly effective). The less effective were financial interventions (not effective) and mass media campaigns (mostly not effective).

Discussion

Despite evidence of their effectiveness, there is still a lack of adherence to guidelines across the world, regardless of pathology or level of care [78, 79]. In our review, most of studies reported adherence rates of less than 75%. These rates are largely influenced by the intrinsic characteristics of the studies and by factors related to patients, physicians and guidelines. They can be improved by carefully selected strategies.

Variability and lack of standard measurement on adherence

The evaluation of adherence is a heterogeneous process that lacks standardisation and the notion of adequate adherence is not defined.

Different guidelines exist for the treatment of depression, and adherence rates can differ based on the specific guidelines being followed. Guidelines from organisations like the American Psychiatric Association (APA) and the National Institute for Health and Care Excellence (NICE) might have varying recommendations, leading to differences in adherence rates. Guidelines are not intended to formally dictate medical practice; they support the physician’s decision-making and are open to individual interpretation [80]. For Dykes, “many guidelines lack explicit recommendations that can be implemented into objective measurement criteria” [81]. Most guidelines are complex and multifaceted. Faced with this complexity, researchers who have quantitatively studied guideline adherence are forced to simplify, either by choosing one or more of the most important (or easiest to measure) aspects of the guideline, or by attempting to create summary variables that integrate information from several aspects of the guideline and which are likely to reflect overall guideline implementation. They may also choose to evaluate sections where adoption may be lower than expected. On the other hand, the availability of clinical data to properly assess adherence may influence the choice of criteria studied. Approaches to measuring adherence are highly heterogeneous. In a minority of studies, adherence was measured using a composite score of different adherence criteria. In others, adherence was measured criterion by criterion or based on a single indicator of guideline adherence. The method used to define the rules for measuring adherence to the guidelines influences the observed adherence rate [82]. In the same study, rates can vary widely depending on the measurement criterion examined [83] or the definition used [6].

The data analysed came from a wide variety of sources, including administrative, pharmaceutical or medical records, patient interviews and provider surveys. The reason for choosing a particular type of data is not known. It may have been choosen in order to study a particular guideline component, or that the availability of a particular type of data dictated which guideline component should be studied. The data used have an impact on the adherence rates observed in a survey. For example, administrative pharmacy records on prescription do not reflect the medication actually taken by a patient. One study that utilised both claims information and a survey [75] found that the two methods produced different rates.

The samples used in studies vary. Some studies analysed the whole population [61, 84], while others select chart or patient samples or random samples from community populations [35, 41]. The diversity of these samples may have an impact on adherence rate results.

Adherence rates can vary between different healthcare settings, such as primary care clinics, psychiatric practices, and hospitals. For instance, primary care physicians have lower adherence levels than mental health specialists.

Given the wide variability in adherence rates, we have attempted to analyse the determinants of adherence.

Factors influencing adherence

Patients-related factors

Demographic or clinical factors have had a considerable variable effect on whether an individual would receive appropriate care [85].

Women received guideline-concordant therapy more often than men. It has been suggested that women are more likely to seek, accept and continue treatment because of their reduced perception of stigma and better ability to translate feelings of distress in a conscious recognition that they have emotional problems [86].

In patients 75 years of age and older, antidepressant treatments were more frequently determined to be compliant with standards. Due to their advanced age and likely worse general health, older patients may benefit from more regular medical home visits [87]. This better compliance among older patients might also be due to greater concern for their health and the fact that they follow the advice of healthcare professionals more closely [88].

Patients with a lower level of education seem to be disadvantaged with respect to the receipt of guideline-concordant care from their general practitioner in comparison with patients with a higher level of education [30]. This difference could be explained by a lack of knowledge of available services, a lack of insight into their mental problems or a less open attitude towards disclosing and discussing personal problems among the less well educated [89, 90]. In contrast, Piek et al. [28] found that a higher education level decreased the likelihood of maintenance treatment. It has been supposed that patients with a higher education level might favour psychotherapy over antidepressant treatment, or that GPs might think that patients with a lower education level are less able to benefit from psychotherapy [28, 91].

Minority groups were mostly less likely to receive guideline-adherent treatment for depression. The inadequate treatment received by minority groups could be due to their failure to recognise depression as an illness requiring medical care, misconceptions about antidepressants, not knowing where to go for care, lack of access to the health care system, or they had such access, but the care that they ultimately received was inadequate [31]. In the United States, the relatively lower rate of insurance coverage among ethnic minorities may restrict service use through differences in socioeconomic status or in knowledge about accessing health insurance. Indeed, residing in poor neighbourhoods or areas where there are more female-headed households has been associated with less adequate treatment among ethnic minorities, whereas white families may have been employed in higher paying jobs that offer private insurance [33]. Moreover, a strategy that improves the treatment of depression failed to affect its management when staff involvement with the project served an economically deprived and ethnically diverse population [34]. Conversely, a study conducted in the Netherlands did not support the general idea that patients from non-Western ethnic minorities are less likely to receive guideline-compliant care for depression. One possible explanation is that the Netherlands - like many other Western countries - has a long history of adapting (mental) health services to meet the needs of culturally diverse patients [35].

Residing in a large city and shorter travel time to access to care was found to be associated with increased odds of receiving adequate treatment. This could be explained by the higher levels of health service provision in cities and the siting of general hospitals there [30]. Moreover, patients with poorer geographical accessibility to services (longer travel times) have less frequent contact with their provider [37], which raises serious problems of continuity of care for patients in rural areas and would imply the existence of a serious problem of equity in the delivery of health services. Fuller et al. [92] hypothesised that as mental illness is stigmatised more in rural areas, the difficulty in recognising and accepting the diagnosis of depression may also play a role in the explanation.

In addition, a need perceived by patients for medication was most strongly associated with the delivery of guideline-concordant care and was perhaps more influential than clinical need factors [67].

Patients with more severe symptoms and greater disability were most often treated according to the guidelines, indicating that those with greater clinical need for care, actual or perceived, are more likely to receive it. This may be due to the fact that GPs must screen patients, based on which symptoms require more thorough treatment and which do not [93]. Furthermore, where patients with severe depression receive inadequate treatment, this may be a problem of failed treatment initiation rather than the selection of inadequate treatment [54].

In the same way, patients with comorbid physical illnesses were more likely to receive guideline-consistent care. Those requiring treatments for comorbid conditions may be more willing or have more opportunities to receive treatment for their mental disorders [94–97].

Comorbid anxiety disorders also appear to be associated with adequacy of treatment [6]. Young et al. [98] suggested that depressive symptoms are easier to detect in people presenting both conditions.

Conversely, psychotic or neurotic symptoms associated with depression, or symptoms that are not typical of depression, reduced the level of guideline adherence [99]. This could also be related to patient factors, such as disorganisation, cognitive deficits or communication barriers, rather than competing demands [100].

Patients with comorbid depression and substance use disorders receive lower quality care than those with depression but without such disorders. They often suffer from complex psychological presentations characterised by multiple symptoms, such as reduced motivation and disorganisation, added to the stigma associated with both depression and substance use disorders. All this can lead to lower treatment retention [32]. Such considerations may indicate the continued need to improve recognition and treatment of mental illness, especially among patients with mild or unusual symptoms and with comorbid substance use disorders [26, 40].

Physicians-related factors

The sector in which care is received is an important predictor of adequacy of treatment: adequate treatment for depression was received more frequently in secondary care than in primary care [6]. Primary care physicians face many barriers in delivering adequate mental health treatment [48]: lack of awareness of specific depression guidelines, insufficient training at medical school, attitudes and beliefs. Castro et al. demonstrated a greater sensitivity for the diagnosis of depression in secondary care than in primary care [19]. This increased likelihood of receiving adequate treatment is higher among patients with a valid diagnosis [19, 53]. Doctors who are more sensitive to the patient’s non-verbal behaviour are more likely to make a psychiatric diagnosis, while those who tend to see patients as responsible for their depression, exaggerating or prolonging it, have the opposite propensity and are less likely to detect psychiatric disorders [101].

The “mental health” clientele of GPs includes more people with little or no formal education, while that of “shrinks”, whoever they may be, includes more people with post-graduate qualifications [102, 103]. Unlike GPs, mental health specialists tend to see more severely depressed patients. Therefore, it can be surmised that patients with greater needs (in terms of severity) may be more motivated and compliant with the provider’s medication instructions [28, 44]. These factors come together to make it more difficult for GPs to detect disorders and prescribe appropriate treatments.

This difference in guideline adherence between the primary care and mental health sectors is also true for other specialist care sectors, in cases of comorbidity associated with depression [45, 104]. This may occur because primary care providers know that their patients are being managed in specialised sector, allowing them to focus on the patient’s depression.

Adherence to treatment guidelines can be positively impacted by involvement in peer-reviewed networks, interaction with colleagues, and exposure to expert opinion [5, 105].

Understanding these factors can help healthcare systems and policymakers to develop strategies to enhance physician adherence to depression treatment guidelines, ultimately improving patient outcomes.

Guidelines-related factors

Among factors affecting guideline compliance identified by Cabana et al., a lack of awareness, familiarity and agreement with guidelines were most commonly cited [48].

It is difficult for any physician to be aware of every applicable guideline and apply it critically to practice. GPs often disagreed with recommendations because they disputed the underlying evidence provided or felt that it was not clear why they should apply them [106].

Characteristics of the guidelines themselves affect their use. Guidelines that are easy to understand, can be easily tried out, and do not require specific resources, are more likely to be implemented [11].

The problem is that guidelines are mostly inconvenient or difficult to use. The trialability of a guideline and its complexity are significant predictors of adoption. Trialability is “the degree to which an innovation may be experimented with on a limited basis” [48].

The challenge is to produce simple and clear guideline recommendations that also address the complexity of problems seen in daily practice [106]. Guidelines should be written and published, but it is imperative that thought be given to how they will be implemented [107].

Effects of guideline adherence

Evidence-based care for depression decreases the personal and societal burdens of depression. Adherence to guidelines improves treatment outcomes [61]. Indeed, the results from the study of Datto et al. suggest that physician adherence predicts patient outcomes [58]. One of the benefits of guidelines is that they help clinical decision-making and provide informative resources for patients and their caregivers [18].

Some studies found that there was no positive treatment effect for patients with subthreshold depression or that improvement in clinical outcome occurred only in patients with major, but no minor, depression [37, 59]. This result suggests that patients meeting diagnostic criteria for major depression may respond better to medication management than patients with subthreshold depression. It may also simply reflect a floor effect: patients that meet the criteria for current major depression have greater room for improvement than those with subthreshold or minor depression.

For patients with both depression and diabetes, optimising drug therapy for depression may be important in helping diabetic patients with depression to achieve adequate glycaemic control [64] even if these elements seems to be qualified in view of the negative impact that certain antidepressant can have on glycaemic balance.

The work of Melfi et al. provides further evidence that adherence to current medication recommendations could substantially reduce the likelihood of relapse and recurrence of depression [61]. Preventing or delaying a relapse or recurrence of depressive disorders can have an economic impact by reducing the need for costly procedures [20], hospitalisation [27] and other forms of expensive care. More importantly, it can have a profound clinical impact and help maintain normal functioning.

Furthermore, patients who received appropriate care were found to have higher rates of employment than those who did not receive appropriate care [63, 108].

Clinician adherence improvement

Various approaches to implementing guidelines have been described, each with varying outcomes. “None of the approaches is superior for all changes in all situations; we probably need them,” state Grol et al. [14]. The dissemination of guidelines is an ineffective method. Pedersen et al. indicate that more complex interventions (i.e., those with provider education plus additional components and implementation strategies such as the tailoring of training to address personal barriers to implementation) may be associated with more favorable outcomes [109]. The use of multiple approaches to guideline implementation has been more effective than a single intervention [68, 69]. Indeed, two randomised clinical trials employing multiform interventions produced positive results [47, 59]. However, Scott et al. found that this model had no effect on depression management when staff involvement in the project was passive rather than active, when its practice was less well resourced, and when it served an economically disadvantaged and ethnically diverse population [34]. Optimism about the success of multifaceted interventions is also moderated by consideration of the complexity of the strategies employed. For instance, Katon et al. [59] provided patient education on depression and taught patient cognitive-behavioral techniques in addition to interventions to physicians. This type of intervention is certainly effective, but at huge additional cost, limiting the scope for effective implementation. Finally, guideline adherence depends on specific and active interventions. Lin et al. found that guideline adherence returned to pre-intervention levels six months after the intervention was discontinued [73].

It should also be noted that deviation from an algorithm does not always indicate that the clinician does not intend to adhere to the algorithm, but may reflect the clinician’s operation within the organisation. The resources available for care provision vary from clinic to clinic, as do the organisational structure and culture of the clinic. The role of the organisation in providing the resources, leadership, planning and infrastructure needed to change processes is critical to the implementation of any new service program [72]. In addition, ongoing monitoring of compliance and outcome measures through quality management programs is necessary [73].

Limitations

This review may be affected by publications bias, as studies with positives results are more likely to be published, and, because studies other than those written in English were not taken into account. Furthermore, the included studies vary in terms of methodology, interventions and outcome measures, which limits generalisation on the one hand, and on the other, makes it impossible to standardise the results of the analysis. In addition, the search was limited to studies published up to 2024, meaning that more recent research may not be have included, and, the search strategy was limited to open access databases (PubMed, Web of Sciences and Cochrane) which might have resulted in the omission of relevant studies found in other sources.

Conclusion

In conclusion, the absence of standard method for measuring for adherence and the variability in rates of adherence to depression treatment guidelines highlight the complexity in assessing and implementing guideline-concordant care and the associated challenges. Factors influencing adherence, such as those related to patients and their comorbid conditions, physicians or guideline-related factors play a significant role in determining the likelihood of receiving appropriate treatment for depression. Understanding these factors can help to improve physician adherence to guidelines, ultimately leading to better patient outcomes and the reduction of the societal burden of depression. A multifaceted approach to guideline implementation, with complex interventions including the active involvement of clinicians, ongoing monitoring, and organisational support is crucial for successful guideline adherence.

Authors’ contributions

All authors have made substantial contributions to conception and design (S.D., E.H., H.J.), acquisition of data (S.D., E.H., H.J.), and analysis and interpretation of data (S.D., E.H., H.J.). All were involved in drafting the manuscript (S.D., E.H., H.J.) and providing revisions (S.D., E.H., H.J.). All authors have given final approval of this final version to be published. All authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Funding

The review was not funded.

Data availability

All data generated or analysed during this study are included in this published article.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.