Modified dialectical behavior therapy–informed transdiagnostic intervention for emotional disorders: protocol for a randomized controlled trial

Abstract

Background

Anxiety and depressive disorders, characterized by high incidence and functional impairments, are emotional disorders with shared etiological and maintenance mechanisms. Dialectical behavior therapy (DBT) is a promising approach for the transdiagnostic treatment of emotional disorders. Developing a brief DBT intervention can facilitate the adoption of evidence-based therapy.

Methods

This protocol is for a 3-year single-blinded, two-arm randomized controlled trial. Individuals with depressive or anxiety disorder will be randomly allocated to a modified DBT–informed transdiagnostic psychotherapy group or a treatment-as-usual group. The intervention group will receive DBT individual therapy for 15 weeks. Power analyses revealed that the cohort should include a minimum of 250 participants. Preintervention, postintervention, and follow-up (after 3 months) assessments will be conducted. Primary outcomes will be severities of depression and anxiety rated by blind assessors. Intent-to-treat and per-protocol analyses will be conducted using the hierarchical linear model. Effect sizes will be estimated using Cohen’s d.

Result

To the best of our knowledge, the proposed study will be the first randomized controlled trial to evaluate the efficacy of a modified DBT intervention in managing transdiagnostic emotional disorders in Chinese individuals.

Conclusion

This intervention is expected to improve clinical outcomes, daily functioning, and quality of life. The trial will enrich the empirical evidence for transdiagnostic interventions, facilitating the implementation of evidence-based therapy and reducing the high prevalence and challenges (e.g., disability) of emotional disorders in the Chinese population.

Trial registration number

NCT05989451

Supplementary Information

The online version contains supplementary material available at 10.1186/s12888-024-06069-4.

Introduction

Epidemiological studies have reported that emotional disorders [1], such as anxiety disorders (e.g., generalized anxiety (GAD), social anxiety, and panic disorder) and depressive disorders (e.g., major depressive disorder [MDD] and persistent depressive disorder), exhibit the highest prevalence among mental disorders worldwide [2]. This situation has been exacerbated by the COVID-19 pandemic [3], with the global prevalence of depression reaching approximately 30%. Patients with depressive and anxiety disorders represent the largest group of individuals seeking treatment in mental health-care departments and have the longest treatment courses [4]. These disorders often lead to premature mortality, poor quality of life, and substantial functional impairment. Furthermore, the recurrence rates of depressive and anxiety disorders are considerably high, reaching up to 83% and 53%, respectively [5].

Depression and anxiety often coexist. More than half of MDD patients have a comorbid anxiety disorder (APA 2013). Patients with both MDD and anxiety have poor treatment outcomes [6] and exhibit increased suicidality [7]. The combinations of antidepressants and psychotherapy are more effective than antidepressant therapy alone in achieving response or remission [8]. However, a discrepancy can be noted between the demand for psychotherapy and its low prescription for anxiety and depression in Taiwan [9].

Since emotional disorders share comorbidities, primary mechanisms, or etiological processes, researchers have started focusing on transdiagnostic psychotherapy. Originally rooted in cognitive theories, transdiagnostic approaches were initially adopted for treating eating disorders [10]; their use was subsequently expanded to include anxiety [11] and depressive disorders [12]. As indicated the Diagnostic and Statistical Manual of Mental Disorders (DSM), Fifth Edition, transdiagnostic approaches focus on addressing the shared mechanisms of dysfunctional emotion processing (APA 2013; [13]. Among various transdiagnostic treatment approaches, the Unified Protocol (UP) has been widely adopted for treating emotional disorders [14]. UP is a cognitive behavioral therapy (CBT) that targets temperamental characteristics, particularly neuroticism, by substituting avoidant emotion regulation strategies with more adaptive ones. This protocol incorporates three core principles to address the commonalities among emotional disorders: enhancing emotional mindfulness, increasing cognitive flexibility, and reducing emotional avoidance. Although empirical evidence suggests the efficacy of UP in reducing anxiety and depressive symptoms, this protocol can effectively target only a few symptoms [15].

Emotional dysregulation is a fundamental psychopathological mechanism that is targeted by most third-wave CBT, such as dialectical behavior therapy (DBT), mindfulness-based cognitive therapy, and acceptance and commitment therapy. Owing to their inherently transdiagnostic framework and the potential of multicomponent interventions, the third-wave CBT view psychopathology as dimensions rather than categories, which allows for considerable flexibility and efficacy in identifications and treatments of emotional regulations among different shared comorbidities [16]. However, the studies on transdiagnostic third-wave CBT have several limitations, including methodological inconsistencies pertaining to the gold standard’s definitions (diagnoses outlined in the DSM or International Classification of Diseases [ICD]) and outcome measures, small sizes of the study cohorts, absence of comparison groups, or limited external replication of findings [17]. A substantial proportion of transdiagnostic studies have focused on only symptoms and not disorders. Some studies did not include diagnostic interviews for establishing definitive DSM/ICD diagnoses and thus failed to accurately diagnose specific mental disorders or comorbidities [17]. Thus, extensive research is needed in the domain of transdiagnostic psychotherapy.

Among third-wave interventions, DBT is a comprehensive, evidence-based approach for the treatment of pervasive emotion dysregulation. Originally developed for adults with borderline personality disorder (BPD) and chronic suicidality [18], DBT views dysfunctional behavior as either a consequence of dysregulated emotions or a maladaptive response to emotions. DBT incorporates proven techniques from classical cognitive behavioral approaches with elements of mindfulness and dialectical philosophy. Several studies have explored the outcomes of DBT-informed interventions customized for specific conditions beyond BPD, such as eating disorder, posttraumatic stress disorder, treatment-resistant depression, and substance use disorder [19]. These studies have yielded promising results, highlighting DBT as an effective transdiagnostic approach for regulating problematic emotions and behaviors. However, very few empirical studies have evaluated the efficacy of modified DBT against transdiagnostic emotional disorders [20]. Moreover, the use of the Western DBT model in Eastern populations, such as the Chinese population, raises questions regarding its validity and applicability [21]. Although standard DBT is effective, it is expensive and complex. From a service delivery perspective, a brief version of modified DBT is resource-efficient and cost-effective and can fulfill the unmet need for evidence-based therapy. On the basis of these considerations, we present the protocol of a 3-year randomized controlled trial for comparing clinical efficacy between the DBT-informed transdiagnostic intervention and treatment as usual (TAU) in patients with anxiety and depressive disorders. We anticipate that the modified DBT–informed individual therapy will outperform TAU in improving the anxiety and depression symptoms, daily functioning, and quality of life in patients with emotional disorders.

Study hypotheses

Our primary hypothesis is that compared with TAU, the DBT intervention would substantially reduce patients’ scores on the Hamilton Anxiety (HAM-A) and Hamilton Depression (HAM-D) scales.

Our secondary hypotheses are that the DBT intervention would outperform TAU in terms of various treatment outcomes measured by participants’ scores on the Difficulties in Emotion Regulation Scale (DERS); International Positive and Negative Affect Schedule-Short Form (I-PANAS-SF); Schedules for Clinical Assessment in Neuropsychiatry (SCAN) interview; 9-item Patient Health Questionnaire (PHQ-9); 7-item Generalized Anxiety Disorder (GAD-7) scale; 21-item Depression, Anxiety, Stress Scales (DASS-21); Penn State Worry Questionnaire (PSWQ); Social Phobia Scale (SPS); Panic Disorder Severity Scale (PDSS); Work and Social Adjustment Scale (WSAS); Quality of Life Enjoyment and Satisfaction Questionnaire-Short Form (Q-LES-Q-SF); and DBT Ways of Coping Checklist (DBT-WCCL).

All hypotheses will be tested through an intention-to-treat analysis to preserve the effect of randomization.

Methods

Design and setting

We will conduct a single-blinded, two-arm randomized controlled trial in the psychiatry departments of Mackay Memorial Hospital. Study participants will be allocated into two parallel groups at a 1:1 ratio: intervention (modified DBT–informed individual therapy) or control (TAU) groups. Preintervention, postintervention, and follow-up (after 3 months) assessments will be conducted. The study will follow the CONSORT (Consolidated Standards of Reporting Trials) statement [22] and SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) guidelines [23].

Participants

Inclusion criteria

The inclusion criteria will be as follows: aged 18 ∼ 60 years, able to provide informed consent, proficient in Mandarin Chinese (to a degree that allows them to complete the study questionnaire), and have a SCAN-based diagnosis of depressive or anxiety disorder. Individuals will be recruited if they fulfill the ICD criteria for one of the following disorders: depression (F32 and F33), persistent mood disorder (F34), phobic anxiety disorder (F40), other anxiety disorder (F41), and adjustment disorders (F43.2). Individuals receiving a score of ≥ 10 on the PHQ-9 or GAD-7 scale at the initial screening interview will be assessed using the 17-item HAM-D and HAM-A scales. Individuals with a score of ≥ 14 on the HAM-D or HAM-A scale will be subjected to the preintervention assessment involving the SCAN interview. Patients are expected to have multiple comorbidities. Thus, to avoid study complexity, we will not stratify the participants by their comorbidities.

Exclusion criteria

We will implement the following exclusion criteria: having intellectual disability, a history (within the previous 3 months) of substance use disorder, bipolar disorder, psychotic disorder, organic brain disorder, acute suicidality or a history of frequent or recent suicide attempts, a recent history (within previous 6 weeks) of changes in psychiatric medications or unwillingness to maintain stable medication dosages during the proposed study, a history (within the previous 5 years) of ≥ 5 sessions of CBT or unwillingness to stop concurrent psychotherapy for an emotional disorder, a mental or physical condition necessitating hospitalization, or a medical condition likely to prevent participation in the proposed study. To maintain similarity with a real-world scenario, we will not exclude patients whose medications are altered (if the attending clinician deems it necessary or it is clinically crucial) during the trial. Instead, we will include a question for the referring or attending clinicians to obtain information on medication changes.

Procedures

Figure 1 presents the CONSORT diagram depicting the timelines for patient recruitment and assessments. We will include adults with depressive or anxiety disorders seeking treatment at Mackay Memorial Hospital who agree to participate in the proposed study.

Fig. 1.

Recruitment, assessment, and follow-up process using the CONSORT diagram

Participant recruitment

Eligible individuals will be recruited by research assistants in waiting rooms outside the clinics, through referrals from attending clinicians, and through advertising (flyers, posters, and the Internet [social media and electronic discussion boards]). An initial screening interview will be conducted with patients willing to participate in the proposed study. Subsequently, a semi-structured diagnostic interview will be conducted with eligible individuals providing informed consent. The participants will also complete the preintervention, postintervention, and follow-up assessments (Table 1). Interrater reliability will be estimated by principal investigators (psychiatrists). The κ scores for the SCAN, HAM-D, and HAM-A will be monitored on a regular basis and maintained at a target consistency level of ≥ 0.70.

Table 1.

Assessment schedules

Procedure	Study Period
	Enrollment	Pretreatment	Posttreatment	3-month follow- up
Screening interview
Eligibility screening	V
Informed consent	V
Sociodemographic information
Date of birth, sex, job, education, job, marital status	V
Diagnostic interview
Full SCAN		V
Abbreviated version SCAN			V	V
Primary outcomes
HAMD-17		V	V	V
HAM-A		V	V	V
Clinical response
CGI-S		V	V	V
CGI-I			V	V
Disorder-specific measures
DASS-21		V	V	V
PHQ-9		V	V	V
GAD-7		V	V	V
PDSS-SR		V	V	V
PSWQ		V	V	V
SPS-C		V	V	V
Transdiagnostic measures
DERS		V	V	V
PANAS-SF		V	V	V
Q-LES-Q SF		V	V	V
WSAS-C		V	V	V
DSS of DBT-WCCL		V	V	V

Randomization

Randomization will be performed using a random number generator (www.randomizer.org) to ensure an equal distribution of the participants between the intervention and control groups. The assessors will be blinded to group allocation (to be performed by an independent researcher) and will remain blinded during assessments before and after the trial. The revealing of participants’ status will be performed after the completion of the whole trial.

Mediation and instrumental variables

Upon completion of the intervention and follow-up assessments, we will conduct a mediation analysis to explore the potential mechanisms and mediators that influence treatment outcomes—scores on the HAM-D and HAM-A scales. We hypothesize that improvements in depression, anxiety, daily functioning, and quality of life would be mediated by improvements in coping and emotional regulation skills—scores on the DBT-WCCL and DERS, respectively.

Study groups

Control group

TAU—the current daily practice of psychiatrists in Taiwan typically includes the prescription and monitoring of drugs (e.g., antidepressants and/or anxiolytic medications), psychotherapy (e.g., empathic listening, supportive counseling, and psychoeducation), or both. Individuals who have been receiving one of these treatment options will be included in the control group and continue to receive the same treatment.

Intervention group

The modified DBT–informed intervention, developed by the principal investigators (PI) and coinvestigators, will be administered during 15 individual therapy sessions (duration: 50 ∼ 60 min/session). These sessions adhere to the manual, retaining the essence of DBT [24], and maintaining a dialectical focus. Each session focuses on specific DBT skills within the module contents (Table 2). At least one new skill will be taught in each session. Considering patient requirements, the attending therapists can teach 2 to 3 additional skills that are relevant and suitable. The module contents will include instructions on skill use; structured exercises, feedback, and homework; information on behavior modeling, activation, and shaping; skill use in a real-world environment (generalization); and troubleshooting. Several modifications have been made to the original DBT framework. Some contents have been eliminated for conciseness and time-efficiency; hence, the emotional regulation module will require only 5 weeks; the interpersonal effectiveness module will require only 2 weeks; the distress tolerance module will require only 3 weeks. The intervention duration is reduced from 48 to 15 sessions. As shown in Table 2, the DBT mindfulness concept will be taught in the first and second sessions. During each session, the participants will engage in mindfulness exercises, such as breathing meditation, body scan meditation, informal mindfulness practices involving the five senses, mindful movement, wise mind, urge surfing, and practicing compassion for others.

Table 2.

Session-by-session summary of the personalized, modified DBT–informed intervention

	Module	Selected skills	Session content	Worksheets for homework
1	Mindfulness: “what skills”	Psychoeducation and enhancing motivation and mindfulness	Establishing relationships: Discussing core problems and treatment goals and enhancing patients’ motivation to change Teaching mindfulness-related skills: observation, description, and participation	Mindfulness Worksheet 2
2.	Mindfulness: “how skills”	DBT mindfulness and biopsychosocial theory	Establishing relationships: Discussing core problems and treatment goals and enhancing patients’ motivation to change Linking patients’ problems to DBT’s biopsychosocial theory. Selecting one problem behavior for behavior/chain analysis Teaching mindfulness-related skills: nonjudgment to internal experiences, one mindful, and effective	Mindfulness Worksheet 2 General Worksheet 2 (Analyzing problem behavior: chain analysis)
3.	Emotional regulation	Describing emotions	Clarifying the functions of emotions and helping patients identify emotions, particularly sadness and fear	Emotional Regulation Worksheet 4
4.		Fact-checking	Facilitating cognitive identification and teaching skills to address cognitive challenges and changes	Emotional Regulation Worksheet 5
5		Choosing opposite actions or problem-solving approaches	Explaining how to decide whether to use opposite actions or problem-solving approaches	Emotional Regulation Worksheet 6
6		Opposite actions	Explaining the contents of opposite actions for emotions, particularly sadness and fear (may include exposure therapy)	Emotional Regulation Worksheet 7
7		Problem-solving approaches	Explaining and reviewing the contents of problem-solving approaches for emotions, particularly sadness and fear	Emotional Regulation Worksheet 8
8		ABC PLEASE	Teaching how to accumulate positive experiences, build mastery, and cope ahead Teaching skills to manage and reduce emotional vulnerability	Emotional Regulation Worksheet 9
9	Distress tolerance	STOP and TIPS	Teaching how to manage biological/experiential changes and regulate attention through TIPS and paired muscle relaxation	Distress Tolerance Worksheet 4 or 4a
10		Distracting with Wise Mind and ACCEPTS	Teaching skills for regulating attention by distracting oneself, self-soothing, improving moments, and analyzing pros and cons	Distress Tolerance Worksheets 5–7
11		Radical acceptance (prepare for termination)	Inducing cognitive changes through skills such as radical acceptance, willingness, half-smile and willing hands, and mindfulness	Distress Tolerance Worksheet 12
12	Interpersonal effectiveness	Goals and priority setting (prepare for termination)	Ensuring that patients are aware of their priorities (goals/objective, relationship, and self-respect) DEAR MAN: assessing objective relationships Changing behaviors with reinforcement (selection)	Interpersonal Effectiveness Worksheets 3 and 14 (if have time)
13		GIVE, FAST, and the Dime Game (prepare for termination)	GIVE: assessing relationship effectiveness FAST: assessing self-respect effectiveness Teaching how to strongly ask or say no	Interpersonal Effectiveness Worksheets 4 and 6
14		Interpersonal validation (prepare for termination)	Teaching how to validate others and oneself	Interpersonal Effectiveness Worksheets 12 and 13
15	Review and termination	Discuss termination	Reviewing patient progress, therapeutic relationships, goals (whether achieved or not), and the most and least helpful aspects of therapy Assessing whether patients feel satisfied and proud of their progress at therapy termination

Worksheets or homework modules were prepared on the basis of the DBT Skills Training Handouts and Worksheet second edition, which were written by Professor Marsha M. Linehan and published by Guildford Press. The materials were translated into Mandarin Chinese by DBT therapists from MacKay Memorial Hospital and published by the Living Psychology Publishers Co. DBT, dialectical behavior therapy

As shown in Table 3, a typical session is structured as follows. During the first 5 ∼ 7-min period, attending therapists will greet patients, address their mood disturbances that might interfere with the therapy session, and review the patients’ diary cards to organize the outlining the primary behaviors or skills to be focused during the session. The therapists will introduce and invite the patient to practice a new mindfulness exercise in the next 5 min. The therapists will then allocate 5–10 min to explore the chain of events or behaviors that interfere with patient conditions or therapy. In the next 10 min, skills and homework from previous sessions will be reviewed and link the obtained insights to any crisis or event that might have triggered emotional dysregulation. The therapists will introduce a new skill and conduct practical exercises that are directly linked to solve the crisis or event of the week. The therapists will then present example worksheets, assign homework, and obtain patients’ commitment to practice the new skill outside the therapy room. The remaining session will be dedicated to address patient questions or help the patients troubleshoot potential obstacles to implementing a skill. These approaches will lead to acceptance and changes to help develop self-awareness, thereby facilitating the construction of new meanings in life.

Table 3.

Content and duration of each session of the personalized, modified DBT–informed intervention

	Duration (min)	Content	Summary
1.	3	Greeting and attending	Greet and attend to initial or deteriorating mood that interferes with therapy and mindfulness practice
2.	2	Diary card (overall) review	Review the diary card after greeting and convey its importance and the skills practiced by patients
3.	1–2	Organization	Organize the session in accordance with the primary behavior or skill to be taught
4.	5	Teaching mindfulness	Introduce and practice a new mindfulness skill
5.	5–10	Behavior/chain analysis of emotions or problematic actions	Explore the chain of events or behaviors that interfere with patient condition or therapy
6.	10	Homework review	Review the previous session’s skills and provide feedback on the previous week’s homework (skill practice). To link to the crisis or event that caused emotional dysregulation during the week in question.
7.	15	Teaching new skills	Introduce a new topic and skill domain; discuss and practice the skill in relation to the crisis or event of the week
8.	5	Worksheet and homework: practicing new skills	Present worksheets, assign homework, and demonstrate how to apply relevant skills and cope with crises or events that cause emotional dysregulation
9.	2	Skill use in the real world	Evaluate patients’ commitment to practicing skills, completing homework, and using such skills in the real world
10	2	Troubleshooting	Address questions or help troubleshoot potential obstacles to implementing a skill

DBT, dialectical behavior therapy

Therapist training and supervision

The intervention will be delivered by DBT therapists who have received specialized training in this treatment package. These therapists are mental health professionals with various backgrounds—psychiatrists, psychologists, and psychiatric social workers—who have received DBT training and have clinical experience in treating emotional disorders. During the trial period, the therapists will attend weekly peer and expert supervision sessions through online conferences or face-to-face meetings. The therapists will submit written case reports, treatment plans, and therapy progress. Peers and experts will solve problems and challenges encountered during a session and ensure that the therapy is administered in accordance with the protocol, thereby maintaining the quality of the intervention. All treatment sessions will be audio-recorded. To measure protocol adherence, we will randomly assess 10% of the recorded data, stratified by therapist and patient. These assessments will be performed by a DBT adherence coder (Co-PI: Dr Wu).

Training and reliability assessments

The interrater reliability will be calculated according to SCAN, HAM-A, HAM-D, and Clinical Global Impressions interviews. To maintain agreement and prevent drifts among interviewers regarding the use of these semi-structured instruments, monthly reviews will be held. Potential sources of diagnostic disagreements will be thoroughly discussed calibrated.

Interviews and outcome measures

Table 1 presents the outcome measures and assessment schedules. The PHQ-9 and GAD-7 scale will be administered every week before the therapy session.

Diagnostic assessment

The semi- structured SCAN interview (Schedules for Clinical Assessment in Neuropsychiatry) will be conducted to diagnose Axis I disorders. Diagnoses will be assigned a clinical severity score ranging from 0 (no symptoms reaching clinically significant severity) to 4 (symptoms severely interfering with or disrupting daily functioning), which will serve as the clinical threshold for diagnosis. In cases where two diagnoses are found to be equally interfering, both will be marked as coprincipal diagnoses. The complete SCAN interview will be administered at preintervention. Its abbreviated form focusing on current symptomatology will be administered after the intervention and at the 3-month follow-up. The Chinese version of the SCAN has good reliability and validity and has been widely used in our previous research [25].

Clinician-rated measures at preintervention, postintervention, and 3-month follow-up

The 17-item HAM-D scale (Hamilton Depression Scale) is used in MDD-related clinical trials to assess the severity of depression [26]. The Chinese-translated version of the 17-item HAM-D exhibits good internal reliability and concurrent validity.

The HAM-A scale (Hamilton Anxiety Scale) is used to measure the severity of anxiety. It’s Chinese version exhibits good interrater reliability and validity [27].

The Clinical Global Impressions-Severity (CGI-S) and Improvement (CGI-I) scales are used to measure disorder severity and global improvement, respectively. The CGI-S (severity) helps assess patients’ current conditions; responses are rated on a scale with end points ranging from 1 (normal) to 7 (most severely ill). The CGI-I helps measure the degree of improvement on a scale ranging from 1 (substantial improvement) to 7 (substantial deterioration) [28].

Disorder-specific measures

The DASS-21(Depression, Anxiety, and Stress Scales) is a self-report questionnaire that helps measure the levels of depression, anxiety, and stress. This tool exhibits favorable psychometric properties. Higher scores indicate higher levels of depression, anxiety, and distress [29]. The Chinese version of the DASS-21 is a reliable and valid instrument.

The PHQ-9 (Patient Health Questionnaire- 9 items) is a 9-item self-rated questionnaire that helps measure the severity of depressive symptoms in accordance with the DSM-IV criteria for MDD. The Chinese version of the PHQ-9 exhibited good reliability and validity [30].

The GAD-7 (Generalized Anxiety Disorder-7 items) is a 7-item self-rated questionnaire that helps measure the severity of GAD in accordance with the DSM-IV diagnostic criteria. In addition, it can help assess panic disorder. This scale has been demonstrated to exhibit good reliability and validity in Chinese patients [31].

The PDSS (The Panic Disorder Severity Scale-Self Rating) is a self-report instrument that helps measure the overall severity of panic disorder [32]. A higher score indicates a higher severity of panic attack. This scale has been validated in the Chinese population.

The PSWQ (Penn State Worry Questionnaire) is a self-report measure of worry and GAD and has been used in most studies assessing the outcomes of GAD treatment. The total score is calculated by summing the scores for the first 11 items and the reverse scores of the remaining 5 items. Psychometric properties and factor structure of the Taiwanese version of the PSWQ have been reported [33].

The Chinese version of the SPS (Social Phobia Scale) (SPS-C) comprises 12 items and helps measure social anxiety. The SPS-C has been validated in the Taiwanese population [34].

Transdiagnostic measures

The 35-item Difficulties in Emotional Regulation Scale (DERS) helps assess difficulties in regulating emotions across six domains [35]. A higher score indicates a higher level of emotion dysregulation. The Chinese version of the DERS has been validated; it exhibits good internal consistency and test–retest reliability.

The I-PANAS-SF (International Positive and Negative Affect Schedule Short Form) contains two 10-item mood scales that help measure positive and negative affect. The I-PANAS-SF has been widely used and exhibits good validity and reliability in the Chinese population [36].

The Stressful Life Events Questionnaire (https://www.ptsd.va.gov/professional/assessment/te-measures/stress-life-events.asp) is a 13-item self-report tool that helps assess patients’ physical health losses; financial difficulties; and conflicts with parents, peers, or friends.

The Q-LES-Q-SF (Quality of Life Enjoyment and Satisfaction Questionnaire- Short Form) is a self-report questionnaire (Endicott et al. 2006). A higher score indicates higher levels of enjoyment and satisfaction with life. The Chinese version of the Q-LES-Q-SF has been validated in primary care [37].

The WSAS (Work and Social Adjustment Scale) helps measure functional impairment due to a health problem. The Chinese version of this scale has been validated; it was demonstrated to be a reliable and valid instrument [38].

The DBT Skills Subscale (DSS) of the DBT- Ways of Coping (DBT-WCCL) is a 38-item subscale that helps measure the frequency of using DBT skills (in response to stressors) over the previous month. Responses are rated on a 4-point Likert-type scale with end points ranging from 0 (never used) to 3 (regularly used). This instrument is reliable and valid and can differentiate between individuals who receive DBT skills and those who do not [39].

The Treatment History Interview questionnaire helps assess patients’ descriptions of psychotherapy administered during a study (Linehan & Heard, unpublished 1987 manuscript). This questionnaire has been used in several studies on DBT (Linehan et al., 2006; Linehan et al., 1993; McMain et al., 2012; McMain et al., 2009) and has been translated (and validated) into Chinese. The Chinese version of this questionnaire exhibits good feasibility. Using this scale, we will gather self-reported data on patients’ visits to outpatient or emergency departments for suicidal ideation or attempts in the previous 4 months. The assessments will be performed at preintervention and follow-up.

The Five Facet Mindfulness Questionnaire (FFMQ) helps measures five aspects of mindfulness: observation, description, awareness, nonjudgment of internal experiences, and nonreactivity to internal experiences [40]. The Chinese version of this questionnaire exhibits good psychometric properties, similar to those of the English version.

Health economics

To evaluate the cost and clinical efficacy of the modified DBT–informed intervention and TAU, we will estimate the time lost due to absence from work and the costs of outpatient visits, emergency visits, or hospitalizations.

Assessment of outcome mediators

The I-PANAS-SF, DERS, Q-LES-Q-SF, and DBT-WCCL were administered during the intervention and follow-up periods. The measured variables will be explored as mediators to evaluate their potential mediating effects.

Evaluation of moderating effects

Demographic information, diagnoses outlined in the DSM-5, and scores on the Stressful Life Events Questionnaire will be used to evaluate the moderating effects.

Statistical analysis

General considerations

The research assistant will manage data and check for errors by using IBM-compatible computers (available at the Psychological and Behavioral Science Research Laboratory of Mackay Memorial Hospital). The data double entry process will be supervised by the staff at the Psychological and Behavioral Science Research Laboratory who have extensive experience in managing large data sets for both clinical trials and longitudinal studies. Once the data are entered and checked for errors, analyses will be conducted using SPSS.

Power analysis

A priori power analysis performed using G*Power indicated the need for at least 176 (88 in each group) participants to achieve statistical power for detecting a medium effect size of 0.35, on the basis of the literature, with an alpha value of 0.05, power of 80%, and repeated measures correlation coefficient of 0.5. To account for an expected dropout rate of 30%, we will recruit 250 participants.

Data analysis

All data will be subjected to an intent-to-treat analysis (n = 250) based on treatment assignment, irrespective of whether the participants complete the intervention. In addition, a per-protocol analysis will be conducted using data from participants who have completed > 8 sessions of the intervention and relevant assessments after group allocation. To test the adequacy of randomization, we will conduct between-group comparisons of all baseline characteristics by using the t test for continuous variables and the chi-square test for categorical variables.

Between-group differences in mean changes (from preintervention to postintervention) in the primary outcomes (HAM-D and HAM-A scores) will be analyzed through repeated measures analysis of variance by using a between-subject factor (treatment), a within-subject factor (time), and an interaction term (time × treatment). Additional analyses will be performed using mixed models adjusted for baseline covariates. This model, when adjusted for baseline severity and between-site difference, will provide an estimate of the group effect. Between-group differences will be analyzed using hierarchical mixed-methods models for continuous variables (scores on the HAM-D, HAM-A, CGI-S, and all self-reported tools) measured at preintervention, postintervention, and 3-monthfollow-up. The models will include random intercept, random slope, and fixed effects for treatment. Mixed-effects logistic regression will be performed to evaluate changes in diagnostic status.

For the noncontrolled extension part of the study, we will perform the paired-samples t test to assess changes from preintervention to postintervention and follow-up. Repeated measures analysis of variance will be performed to analyze changes in the participants’ symptom scores from preintervention to postintervention and follow-up. The primary outcomes will be HAM-A and HAM-D scores, and the secondary outcomes will be their transdiagnostic outcomes (DERS and I-PANAS-SF), clinical severity (SCAN interview), clinical response (CGI-S and CGI-I), principal diagnoses (PHQ-9, GAD-7, DASS-21, PSWQ, SPS-C, and PDSS), functional impairment (WSAS), quality of life (Q-LES-Q SF), and mechanisms of changes (DBT-WCCL).

Mechanisms, instrumental variables, and causal relationships

To determine causal relationships, we will investigate the direct or indirect effects of potential mediators on the exposure. The DERS and DBT-WCCL will be used to explore potential causal mechanisms underlying treatments and changes in the severity of anxiety or depression. Initially, no unobserved confounders will be assumed; subsequently, a joint model containing all mediators and independent variables will be used.

Data collection and management

Paper-based data will include information obtained using self-reported and clinician-rated questionnaires at each assessment point. These data will be entered twice into the ACCESS system to ensure validity and reliability. Electronic data will include information derived from the hospitals’ electronic records. These data will be collected and securely encrypted.

Adverse events and study termination

The therapists will maintain their routine monitoring of adverse events during clinical visits. A blind interviewer will conduct additional monitoring of possible adverse events due to treatment. The PIs will monitor and assess severe adverse events and immediately report them to the relevant institutional review boards. PIs will discuss severe adverse events with the affected participants and the attending clinicians after obtaining patient permission. Participants are allowed to request and undergone a discontinuation anytime during the trial.

Ethical considerations

Informed consent

The nature and extent of human subject involvement is outlined in the research plan. The participants must be capable of understanding the nature of the proposed study, which will be explained in full by the project staff. The staff will also explain potential risks and benefits and request the participants to sign an informed consent form.

Ethical approval

All procedures will be performed in accordance with the ethical standards of the relevant national and institutional committees on human experimentation and with the ethical principles of the Declaration of Helsinki (2008 amendment). This study has been approved by the Institutional Review Board of Mackay Memorial Hospital (22MMHIS451e).

Protection of confidentiality

Data confidentiality and anonymity will be maintained throughout the study period. Data will be transmitted only in the pooled form and used solely for research purposes. The participants will be assigned codes for identification. In the event that hospital accrediting agencies inspect medical and research records, the investigators will take reasonable measures to ensure that no copied data contain any identifying information.

Feasibility

Regarding the training and clinical practice of DBT therapist, the therapists at Mackay Memorial Hospital have been providing standard DBT (since 2010) to patients with BPD and a history of suicide attempts.

Our study will reveal the outcomes of a modified DBT–informed brief intervention for treating emotional disorders in Taiwan. In addition, we will examine the feasibility and acceptability of specific elements of the intervention. Using these data, we will refine the intervention delivery method and DBT mode to optimize the transdiagnostic approach.

Discussion

We aim to explore the outcomes of a modified DBT–informed individual psychotherapy for treating patients with transdiagnostic emotional disorders in Taiwan. We will examine the feasibility and acceptability of specific elements of the intervention program. On the basis of the findings, we will refine the methods of delivering the intervention and the mode of DBT. The proposed randomized controlled trial will help achieve the following objectives.

Theoretical benefits

The transdiagnostic intervention is expected to have a high clinical practicability. It will simplify the process of clinical training and facilitate the implementation of evidence-based psychotherapy. The proposed study will fill the gap in the current literature offering insights into the efficacy of a brief, modified DBT–informed transdiagnostic individual psychotherapy against emotional disorders. The findings will widen treatment providers’ perspectives beyond diagnosis. In the proposed study, therapists would benefit from learning and familiarizing themselves with key aspects of treatment progress. Our findings will provide empirical evidence for Asian therapists, sealing the gap in the literature on clinical outcomes of transdiagnostic psychotherapy in patients with emotional disorders. The proposed study will improve clinicians’ knowledge regarding the implementation of the modified DBT approach in Chinese individuals with other emotional disorders.

Potential benefits for patients

The proposed study will alleviate the participants’ anxiety and depressive symptoms. Approximately 100 patients will receive the modified DBT–informed transdiagnostic psychotherapy. If effective, the brief intervention will reduce the overall treatment duration and cost, ameliorate clinical symptoms, and improve the quality of life.

Expected contributions

The proposed study will substantially contribute to the academia by providing empirical evidence for the adoption of transdiagnostic interventions, particularly in Taiwan, where few studies have focused on this topic. Testing the proposed hypotheses will reveal differences in clinical outcomes between the intervention and control groups. Subgroup analyses by sex, diagnosis, or comorbidities will be conducted to determine between-group differences in treatment outcomes. In terms of academic implications, the proposed study will provide valuable insights into the efficacy and feasibility of psychotherapy for Mandarin-speaking patients with transdiagnostic emotional disorders, which is an underexplored field. In terms of clinical implications, the modified DBT approach has high clinical practicability and can simplify clinical training and promote evidence-based psychotherapy.

Design implications and limitations

A major limitation of the proposed study is that the control group will receive TAU. In other words, the study will lack an active comparator group. Considering the possibility that participants receiving TAU have received or are receiving other forms of psychotherapy, we will specifically instruct the control group members to continue to these services as usual. In the intervention group, we will not include patients who have received ≥ 5 sessions of CBT in the previous 5 years or those unwilling to stop the concurrent psychotherapy for their emotional disorders. Given that patients undergo medication switching in real-world conditions, we will not exclude patients whose attending clinicians prescribe any changes in medications. However, for further analysis, we will collect data on medication changes and enquire the clinicians about the reasons or indications for such changes. Another potential research obstacle is that therapists from the participating hospitals have routine clinical work during work hours. The usual rule in these hospitals is that the research work must be independent of original clinical services. To address this challenge, therapists will treat participants during off-duty hours (in the evenings or weekends). Hence, the therapists’ payments for serving during off-duty hours are included in the estimated research cost.

Expected progress

The researchers and therapists required 3 months (August to October 2023) to be familiarized with study measures and the treatment protocol. Participant recruitment, randomization, and outcome assessments will be conducted from October 2023 to January 2026. During the enrollment period, 250 participants will be enrolled and randomized into the intervention and control groups; each group will comprise 120 participants. The intervention or TAU will be administered from February 2024 to April 2026. Data will be collected at three time points from October 2023 to July 2026. Approximately 180 and 130 participants will undergo postintervention and follow-up assessments, respectively.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Author contributions

Shu-I Wu and Shen-Ing Liu designed the study and drafted the protocol. Shu-I Wu completed the first draft. All authors contributed to the writing and have approved the final version of the manuscript.

Funding

The proposed study is supported by the National Science Council (grant number: 112-2314-B-195-007-MY3) and Mackay Memorial Hospital (grant number: MMH-113-20). SIW is part-funded by the Department of Medical Research, Mackay Memorial Hospital (MMH-113-19, MMH-MM-11103, MMH-111-51, MMH-MM-11002, MMH-110-110, MMH-109112, MMH-10914). The funders had no roles in study design, data collection and analysis, decision to publish, or preparation of the manuscript. None of the authors or their spouses have any financial relationship with the funding body.

Data availability

Datasets being analyzed and results being generated and reported in this article are not publically available due to protections of personal privacy. Restrictions applied to these data, which were used under license for our study, and so are not publicly available for duplication. Further data analysis may be requested after discussion with authors. If anyone would like to request data from this study, they can do so from the corresponding author.

Declarations

Ethics approval and consent to participate

Institutional Review Board of Mackay Memorial Hospital (approval number: 22MMHIS451e). We will include adults with depressive or anxiety disorders seeking treatment at Mackay Memorial Hospital who agree to participate in the proposed study.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.