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PLOS One logoLink to PLOS One
. 2026 Feb 26;21(2):e0327933. doi: 10.1371/journal.pone.0327933

Attrition and associated factors among patients on chronic antihypertensive therapy at Mulago hospital, Uganda: A mixed method study

Nathan Ntenkaire 1,2,*, Mark Kaddu Mukasa 3, Patience Muwanguzi 1,4, Brian Mikka 1, Sandra Lunkuse 1,5, Julius Mubiru 1,#, Maxwell Okwero 1,2,#, Beatrice Basuuta 1, Douglas Bulafu 1,6,#, Joan N Kalyango 1,7
Editor: Ignatius Ivan8
PMCID: PMC12944796  PMID: 41746984

Abstract

Background

Attrition among patients on chronic antihypertensive therapy is a significant problem that can lead to serious health consequences, including uncontrolled blood pressure. Several factors underlie attrition, so healthcare providers must address them to prevent treatment discontinuation and ensure optimal outcomes. Therefore, this study assessed attrition and associated factors among hypertensive patients from January 2020 and December 2022.

Methods

A sequential explanatory mixed-methods design. The quantitative study was a retrospective cohort study design using files of 1215 hypertensive patients. The qualitative study employed an explanatory descriptive design among 16 patients. A data abstraction tool and an interview guide were used for data collection. Attrition was defined as patients who were lost to follow-up. Extended Cox regression was used to determine the factors associated with time to attrition at 5% level of significance and qualitative data analysis employed a thematic analysis codebook.

Results

The attrition proportion was 56.8% (95% confidence interval (CI) 54.0–59.7) with most patients getting lost to follow-up in 2020 (64.9%) and fewest in 2021 (54.7%). Age (hazard ratio (HR)=0.947, 95% CI 0.931–0.963), female Sex (HR = 0.734, 95% CI 0.620–0.869), residence outside Kampala (Capital City) (HR = 1.24, 95%CI 1.063–1.455), 2022 cohort entry year (HR = 1.433, 95% CI 1.156–1.777), last visit systolic blood pressure (SBP) (HR = 1.014, 95% CI 1.009–1.018), and last visit diastolic blood pressure (DBP) (HR = 0.947,95% CI 0.931–0.963) were associated with time to attrition. Loss to follow-up (LTFU) was driven by structural and contextual barriers, health system challenges, and illness perceptions and health-related limitations.

Conclusion

Hypertensive patient attrition proportion is high, below the Centers for Disease Control and Prevention’s 80% retention target. This calls for innovative retention strategies, and targeted support for high-risk groups like the male patients and those distant from the health facility. Patient-centered approaches addressing structural and health system barriers are essential to improving retention in hypertension care.

Introduction

Non-communicable diseases (NCDs) are responsible for the majority of deaths worldwide, low and middle-income countries (LMICs) contribute to approximately 75% of all NCD-related fatalities [1]. Globally, an estimated 1.28 billion adults (30–79 years old) have hypertension, and the majority (two-thirds) of these live in LMICs [2]. In sub-Saharan Africa (SSA), the prevalence of hypertension has risen, with estimates in 2019 reaching 48% (CI: 42–54%) among women and 34% (CI: 29–39%) among men [3]. In Uganda, hypertension is estimated to have a prevalence rate of 26.4% in general, with the highest rate of 28.5% occurring in the central region, and the lowest rate of 23.3% in the northern region. [4]. Furthermore, the prevalence rates of hypertension in urban and rural areas are estimated to be 28.9% and 25.8%, respectively [5]. Only 3.6% of hypertensive patients in Uganda have their blood pressure (BP) under control, and hypertension (HTN) and other NCDs account for 33% of all deaths with a 22% probability of dying prematurely from either cardiovascular disease, cancer, chronic respiratory diseases or diabetes [6]

Although HTN cannot be cured, it can be controlled with medication, dietary changes, or a combination of both [7]. Patients who consistently engage in medical care at a healthcare facility are considered to be retained in hypertension care. For the long-term management of hypertension and program maintenance, it is critical to have high retention rates. However, in resource-limited settings, 1-year retention rates are often below 50% [8]. Retention on antihypertensive therapy is essential for controlling hypertension and lowering the risk of complications related to high BP. Hypertension can lead to various complications, such as cardiovascular disease, kidney disease, cognitive impairment, and eye damage. These complications can cause a range of burdens, including higher healthcare expenses, reduced productivity and quality of life, and an increased risk of disability and premature death [9].

Attrition from antihypertensive therapy varies in different studies. Studies done in Cambodia and India reported attrition ranging from 9.2% to 61.5% [10,11]. The factors associated with attrition include patient-related factors such as sex, smoking, age, body mass index (BMI). illiteracy, low income, multi-person household [12,13]. There are also clinical factors such as uncontrolled BP, adverse events, medication regimen complex index, and history of hospitalization [14,15]. In addition, health system factors such as stock out, quality of health services, physician-patient relationship, health education and availability of medication have been associated with attrition [16]. With the rising prevalence of chronic diseases, health systems in Africa are struggling to maintain continuity of care [17], yet no research has been conducted in Uganda to determine the attrition proportion of patients with hypertension and it is hypothesized that attrition proportions are high and its predictors are varied. Additionally, patients view on the reason for LTFU from hypertension care is less known, Therefore, this study determined attrition and associated factors among hypertensive patients and explored reasons for LTFU from the perspective of patients identified as lost to follow-up.

Materials and methods

Study setting

The study was conducted at the hypertension clinic in the medical outpatient’s department of Mulago Hospital, which is situated in Kampala, Uganda’s capital city. The hospital serves as the primary teaching facility for the College of Health Sciences at Makerere University. It offers comprehensive healthcare services across numerous medical and surgical subspecialties, including dentistry, emergency medicine, pediatrics, and intensive care. The clinic is open on Mondays, except on public holidays, and is staffed by specialist physicians, including a cardiologist, nurses, and records officers as well as laboratory and pharmacy support. Approximately 438 patients are initiated on antihypertensive treatment (AHT) each year at this clinic.

Study design and population

A sequential explanatory mixed methods design, consisting of two distinct phases by Tashakkori and Creswell [18] was adopted. The quantitative study phase was a retrospective cohort, and the qualitative study phase was a descriptive explanatory design. For the quantitative study, files of hypertensive patients who were registered at the Mulago hypertension clinic between January 2020 and December 2022 were included. Patients’ files missing data on more than 30% of the studied variables were excluded. Patients who were registered between January 2020 and December 2022, who were confirmed as lost to follow up and consented to participate were included in the qualitative study. Patients who were transferred to other health facilities and those who did not understand English or Luganda were excluded from participation in the interviews.

Sample size and sampling procedure

The sample size was determined to address two objectives: (i) to determine the attrition proportion and (ii) to determine factors associated with time to attrition among hypertensive patients. For determining the attrition proportion, the Kish (1965) formula for determining sample size was initially applied [19]. Using an attrition proportion of 9.2% among hypertensive patients reported by Meena and colleagues in India, at a 95% confidence level and a 5% margin of error [20]. A minimum sample size of 397 of patients file was required

To determine the factors associated with time to attrition, the sample size was estimated using the formula for survival data (S1 Appendix). Assuming a two-sided 5% level of significance, 80% power, and proportions of patients retained in care of 67.9% of the 53 patients aged 41–52 years and 79.6% of the 54 patients aged 53–65 years as reported by Given et al. (1985) [21].

Therefore, the minimum number of patient files required was 1006 after accounting for 10% missing data. Much as the overall calculated minimum required sample size was 1,006, the study employed a consecutive sampling approach, in which all 1,215 patient files that met the eligibility criteria during the study period (January 2020–December 2022) were included in the analysis.

Purposive sampling with maximum variation was used to select participants for the qualitative study, considering factors such as age, sex, residence, presence of comorbidities, and adverse events, from the 690 patients identified as lost to follow-up. Interviewing of participants was stopped at the point where additional interviews no longer yielded new insights and adequate depth of understanding of the topic had been obtained.

Variables

The dependent variable was time to attrition. Attrition was defined as patients who were lost to follow-up and loss to follow up was referred to patients who missed ≥2 consecutive clinic appointments. Independent variables consisted of patient-related factors, clinical factors, and health system factors. Patient-related factors included age, sex, residence, occupation, alcohol use, smoking status, herbal medicine use, and marital status. Clinical factors comprised baseline systolic and diastolic blood pressure, presence of comorbidities, history of hospitalization, number of antihypertensive medications, reported side effects, cohort entry year, the antihypertensive regimen, and last-visit systolic and diastolic blood pressure. The health system factor assessed was the occurrence of medicine stock-outs.

Follow-up appointments varied by patient, with each given an individualized schedule based on clinical condition and treatment response. For survival analysis, the time origin was the date of registration at the clinic, and person-time was calculated from this date until attrition and those without attrition were censored at the date on which data was collected.

Data collection

Secondary data obtained in the hospital for patient’s clinical monitoring and evaluation was used in this study and it was accessed between 07th July 2023–20th November 2023.

The primary source of data was the patient files kept at the hypertension clinic and the pharmacy register to complement the information. The data abstraction tool was pretested on 10 patient files and standardized before being used for actual data collection and these 10 patient files were not part of the final patient files considered. Demographic, clinical and health system data was collected by two trained registered clinic nurses. The Principal Investigator (PI) regularly double-checked the filled data abstraction tool by trained registered record officers against the patient files to ensure that the data collected was accurate and free of errors.

For the qualitative component of the study, to enhance reflexivity phone interviews were conducted by two trained records officers who were familiar with the hypertension clinic environment but were not directly involved in clinical decision-making for the participants. This minimized undue influence while allowing rapport to be established. The Principal Investigator (PI), a clinical epidemiology scholar with training in qualitative research, supervised data collection and provided oversight to minimize interviewer bias. The two trained records officers contacted confirmed lost to follow up patient’s and guided them through the informed consent process. The participants were recruited from 20th January 2024–28th January 2024. Those who provided consent were interviewed by phone to explore the reasons for their LTFU. The interviews were conducted using an interview guide developed in both English and Luganda, based on participant language preference (S2 Appendix). Interviews were audio recorded with prior permission from the participants and were held in the records office, in the presence of the Principal Investigator (PI). Each interview lasted a maximum of 30 minutes. To minimize loss of information, field notes were also taken in notebooks during each session. Interviews continued until thematic saturation was reached, defined as the point when no new codes or insights emerged, which occurred after 16 interviews. To ensure the credibility and dependability of the findings, patient verification and peer-review quality control practices were employed. Transcripts were not returned to participants for feedback due to nature of interviewed participants.

Data management

The collected quantitative data was entered into EpiData Manager version 4.7.0, where it was verified for accuracy, consistency, and completeness. Variable-level missingness was minimal (<1%); missing values (DBP at last visit) were imputed using the respective measure of central tendency, and missing age values were computed from dates of birth of the patients. It was then cleaned and edited before being analyzed using Stata version 15.0. For qualitative data, audio recordings in English and Luganda were transcribed verbatim and translated into English text before analysis. Both qualitative and quantitative data were securely stored on a password-protected computer to ensure data confidentiality.

Data analysis

Descriptive analysis where measures of central tendency and dispersion (mean, standard deviation, median and interquartile ranges (IQR)) were computed for numerical variables. For categorical variables, frequencies and percentages were computed, and tables and graphs were used to visualize the analyzed data.

A proportion was obtained to determine the percentage of patients that experienced attrition by dividing the number of hypertensive patients who were lost to follow-up by the study sample size.

The probabilities of patients staying in care at different intervals of the follow-up period were determined using the Kaplan-Meier method, and the log-rank test was used to determine the significance of observed differences between groups. The proportional hazards assumption was evaluated using both graphical methods and the Schoenfeld residuals test which was statistically significant (p = 0.0096) (S3 Appendix), indicating that the proportional hazards assumption was violated for the model overall. In particular, the test revealed that last-visit DBP also violated the assumption (p = 0.0015) hence the model extended to include time varying covariates. Both baseline and last-visit SBP and DBP measurements were included in the model. Baseline SBP and DBP and last-visit SBP, which met the proportional hazards assumption, were modeled as fixed covariates representing patients’ initial and most recent clinical status.

Variables with p-values of ≤ 0.2 at bivariate analysis and those known to be associated with attrition from literature were considered for multivariate analysis. A chunk test was used to compare the reduced and full model and therefore assess for interaction (S4 Appendix). Confounding was then assessed where a variable was considered a confounder if the change in the hazard ratio (HR) was > 10%. Hazard ratios (HR), p-values and the 95% confidence intervals were reported.

Qualitative data analysis involved the utilization of a thematic analysis codebook, applying the 6 phases inherent in the thematic analysis (TA) approach [22].The data was transcribed, translated in English, coded, and synthesized using Open Code version 4.02 to yield notable themes [23]. Three trained data coders independently coded the transcripts to enhance reliability and reduce individual coder bias. A thematic analysis codebook was applied, and themes were inductively derived from the data. Discrepancies in coding were resolved through discussion and consensus among the coders. Analytical rigor was ensured through peer debriefing with the research team and systematic documentation of coding decisions. Data saturation was reached after the 16th interview when no new codes or insights emerged, and an illustrative table (S1 Table) presents each theme with representative participant quotations. Participants did not provide feedback on the findings.

Ethical considerations

Permission to conduct the study was granted by the Clinical Epidemiology Unit (CEU). Ethical approval was obtained from the Institutional Review Board (IRB) through the School of Medicine Research and Ethics Committee (SOMREC) of Makerere University College of Health Sciences (Mak-SOMREC-2023–584). Additionally, for retrospective records review, SOMREC approved a waiver of consent to allow the use of patient records. Written informed consent was obtained from participants confirmed to be lost to follow-up, who took part in the qualitative phase of the study. Trained registered record officers, together with the principal investigator, reviewed patient files, ensuring that any information extracted was kept strictly confidential and not disclosed to third parties. Anonymity was maintained by omitting identifying variables such as names during data extraction. Participants were provided with detailed information about the study in English or Luganda, and confidentiality was further ensured through anonymized transcripts and secure, password-protected data storage accessible only to the research team.

Results

Among the 1,278 patients registered at clinic, 63 were excluded due to missing more than 30% of study data. A total of 1215 patient files meeting the eligibility criteria were selected for the quantitative study. Of these, 20 participants were selected to take part in the in-depth phone interviews (Fig 1).

Fig 1. Study profile.

Fig 1

Characteristics of patients registered at the clinic from January 2020 to December 2022

More than half of the patients resided outside Kampala (58.8%, n = 714) and majority were female (76.1%, n = 924), with mean age of 56.5 years (SD 13.9). The majority did not smoke (99.4%, n = 1208), while 98.2% had no history of alcohol use (98.2%, n = 1193). About half had a comorbidity (50.8%, n = 617), while 92.8% (n = 1128) had never been hospitalized and 58.5%(n = 711) had experienced side effects. The median baseline SBP (1st, 3rd quartile) was 150 mmHg (138, 168) and the median baseline DBP was 87 mmHg (77, 97).

Regarding the drug regimen, the majority were on combination therapy (86.3%, n = 1048) and the least on diuretics (0.08%, n = 10). Most of the patients (59.6%, n = 724) had prescriptions of ≤ 2 antihypertensive drugs. Medicine stock outs were reported in 80.3% (n = 922) of the patients during at least one of the visits.

A small part of the patients used herbal medicine (1.0%, n = 12). On the last clinic visit, the median SBP was 145 (132, 159), and the median DBP was 83 (75, 92). Business was the most common occupation among the patients (29.1%, n = 188) followed by peasants (24.6%, n = 159) (Table 1).

Table 1. Characteristics of patients registered at the clinic from Jan 2020-Dec-2022 (n = 1215).

Variable Category Number (N) Percentage (%)
Residence Kampala 501 41.2
Outside Kampala 714 58.8
Cohort entry year 2020 231 19.0
2021 502 41.3
2022 482 39.7
Sex Male 291 24.0
Female 924 76.0
Mean age (SD) 56.5 (13.9)
Smoking status Yes 7 0.6
No 1208 99.4
Alcohol use status Yes 22 1.8
No 1193 98.2
Comorbidity Yes 617 50.8
No 598 49.2
Hospitalization Yes 87 7.2
No 1128 92.8
Side effects Yes 711 58.5
No 504 41.5
Baseline SBP
Median (1st, 3rd quartile) 150 (138,168)
Baseline DBP
Median (1st, 3rd quartile) 87 (77,97)
Drug regimen Combination 1048 86.3
CCB 72 05.9
ACE-I or ARBs 52 04.3
Beta blocker 33 02.7
Diuretics 10 00.8
Number of antihypertensives ≤2 724 59.6
>2 491 40.4
Medicine stock-out Yes 922 80.3
No 226 19.7
Herbal medicine use Yes 12 01.0
No 1203 99.0
Last visit SBP
Median (1st, 3rd quartile) 145 (132,159)
Last visit DBP
Median(1st, 3rd quartile) 83 (75,92)
Marital status Single 7 00.6
Married 448 36.9
Other 760 62.5
Occupation(n = 647) Business 188 29.0
Peasant 159 24.6
House wife 122 18.9
Health worker 59 09.1
Teacher 26 04.0
Engineer 18 02.8
Driver 13 02.0
Security 11 01.7
Other 51 07.9

CCB-Calcium Channel Blockers, ACE-I-Angiotensin-Converting Enzyme Inhibitor, ARBs- Angiotensin II Receptor Blockers and Other (Waitress, Evangelist, Designer, Journalist, shopkeeper, Office assistant, banker, Surveyor and carpenter).

Attrition among patients registered at the clinic from Jan 2020 and Dec 2022

Of the 1,215 patients, 690 experienced attritions, resulting in an overall attrition proportion of 56.8% (95% CI: 54.0–59.6). The median duration of follow-up was approximately 16 months. Patients registered in 2020 had the highest attrition (64.9%), followed by 2022 (55.0%), and 2021 had a relatively reduced attrition (54.7%) When considering sex, male patients had a greater attrition (64.6%) than females (54.3%). Furthermore, patients residing outside Kampala had a relatively higher attrition (59.8%,) than those dwelling within Kampala, where the attrition was 52.6%. Kaplan-Meier survival analysis revealed statistically significant differences in survival probabilities based on sex (p < 0.0001), place of residence (p = 0.0001), and cohort entry year (p < 0.0001) (Fig 2).

Fig 2. Kaplan Meier survival curves for attrition among patients between Jan 2020 and Dec 2022 (A-Cohort entry year, B-Sex, C-Residence).

Fig 2

Factors associated with time to attrition among patients between January 2020 and December 2022

In bivariate analysis factors such as residence, cohort entry year, sex, smoking, age, side effects, baseline SBP, drug regimen, SBP on the last visit, and DBP on the last visit were selected for multivariate analysis (Tables 2 and 3). In multivariate analysis factors associated with attrition were age (HR = 0.904, 95% CI 0.877–0.932), residence: Outside Kampala (HR = 1.311,95%CI 1.121–1.533), Sex: Female (HR = 0.713, 95% CI 0.602–0.845), 2022 cohort entry year (HR = 1.433, 95% CI 1.156–1.777), SBP on last visit (HR = 1.013,95% CI 1.008–1.017) and DBP on last visit (HR = 0.957,95% CI 0.925–0.990). DBP on the last visit was a time-varying covariate with p = 0.006 (Table 4).

Table 2. Bivariate analysis for patient related factors associated with time to attrition among 1215 patients between Jan 2020-Dec 2022.

Variable HR (95% CI) p-value
Residence
 Kampala Ref
 Outside Kampala 1.374 (1.176-1.606) <0.001
Sex
 Male Ref
 Female 0.706 (0.597-0.835 <0.001
Age (per 1 year) 0.999 (0.993-1.004) 0.637
Smoking status
 Yes Ref
 No 0.682 (0.305-1.523) 0.351
Alcohol use
 Yes Ref
 No 0.896 (0.528-1.521) 0.685
Occupation
 Business Ref
 Peasant 0.650 (0.551-1.042) 0.245
 House wife 0.980 (0.678-3.050) 0.201
 Health worker 0.450 (0.310- 2.890) 0.254
 Teacher 0.720 (0.525-1.150) 0.325
 Engineer 0.691 (0.615-1.810) 0.980
 Driver 1.011 (0.434-1.431) 0.421
 Security 1.510 (0.781-3.100) 0.267
 Other 0.890 (0.343-2.194) 0.723

HR= hazard ratio, CI=confidence interval.

Table 3. Bivariate analysis for clinical and health facility related factors associated with time to attrition among 1215 patients between Jan 2020-Dec 2022.

tvc
Variable HR (95% CI) p-value HR (95% CI) p-value
Cohort entry year
2020 Ref
2021 0.925 (0.754-1.135) 0.455
2022 1.500 (1.213-1.855) < 0.001
Comorbidity
 Yes Ref
 No 1.149 (0.989-1.334) 1.149
Hospitalization
 Yes Ref
 No 0.798 (0.533-1.193) 0.271
Side effects
 Yes Ref
 No 1.134 (0.974-1.320) 0.107
Baseline SBP(per 1 mmHg) 1.002 (0.999-1.005) 0.178
Baseline DBP(per 1 mmHg) 1.000 (0.995-1.005) 0.934
Drug regimen
 CCB Ref
 Combination 0.769 (0.568-1.042) 0.090
 ACE-1 or ARBs 0.692 (0.427-1.122) 0.135
 Beta blockers 1.381 (0.852-2.239) 0.190
 Diuretics 0.825 (0.352-1.934) 0.658
Number of antihypertensives
  ≤ 2 Ref
 >2 0.925 (0.794-1.077) 0.315
Medicine stock out
 Yes Ref
 No 0.878 (0.714-1.080) 0.217
Herbal use
 Yes Ref
 No 1.646 (0.683-3.969) 0.267
Last visit SBP(per 1 mmHg) 1.009 (1.006-1.013) <0.001
Last visit DBP(per 1 mmHg) 1.015 (1.006-1.023) 0.001 0.998 (0.998 −0.999) <0.001

HR= hazard ratio, CI=confidence interval, tvc= time varying covariates.

Table 4. Multivariate analysis for predictors of time to attrition among 1215 patients between Jan 2020-Dec 2022.

tvc
Variable HR (95% CI) p-value HR (95% CI) P-value
Residence
 Kampala Ref
 Outside Kampala 1.244 (1.063- 1.455) 0.006
Sex
 Male Ref
 Female 0.734 (0.620- 0.869) <0.001
SBP on last visit (per 1 mmHg) 1.014 (1.009-1.018) <0.001
DBP on last visit (per 1 mmHg) 0.957 (0.925-0.990) 0.011 0.9989(0.9981-0.9997) 0.006
Age (per 1 year) 0.947(0.931-0.963) <0.001
Cohort entry year
2020 Ref
2021 0.937 (0.763-1.151) 0.537
2022 1.433 (1.156-1.777) 0.001

HR = hazard ratio, CI = confidence interval, tvc = time varying covariates. Continuous covariates are expressed per 1-unit increase, age (per 1 year) and SBP/DBP, per 1 mmHg).

Description of the participants that participated in the phone interviews

There were 20 patients out of the 690 found to be lost to follow up that were selected for the interviews, however only 16 interviewed. The mean age of the participants was 50 years (SD 11.99). 9 (56.3%) of the participants were female and 11 (68.8%) of the participants were residing outside Kampala. 5 (31.5%) of the participants had a comorbidity, 11 (68.8%) of the participants had experienced drug related side effects and 2 (12.5%) of participants reported to have been hospitalized in the past (Table 5).

Table 5. Description of the 16 participants that took part in the phone interview.

Characteristics Category n (%)
Sex Male 7 (43.8)
Female 9 (56.2)
Age
Mean (SD) 50 (12.0)
Residence Kampala 5 (31.3)
Outside Kampala 11 (68.7)
Presence of comorbidity Yes 5 (31.3)
No 11 (68.7)
Presence of side effects Yes 11 (68.7)
No 5 (31.3)
Hospitalization Yes 2 (12.5)
No 14 (87.5)

n-number of participants, %- percentage.

Underlying reasons for loss to follow up among patients lost to follow up

Participants reported a variety of factors contributing to LTFU from hypertension care. These were grouped into three major themes: [1] Structural and Contextual Barriers, [2] Health System Barriers, and [3] Illness Perceptions and Health-Related Limitations. Each major theme encompassed several subthemes (Fig 3), with each subtheme supported by illustrative participant quotations presented (S1 Table).

Fig 3. Coding tree.

Fig 3

Theme 1: Structural and contextual barriers

Preference for alternative source of medication.

Participants obtained medication from nearby private clinics and pharmacies, with some preferring herbal remedies as alternatives to conventional medicine ‘’I’m also a health work, most of the time I get my drugs from somewhere else, I buy from a pharmacy nearby home…….” (Female, LTFU), “…….my sibling at Najjanakumbi gave me some herbal medicine, that I use………” (Female, LTFU).

Financial hardship.

Economic hardship was a key deterrent to continued care as participants could not afford transportation to the clinic “……. I’ve been having a challenge of lack of money; I’ll harvest some maize to see if I can generate funds to come …….” (Male, LTFU).

Transportation barriers exacerbated by COVID-19 restrictions and geographical distance.

Participants reported that pandemic-related restrictions and long travel distances to the clinic affected their ability to attend appointments.

“……the problem is COVID-19 came in and destabilized movement, even public means we use was stopped…….” (Female, LTFU), “……. I met some people and they told me to go to Kasese hospital for treatment because the distance to Mulago was far……...” (Male, LTFU).

Social disruptions and emotional strain.

Participants reported bereavement, prolonged travel for burial ceremonies, and lack of support or caretakers as key reasons for missing hypertension clinic follow-up visits. “……I had some problems; I lost my relative and I traveled for burial and took long to come back…...” (Female, LTFU), “……I don’t have a caretaker, it is me who takes care of myself, my children who would take care of me are not around…….” (Female, LTFU).

Limited mobility due to advanced age.

Elderly participants reported mobility limitations as a reason for their loss to follow up. “……. being an elderly person and weak, I was tired and decided to just sit home and leave alone with going to the clinic……” (Female, LTFU).

Competing work demands and fixed clinic schedules.

Work-related obligations conflicted with non-flexible clinic schedules, led to LTFU

“… work is too much at the specialized hospital where I work, a few times I visited clinic people at work complained thinking I had gone to work somewhere else…” (Female, LTFU).

Theme 2: Health system barriers

Overcrowding and long waiting times.

Overcrowding and waiting for long before served at the clinic discouraged participants from returning for follow-up visits. “……. sometimes you reach at the clinic and you are made to stay in the queue for so long…….” (Female, LTFU), “…...I came to the clinic, there were very many patients and we would spend a lot of time there…….” (Female, LTFU).

Perceived medical rudeness and unfriendly provider attitudes.

Negative interactions with healthcare providers led to dissatisfaction and disengagement.

“…….. most of the doctors are rude, you ask them a question and he is rude and doctors are not willing to help….” (Female, LTFU).

Recurrent stockouts of prescribed medication.

Inconsistent availability of medication at the clinic pharmacy discouraged patients from returning. “……even when you get transport money, you don’t find medicine….” (Female, LTFU)

Frustration with appointment scheduling and inaccessible care.

Appointment frustration was a major reason participant missed follow-ups, as scheduling and securing timely visits were challenging. “……I was told to go see some doctor but I couldn’t find him for three weeks I came……” (Male, LTFU).

Theme 3: Illness perceptions and health-related limitations

Physical limitations due to hypertension-related complications.

Physical impairments resulting from complications of hypertension also impeded attendance of clinic visits.

“…...I stopped coming because I had a stroke and so it was hard for me to move….” (Male, LTFU).

Perceived lack of treatment effectiveness.

Some participants lost confidence in their treatment regimen, expressing doubts about its effectiveness. “……. I would not get any change after getting the medication……” (Female, LTFU)

Perceived wellness and the absence of symptoms.

Several participants discontinued follow-up because they felt physically well and did not perceive a need for ongoing care. “…. if I’m feeling well, is there need to come back to the clinic….” (Female, LTFU).

Integration of quantitative and qualitative findings

Quantitative analysis identified younger age, male sex, residence outside Kampala, entry in the 2022 cohort, higher systolic blood pressure at the last visit, and lower diastolic blood pressure at the last visit as predictors of attrition. Qualitative findings provided context to these associations. Patients living outside Kampala reported long travel distances, high transport costs, and competing livelihood demands, which contributed to disengagement. Male patients described prioritizing work obligations over clinic attendance, reflecting gendered health-seeking behaviors. Elevated systolic blood pressure was linked to attrition, and interviews revealed that perceptions of poor disease control or side effects led to frustration and withdrawal from care. In contrast, lower diastolic blood pressure was protective, consistent with accounts that feeling clinically stable encouraged continued follow-up. The higher attrition observed in the 2022 cohort coincided with health system challenges, including frequent medicine stock-outs and COVID-19 restrictions, which patients described as discouraging.

Overall, attrition was shaped not only by clinical status but also by structural, health system, and psychosocial factors. The joint display demonstrates how statistical predictors align with patient narratives, underscoring the need for retention strategies that address both measurable risks and the lived realities of patients (S2 Table).

Discussion

The study found an attrition proportion of 56.8% indicating that slightly more than half of the patients on chronic antihypertensive were lost to follow-up during the study period. This suggests that the retention is quite low to achieve the WHO targeted treatment goal of bp < 140/90 mmHg in all patients with hypertension [24]. These results were consistent with those reported previous studies. Engelland and colleagues among 4403 hypertensive patients, reported attrition proportion of 51% [25]. Similarly, Ramsay and colleagues observed a 50% attrition proportion among 40 hypertension patients attending a hypertension clinic over 15 months [26]. MA and colleagues reported > 30% attrition in a study of 520 hypertensive patients in China [11]. These comparable findings highlight the widespread challenge of retaining hypertensive patients in long term care.

However, these results were different from the studies by Meena and colleagues conducted among a group of 1036 hypertensive patients who were registered at the NCD clinic in Pratap Nagar, Jodhpur, India and Kassavou and colleagues conducted among 101 hypertensive people in a primary health care which reported a lower attrition proportion of 9.2% and 7.92% respectively among people with hypertension [27,28]. The difference in the attrition proportions could be due to the disparity in the study designs, sample size and study setting.

Attrition among patients was highest in the cohort entry year 2020, which coincides with the onset of the COVID-19 pandemic in Uganda. The country reported its first confirmed case in March 2020, and soon after, strict public health measures were implemented, including nationwide lockdowns, travel restrictions, curfews, and limitations on public transportation [29]. These measures, while necessary to curb viral transmission, significantly hindered patients’ ability to access routine healthcare services.

The patient’s place of residence was statistically associated with time to attrition among hypertensive patients. Patients who resided outside Kampala had 24.4% higher risk over time of loss to follow up compared to those who resided in Kampala. This might be due to the fact that individuals residing in Kampala had easy access to the clinic, being in close proximity to it. This explanation aligns with the qualitative findings, where living far away was identified as one of the key reasons for patients being lost to follow-up while undergoing chronic antihypertensive treatment. Similarly, A. Baldé and colleagues concurred in their findings, indicating that residing more than 5 km away from a healthcare facility was linked to an increased risk of LTFU among individuals living with HIV in Mali, a comparable chronic condition [30].

Patient sex was statistically associated with time to attrition among hypertensive patients. Female patients had a 26.6% lower risk over time of loss to follow up than their male counterpart. These findings are consistent with studies by Degoulet and colleagues conducted among 1346 medical records of hypertensive patients in Paris, and Hernandez and colleagues conducted among 6677 patients with hypertension or diabetes in Cambodia. [31,10] This could be because women are more likely to seek medical attention than the men [32]. However a study by Given and colleagues [33] found Sex not to be a significant predictor of attrition. This might stem from the fact that Given and colleagues [33] conducted a randomized controlled trial with a small sample size (153) compared to this study.

Age was significantly associated with time to attrition among patients with hypertension. For every 1-year increase in age of the patient, there was 5.3% decrease in time to attrition. Elderly patients tend to be concerned about their health compared to young individuals who exhibit less interest. This finding is in agreement with what was reported by Hernandez and colleagues in a study conducted in Cambodia among antihypertensive patients [13]. However, this finding diverges from our qualitative aspect which found advanced age as a reason for LTFU. The disparity could be due to the fact that most of the participants in the qualitative study were adults and most elderly.

Blood pressure measurements on the last visit date to the clinic were significantly associated with time to attrition. For every 1 mmHg increase in SBP at the last visit to the clinic, there was 1.4% increase in time to attrition. Additionally, for every 1 mmHg increase in DBP at the last visit to the clinic, there was 4.3% decrease in time to attrition and at any given time as it increases, the time to attrition decreases by 0.11%. Higher systolic blood pressure may prompt closer clinical monitoring or greater perceived risk, which could delay attrition, whereas elevated diastolic blood pressure may be perceived as less severe, leading to earlier disengagement. DBP levels change over time due to lifestyle modification, inconsistent adherence to medication and treatment adjustments by health care providers. While last-visit SBP and DBP were included in the model, residual bias may persist because last-visit measurements could have been recorded close to the attrition event

The calendar year a patient was registered at the clinic was significantly associated with time to attrition. Patients who were registered in the year 2022 had a 43.3% higher risk over time of attrition compared to those that were registered in 2020, possibly reflecting post-COVID health system adjustments. By 2022, although COVID-19 cases had subsided, changes in clinic operations and staffing, or follow-up procedures may have created new barriers to retention, increasing the likelihood of LTFU among this cohort.

Drug regimen was not associated with time to attrition in this study. While no previous studies have directly examined this relationship among hypertensive patients, evidence from chronic care settings suggest that medication regimens can influence retention. For example drug regimens have been associated with attrition among 58,115 people living with HIV (PLHIV) in China by Zhu and colleagues [34]. Although both hypertension and HIV require long term medication adherence, the populations differ in terms of treatment complexity, perceived severity, stigma and intensity of follow up. These contextual differences may explain why drug regimen influenced attrition in the HIV study but not in our hypertensive population.

Medicine stock out was not associated with time to attrition. However, a study conducted by Pasquet and colleagues in Abidjan, Côte d’Ivoire among HIV infected patients, a similar chronic illness found drug stock to be associated with interruption from care [35]. The findings from the qualitative aspect are in agreement with these findings as medicine stock-out was highlighted by participants as one of the reasons for LTFU.Several other factors including number of antihypertensive drugs, history of hospitalization, drug related side effects and smoking status were not associated with time to attrition. The absence of hypertension specific comparative studies limits direct contextualization of these findings. While some studies in other chronic disease populations have reported associations between similar factors, differences in disease burden, care models, medication complexity, and follow up schedules restrict their comparability [13,10,36,37].These findings therefore contribute new evidence indicating that these commonly hypothesized factors may play a limited role in attrition within hypertensive care setting.

The qualitative findings reveal a multidimensional interplay of why patients get lost to follow-up, categorized into structural and contextual barriers, health system barriers, and illness perceptions and health-related limitations. Structural and contextual issues such as financial hardship, transportation challenges especially heightened by COVID-19 restrictions and competing work demands illustrate the broader socioeconomic constraints that hinder continuity of care, consistent with findings from prior studies in developed and low-resource settings [3840]. Health system barriers, including long waiting times, perceived provider rudeness, and frequent medication stockouts, reflect systemic inefficiencies that erode patient trust and motivation, these findings are similar to what is reported in South Africa and in a narrative review conducted by systematically searching electronic databases [41,42]. Additionally, patients’ perceptions of being well and symptom-free, coupled with physical limitations, diminish their perceived necessity for ongoing care, consistent with findings from studies in the UK, USA, and Spain on low risk perception in asymptomatic hypertension [4345].

Study strength and limitation

The mixed-methods design provided comprehensive insights by integrating quantitative and qualitative findings. The qualitative component complemented and clarified the quantitative results, enriching the understanding of patient attrition and its associated factors.

However, this study had several limitations. Missing data from retrospective patient files, including variables such as education level, may have introduced unmeasured confounding. Consecutive sampling in the quantitative phase could have led to selection bias, limiting generalizability. Recall bias was possible in the qualitative phase, as participants might have forgotten or misreported past experiences. Moreover, the observational design restricts causal inference; thus, the identified relationships should be interpreted as associations rather than causal effects.

Conclusions

This study found a substantial attrition of 56.8%, with the highest number of patients lost to follow-up occurring in 2020, coinciding with the peak of the COVID-19 pandemic. Various factors were associated with time to attrition, including age, male sex, residing outside the capital city, and last visit BP measurements and cohort entry year. Furthermore, LTFU was driven by structural and contextual barriers, health system challenges, and illness perceptions and health-related limitations. These included financial hardship, long distances, COVID 19 restrictions, overcrowding, provider attitudes, and perceived lack of treatment benefit.

These findings imply that retention rates are below the Centers for Disease Control and Prevention’s 80% retention target [46], highlighting the need to implement targeted strategies to enhance patient retention, particularly among high risk groups. Strengthening tracking systems, improving access to healthcare, and minimizing the effects of external disruptions such as pandemics may support sustained patient engagement.

Supporting information

S1 Appendix. Detailed methodological sample size formulas for survival analysis.

(PDF)

pone.0327933.s001.pdf (114.8KB, pdf)
S2 Appendix. Interview guide.

(PDF)

pone.0327933.s002.pdf (46.4KB, pdf)
S3 Appendix. Graphical and statistical approaches used to assess for Cox PH assumptions.

(PDF)

pone.0327933.s003.pdf (421.5KB, pdf)
S4 Appendix. Assessing for interaction.

(PDF)

pone.0327933.s004.pdf (183.2KB, pdf)
S1 Table. Illustrative quotes linking each theme to representative participant responses.

(PDF)

pone.0327933.s005.pdf (205.8KB, pdf)
S2 Table. Joint Display Linking Quantitative Predictors to Qualitative Themes.

(PDF)

pone.0327933.s006.pdf (201.8KB, pdf)

Acknowledgments

We extend our sincere appreciation to the hypertension clinic staff for their invaluable support throughout this study, and to all the participants for their willingness to take part.

Data Availability

All data and materials underlying the findings of this study are available in a public repository. The anonymized dataset, stata dofile, and data dictionary have been deposited in Zenodo and can be accessed at https://doi.org/10.5281/zenodo.17553717.

Funding Statement

The author(s) received no specific funding for this work.

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Additional Editor Comments:

1. Methodological Clarity and Sampling Strategy

Issue: The sampling procedure and sample size calculation contain redundant explanations and inconsistent formulas (pages 5–7). The justification for using both Kish (1965) and survival data formulas is not clearly connected to study objectives.

Revision Suggestion: Clarify how the final sample size (n=1215) was derived and why it exceeds the calculated requirement. Streamline the sample size section by presenting a single, coherent formula with assumptions, parameters, and effect size justification.

2. Mixed-Methods Integration and Design Justification

Issue: Although the study uses a sequential explanatory mixed-methods design, the integration of quantitative and qualitative findings is not explicitly described in the Results or Discussion sections.

Revision Suggestion: Add a section explicitly describing how qualitative results complemented quantitative findings (e.g., a joint display or integrated interpretation paragraph). State how qualitative insights influenced the interpretation of statistical results.

3. Statistical Rigor and Model Selection

Issue: The rationale for using an Extended Cox Regression Model is mentioned (violation of proportional hazard assumption) but not shown graphically or statistically. Furthermore, the proportional hazards test results are not reported.

Revision Suggestion: Include diagnostic plots or a supplementary figure/table demonstrating the proportional hazard assumption violation. Provide the name of the variable that violated the assumption and justify the model extension quantitatively.

4. Validity and Reliability of Qualitative Analysis

Issue: The qualitative phase describes thematic analysis with independent coders, but there is no mention of intercoder reliability or saturation confirmation process beyond “data saturation was achieved after 16 interviews.”

Revision Suggestion: Specify whether intercoder agreement was measured (e.g., Cohen’s kappa) and describe the analytical validation process (peer debriefing, triangulation, or audit trail). Add an illustrative quote table linking each theme to representative participant responses.

5. Overinterpretation of Quantitative Findings

Issue: The conclusion implies that factors such as age and male sex cause attrition, which overstates the observational design. Phrases like “patients who resided outside Kampala were 31% more likely to get lost to follow-up” may imply causality rather than association.

Revision Suggestion: Revise language to emphasize associations and avoid causal implications. For example, use “was associated with” instead of “led to” or “caused.” Include a clear statement acknowledging the limitations of observational inference.

6. Contextualization with Existing Literature

Issue: The discussion references multiple unrelated chronic disease studies (e.g., HIV, diabetes) without sufficient justification for their analogy to hypertension care. Regional literature from sub-Saharan Africa on hypertension retention is underrepresented.

Revision Suggestion: Strengthen discussion by citing and comparing results with regionally relevant hypertension adherence studies (e.g., Nigeria, Kenya, Tanzania). Discuss context-specific barriers such as drug stockouts or urban–rural disparities using LMIC evidence.

7. Writing Structure and Presentation

Issue: The manuscript is lengthy and contains redundant phrases (e.g., repeated mention of “Mulago hospital” and “chronic antihypertensive therapy”). Tables are numerous but lack clarity on the meaning of abbreviations, and figure legends (e.g., Fig 2) are insufficiently described.

Revision Suggestion: Streamline narrative flow by merging repetitive sentences and ensuring all abbreviations are defined upon first use. Improve figure/table captions for stand-alone comprehension. Move extensive methodological formulas and supplementary data into appendices.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Partly

Reviewer #3: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: I Don't Know

**********

3. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

Reviewer #1: This is an automated report for PONE-D-25-33575. This report was solicited by the PLOS One editorial team and provided by ScreenIT.

ScreenIT is an independent group of scientists developing automated tools that analyze academic papers. A set of automated tools screened your submitted manuscript and provided the report below. Each tool was created by your academic colleagues with the goal of helping authors. The tools look for factors that are important for transparency, rigor and reproducibility, and we hope that the report might help you to improve reporting in your manuscript. Within the report you will find links to more information about the items that the tools check. These links include helpful papers, websites, or videos that explain why the item is important. While our screening tools aim to improve and maintain quality standards they may, on occasion, miss nuances specific to your study type or flag something incorrectly. Each tool has limitations that are described on the ScreenIT website. The tools screen the main file for the paper; they are not able to screen supplements stored in separate files. Please note that the Academic Editor had access to these comments while making a decision on your manuscript. The Academic Editor may ask that issues flagged in this report be addressed. If you would like to provide feedback on the ScreenIT tool, please email the team at ScreenIt@bih-charite.de. If you have questions or concerns about the review process, please contact the PLOS One office at plosone@plos.org.

Reviewer #2: Summary

This manuscript reports a sequential explanatory mixed-methods study of attrition among patients on chronic antihypertensive therapy at Mulago Hospital, Uganda. The quantitative component is a retrospective cohort using routinely collected clinic records; the qualitative component comprises interviews with patients to contextualize disengagement from care. The topic is important and relevant for NCD program performance in a low-resource setting. The dataset appears sufficiently large and the mixed-methods design is appropriate. With several clarifications and analytic refinements, the work can meet PLOS ONE’s standard of technical soundness with transparent reporting.

Major comments (please address in revision)

1. Outcome definition & time origin. Attrition is defined as ≥2 consecutive missed appointments. Please specify the usual appointment interval (e.g., monthly/bi-monthly) and the exact time origin for survival analyses (e.g., clinic registration or first antihypertensive prescription) so readers can understand person-time construction and the practical meaning of “two consecutive” misses.

2. Survival modelling details. You report Kaplan–Meier and Cox (with proportional hazards checks and use of an extended Cox model when needed). Please: (a) state which variables violated PH and how you addressed this; (b) provide PH diagnostics (tests/plots) in the supplement; (c) describe model specification clearly candidate variables, criteria for entry/retention, handling of interactions and confounding.

3. Temporal alignment of blood pressure covariates. SBP/DBP measured at “last visit” are used as predictors. If serial measures exist, consider modelling SBP and DBP as time-varying covariates to avoid bias from values recorded close to the attrition event. If only fixed values are used, justify this choice and discuss limitations; a sensitivity analysis using baseline or penultimate-visit values would be helpful.

4. Scaling and interpretation of continuous predictors. Report the units for continuous covariates in the model (e.g., age per 1 or 10 years; SBP/DBP per 1 or 10 mmHg) and ensure the text, tables, and conclusions reflect the chosen scaling.

5. “Rate” vs “proportion.” Where you present the overall percentage disengaged, please refer to it as an attrition proportion/percentage. Reserve “rate” for person-time metrics (events per person-months/years) if you also estimate those.

6. Missing data. Beyond excluding records with high overall missingness, please describe variable-level missingness and your approach (complete-case, missing-indicator, or multiple imputation). If feasible, add a sensitivity analysis (e.g., multiple imputation) for key predictors.

7. Presentation of survival results. Add numbers-at-risk beneath Kaplan–Meier curves (or report in figure legends/tables), include log-rank p-values where curves are compared, and report median follow-up and total events to contextualize information content.

8. Qualitative reporting & integration. Methods are concisely described; to align with COREQ expectations, please expand on reflexivity (interviewer roles/position), sampling and recruitment, language/translation, and how thematic saturation was judged. A joint display linking quantitative predictors (e.g., distance/residence) to qualitative themes (transport costs, stock-outs, clinic processes) would strengthen integration and the discussion of mechanisms.

9. Calendar time and external shocks. Because disengagement may vary by year (e.g., service disruptions), consider modelling calendar period (or include it as a covariate) and/or discuss how temporal shocks could influence retention.

10. Contextual claims and citations. Where you compare observed retention/attrition to programmatic “targets,” please provide a supporting citation and clarify whether such targets apply specifically to hypertension care.

Minor comments (clarity, style, formatting)

• Ensure consistent terminology (e.g., “loss to follow-up” with hyphens; consistent use of BP/SBP/DBP).

• Standardize units and spacing (e.g., “mmHg”, “%”).

• In the setting description, use “intensive care” rather than “intensive” alone.

• Define all abbreviations at first use in the abstract and main text.

• Tables: label units and scaling in headers (e.g., “HR per 10 years of age,” “HR per 10 mmHg SBP”).

• Consider adding a simple flow diagram (records screened → eligible → included → retained vs LTFU/other outcomes).

Data, code, and reproducibility

The anonymized dataset provided in the Supporting Information is a strong step toward compliance with the PLOS Data policy. For maximal reproducibility, please also share the analysis code (e.g., do-files/scripts) and a brief data dictionary, ideally in a public repository with a stable link/DOI referenced in the Data Availability Statement.

Ethics

Ethical approvals and consent/waiver procedures are described. Please ensure the ethics section clearly distinguishes approvals for the retrospective records review and for the qualitative interviews (including consent procedures, language, and confidentiality safeguards).

Overall assessment

The research question is important, the design is appropriate, and the findings are potentially useful for strengthening hypertension services in similar settings. Addressing the analytic clarifications (survival modelling assumptions, covariate scaling and temporal alignment, missing-data handling), tightening terminology around “rate” vs “proportion,” and enhancing qualitative reporting/integration will substantially improve technical rigor and transparency. With these revisions, the manuscript should meet PLOS ONE’s criteria that conclusions be well supported by rigorously conducted and clearly reported analyses.

Reviewer #3: Thank you for this generally well written and interesting paper.

I have a couple of minor comments, and do believe the discussion needs to be looked into.

- Please provide the definition you used of Lost to follow up.

- Please provide an overview of variables extracted from patient files

- Please provide the topic guide and explain what topics were discussed during the interviews and if there was any theory the questions were based on.

- Please ensure LTFU is abbreviated the first time it's used and the abbreviation is used consistently.

- Please provide information about recruitment of participants for interviews: how were they identified, when and where were they asked to participate, what was sampling based on?

In terms of the discussion, the literature comparisons are not the clearest. There are some very long sentences with multiple studies addressed (see 344-350). Additionally, some of the explanations about why data you collected differed from literature data are insufficient, for example:

- Line 370: do you have a reference for this? Unsure what this is based on.

- Line 377 to 380: I am unsure what is meant here. Most patients being adult and elderly does not seem to be an explanation for age as a reason for loss to follow up. Please clarify.

- Line 381 to 387: This is unclear. Do you mean that time to attrition increases when systolic blood pressure increases, but decreases when diastolic blood pressure increases? That seems an interesting finding, why could that be? This is not discussed here, and the reasons provided don't seem very general, not specific for blood pressure measurements.

Line 388 to 392: You first mention PLWHIV is a similar population to your population, before explaining the difference in outcomes between your study and the study in China being due to the latter having a different population. Please rectify and provide additional reasons for the difference.

- Various discrepancies in the discussion section are explained due to the referenced studies having different populations. These studies may thus not be the best to compare your findings with and would be good to see if there are better suited studies out there, or maybe the data is not comparable as such and the paragraphs should be rewritten to reflect this.

Additionally the discussion is very long, particularly the comparisons with other scientific litertature is taking up a lot of space.

It would be good to reflect on some of your study strengths.

Conclusion

- the impact of COVID-19 is barely discussed in the discussion but mentioned in conclusion. Would be good to reflect on the impact of the pandemic in more detail in the discussion.

**********

what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

**********

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While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

Attachment

Submitted filename: report_10.1101+2025.06.27.25330319.pdf

pone.0327933.s007.pdf (597.6KB, pdf)
PLoS One. 2026 Feb 26;21(2):e0327933. doi: 10.1371/journal.pone.0327933.r002

Author response to Decision Letter 1


24 Nov 2025

Thank you for the thoughtful review and detailed feedback. We appreciate the comment and have addressed it in our revised submission. Although we updated the data availability section in the manuscript to include the public repository link, the portal version had not been updated. This has now been corrected and aligned. Thank you again for the opportunity to improve our work.

Attachment

Submitted filename: Rebuttal_letter_NN.docx

pone.0327933.s009.docx (35.3KB, docx)

Decision Letter 1

Ignatius Ivan

26 Jan 2026

Attrition and associated factors among patients on chronic antihypertensive therapy at Mulago hospital, Uganda: A mixed method study

PONE-D-25-33575R1

Dear Dr. Nathan Ntenkaire

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Ignatius Ivan, M.D

Academic Editor

PLOS One

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions??>

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #2: Yes

**********

Reviewer #2: Thank you for your careful and comprehensive revisions to the manuscript. The improvements made in response to the previous round of reviews have substantially strengthened the methodological clarity, analytical rigor, and interpretive coherence of the study

**********

what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy

Reviewer #2: No

**********

Acceptance letter

Ignatius Ivan

PONE-D-25-33575R1

PLOS One

Dear Dr. Ntenkaire,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS One. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

* All references, tables, and figures are properly cited

* All relevant supporting information is included in the manuscript submission,

* There are no issues that prevent the paper from being properly typeset

You will receive further instructions from the production team, including instructions on how to review your proof when it is ready. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few days to review your paper and let you know the next and final steps.

Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

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Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

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on behalf of

dr. Ignatius Ivan

Academic Editor

PLOS One

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Appendix. Detailed methodological sample size formulas for survival analysis.

    (PDF)

    pone.0327933.s001.pdf (114.8KB, pdf)
    S2 Appendix. Interview guide.

    (PDF)

    pone.0327933.s002.pdf (46.4KB, pdf)
    S3 Appendix. Graphical and statistical approaches used to assess for Cox PH assumptions.

    (PDF)

    pone.0327933.s003.pdf (421.5KB, pdf)
    S4 Appendix. Assessing for interaction.

    (PDF)

    pone.0327933.s004.pdf (183.2KB, pdf)
    S1 Table. Illustrative quotes linking each theme to representative participant responses.

    (PDF)

    pone.0327933.s005.pdf (205.8KB, pdf)
    S2 Table. Joint Display Linking Quantitative Predictors to Qualitative Themes.

    (PDF)

    pone.0327933.s006.pdf (201.8KB, pdf)
    Attachment

    Submitted filename: report_10.1101+2025.06.27.25330319.pdf

    pone.0327933.s007.pdf (597.6KB, pdf)
    Attachment

    Submitted filename: Rebuttal_letter_NN.docx

    pone.0327933.s009.docx (35.3KB, docx)

    Data Availability Statement

    All data and materials underlying the findings of this study are available in a public repository. The anonymized dataset, stata dofile, and data dictionary have been deposited in Zenodo and can be accessed at https://doi.org/10.5281/zenodo.17553717.


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