Study setting and participant recruitment

Participant recruitment began in September 2023 and will continue until March 2025 from CHAT, Centre of Excellence for Youth Mental Health, a community-based youth mental health outreach and assessment service under IMH in Singapore. CHAT was established to provide free and confidential access for early treatment among young people aged 16–30.25 CHAT adopts the clinical staging model developed by Patel et al26 27 for assessing severity of mental health syndromes and disorders to facilitate a tiered, stepped-care approach to providing corresponding intervention intensities.14 Trained case managers will conduct a structured mental health assessment and clinical interview with clients to determine participant eligibility.

Participant eligibility

Clients are eligible to participate in the trial if they are aged 16–30 and are assessed to have general psychological distress (stage 1a), subsyndromal or subthreshold symptoms (stage 1b), or are experiencing a first episode of a mood disorder (stage 2). All sexes, genders, races or nationalities are eligible. Clients will be excluded from the trial if they have more severe or treatment-resistant mental health disorders (stage 3 or 4); high suicidal risk (determined by the Columbia Suicide Safety Rating Scale)28 (online supplemental appendix 3); or active positive psychotic symptoms (eg, hallucinations, delusions). Referrals to appropriate treatments and level of psychiatric care will be made according to IMH’s protocol. Clients will also be ineligible if they have significant intellectual disability or cognitive impairments; have active psychotherapy or pharmacotherapy; are younger than 21 years and do not have parental consent to participate in the study; or decline to be registered as a client at IMH if they are randomised to the intervention arm. Only English-speaking and English-literate participants will be invited, as the intervention and certain questionnaires are only available in English; this is unlikely to be limiting as most clients are English literate.

Eligible participants will be referred to the study’s research coordinator who will obtain written informed consent (online supplemental appendix 1). Parental consent will be taken for clients younger than 21, which is the age of consent in Singapore. Participants will be informed that if they are randomised to the intervention arm, they will be required to attend six intervention sessions, and register as a client in IMH.

Sample size calculation

For a fully powered, two-arm randomised trial (statistical power 0.80, type 1 error rate 0.05), we estimate needing 47 participants per arm to reject the null hypothesis with a moderate effect size of 0.50 on the primary outcome (psychological distress) for the intervention group, and assuming an effect size of 0.15 response for the control group based on the rate of spontaneous remission of symptoms. Accounting for a 30% attrition rate based on the pilot data,23 62 participants will be prospectively recruited per arm, resulting in a total of 124 participants. This recruitment target is feasible given that CHAT assessed 930 individuals in 2022.29 Reasons for attrition will be analysed and retention strategies (eg, simplifying procedures to reduce participant burden) will be implemented to minimise high attrition.

Intervention assignment and blinding

Participants will be assigned to either SFBT (intervention) or case management (TAU) in a 1:1 ratio determined by a computer-generated simple randomisation sequence managed by an off-site statistician. The statistician will place each random number within individual sealed, opaque envelopes labelled with a participant number sequence. After obtaining consent, a research coordinator will assign the participant to the respective arm by opening one envelope. The research coordinator will then assign a case manager to participants based on the final arm allocation. The case manager will contact the participants within five working days of receiving informed consent. Participants in the intervention arm will have their case reviewed by a psychiatrist after contact by the case manager. The principal investigator, research coordinators, clinical supervisors, case managers and participants will be aware of the intervention being received. The statistician conducting data analysis will be blinded to the treatment arm allocation.

Interventions

Participants in the intervention arm will receive six weekly sessions of SFBT, each lasting 45–60 min, delivered virtually or in person by six IMH case managers certified as solution-focused practitioners by the International Alliance of Solution-Focused Teaching Institutes (IASTI). Certification is based on completing intensive didactic and experiential training, self-study, individual supervision from a Master level certified SFBT therapist, and meeting competency benchmarks on an oral examination. Case managers will deliver a manualised version of SFBT that includes problem description, co-construction of therapy goals, exploration of clients’ preferred outcomes, and identification of previous solutions and resources in solution building. SFBT will be personalised according to process evaluation measures that assess treatment engagement and experience. The Outcome Rating Scale (ORS)30 31 will be administered at the start of sessions and assesses four areas of life functioning: individual well-being, interpersonal well-being, social role, and overall well-being. The Session Rating Scale (SRS),32 ,33 a measure of therapeutic alliance, will be administered at the end of each session to identify and address problems in real time. As part of the intervention protocol, measures will be interpreted in-session with the participant to collaboratively assess treatment progress. After completing six sessions, if participants demonstrate a treatment response in decreasing psychological distress, they will terminate care and receive a summary of their strengths, goals and subsequent steps. Those who continue to experience high psychological distress or deterioration in psychological symptoms (as determined by clinicians and verified by measures) at the end of the 6-week intervention will be referred to psychiatric or community counselling services. Throughout the study, case managers delivering SFBT will receive monthly group clinical supervision with a Master level certified SFBT therapist to ensure intervention compliance and discuss treatment goals and strategies.

The TAU group will receive routine case management, comprising weekly 10 to 45 minute-long phone calls. The goal is to provide care coordination and referrals to appropriate psychiatric or community therapy services. Case management will continue until contact with psychiatric services is established, which averages 10 weeks.29 Case managers will focus on five key activities: (1) assessing the participant’s mental state and biopsychosocial needs; (2) co-developing individualised action plans; (3) coordinating resources to actualise the plan; (4) monitoring the participant’s progress; (5) reviewing the outcomes and the overall effectiveness of the effort before termination. TAU differs from SFBT by focusing on assessing present mental health symptoms and maintaining clients in the help-seeking process, rather than guiding clients in future and recovery oriented, goal-directed problem solving. TAU does not include active therapeutic strategies, such as problem solving, supportive counselling, or learning and reinforcement of skills for coping with psychological distress or behavioural change. Instead, TAU uses generic attending skills as opposed to specific responding and questioning techniques. Case managers providing TAU will be trained with a standardised case management manual developed by CHAT based on the strength-based case management model.30 They will receive ongoing individual supervision with a senior case manager at CHAT to ensure treatment compliance.

Adverse event monitoring and attrition

Our trial has minimal known risks. Potential harms for both the SFBT and control groups include emotional discomfort during the intervention, which could rarely lead to increased symptom severity. To prevent and manage this risk, case managers will be trained in appropriate therapeutic interventions, suicide risk assessment and safety planning, and will receive regular supervision from a senior psychologist and psychiatrist. In cases of high suicidal risk, participants will be assessed by a psychiatrist who will follow IMH protocols for safety planning and appropriate referrals for care. All adverse events will be recorded and reported to the principal investigator, and to the Domain Specific Review Board (DSRB) within seven calendar days, and within 24 hours if they involve deaths and high suicide risk. In the case of significant clinical deterioration or adverse events (eg, self-harm, suicide or homicide), an interim analysis will be performed, and results will be presented to the principal investigator to determine the appropriateness of premature study termination. All participants will continue to receive TAU and modifications to the protocol will be submitted to the DSRB.

If participants are uncontactable, they will be considered to have dropped out. Follow-up text messages will be sent to monitor participants’ well-being, providing alternative treatment recommendations and resources, as well as an open invitation to continue receiving services at CHAT. Participants may be asked to withdraw from the study if adverse events occur (eg, high suicidal risk), or if they receive concomitant psychological or psychiatric services during the intervention period. Participants who drop out or withdraw from the study will be replaced if the recruitment numbers are not reached. Should any participants be physically harmed during the study, IMH will cover the medical expenses for injury treatment.

Outcomes and measures

All measures have been validated for use in non-Western and other Asian countries with culturally diverse populations, and are valid for use with adolescent and young adult populations.

Primary outcome

Psychological distress will be measured using the Kessler-10 (K-10),34 a 10-item screening scale for general psychological distress that has been validated in culturally diverse settings.35 36 Participants rate their experience of distress in the past 2 weeks, including fatigue, hopelessness, depression and worthlessness, on a five-point scale (1=none of the time to 5=all of the time). A higher summed score indicates greater severity. To determine treatment response in the intervention arm, a K-10 score of ≤19 will be considered a negative screen for psychological distress based on the measure’s recommended scoring.34 37

Secondary outcomes

Depressive symptoms will be measured by the Patient Health Questionnaire-9 (PHQ-9),38 a validated39 nine-item scale based on the Diagnostic and Statistical Manual for Mental Disorders, fifth edition (DSM-5)40 criteria for Major Depressive Disorder. Participants will rate the frequency of depressive symptoms experienced over the past 2 weeks on a four-point scale (0=not at all to 3=nearly every day). Higher summed scores indicate greater symptom severity.

Anxiety symptoms will be measured using the Generalised Anxiety Disorder-7 (GAD-7),41 a seven-item scale based on DSM-540 criteria for Generalised Anxiety Disorder, which has been validated in non-Western settings.42 Participants will rate the frequency of symptoms experienced over 2 weeks on a four-point scale (0=not at all to 3=nearly every day). Higher summed scores indicate greater symptom severity.

Functional impairment will be measured by the 12-item self-administered version of the WHO Disability Assessment Schedule 2.0 (WHODAS 2.0),43 which has been validated in community samples.44 This scale assesses clinical functioning over the past 30 days across the following domains: cognition, mobility, self-care, interpersonal interactions, life activities, and participation in society. Participants will rate items on a five-point scale of difficulty (0=no difficulty to 4=extreme difficulty/cannot do). Higher summed scores indicate greater functional impairment.

Clinically relevant proximal outcomes

Perceived self-efficacy will be measured using the 10-item General Self-Efficacy Scale,45 which has been validated in Asian countries.46 Respondents will rate their agreement with items, assessing the belief that one can perform novel or difficult tasks or cope with adversity, on a four-point scale (1=not at all true to 4=exactly true). Higher summed scores indicate higher levels of perceived self-efficacy.

Hopelessness will be measured by the Beck Hopelessness Scale-4,47 ,48 a four-item validated scale abbreviated from the original 20-item Beck Hopelessness Scale, which has been validated in East Asian populations.49 Participants will report their agreement with items assessing the affective, cognitive and motivational components of hopelessness on a four-point scale (0=not at all true to 3=often true). Higher summed scores indicate greater hopelessness.

Treatment satisfaction

Treatment satisfaction will be assessed using the Client Satisfaction Questionnaire,50 which has been validated in therapy settings,51 adapted to our interventions. It includes five items assessing service satisfaction on a four-point scale, and three open-ended questions regarding what participants found to be the most helpful, and their recommendations for improving the treatment services they received. Higher summed scores indicate greater satisfaction.

Assessment procedures

After treatment allocation, all participants in both arms will undergo four time points of assessment: baseline (T1), post-intervention (T2), 2 weeks post-intervention (T3), and 3 months post-intervention (T4). The window period of assessment is up to 2 weeks. For participants in the intervention arm, the T2 assessment is conducted when six SFBT sessions are completed, up to 8 weeks from T1 assessment. If a SFBT participant voluntarily withdraws from the study during the intervention period at any time, the participant will be invited to complete the T2 assessment and continue TAU with CHAT. The number of non-responders in the SFBT arm will be noted and will not be included in the 3-month post-intervention assessment, as this will allow us to assess if sustained clinical gains are due to SFBT and not the follow-up treatment. For the TAU group, T2 assessment is completed when a participant has been successfully referred to downstream services (eg, counselling, therapy or psychiatric services) or at 8 weeks from T1 assessment, whichever comes first.

Table 1 summarises the assessment schedule. Primary and secondary outcomes will be assessed at T1, T3 and T4. Outcomes will be measured 2 weeks post-intervention to prevent overlap with the intervention period as scales assess for symptoms experienced in the past 2 weeks. Clinically relevant proximal outcomes of hopelessness and self-efficacy will be measured at T1 and T2. Treatment satisfaction will be measured at T2. To monitor treatment engagement in both arms, case managers will record how sessions were delivered (whether in-person or remotely; via video or phone call), the frequency and duration of each session of interevention or phone contact, and each participant’s attendance.

Data management

Participants will complete English-language self-report questionnaires through an online survey on Qualtrics, an encrypted and medically compliant platform. Each assessment will take approximately 20 minutes to complete. Participants will be compensated SGD$25 for each assessment.

To ensure the confidentiality of the participants, all data collected (online supplemental appendix 2) will be deidentified and coded. Hardcopy data will be stored in locked cabinets, while electronic records will be maintained in encrypted and password-protected databases that do not contain identifying information. Identifiers will be stored in file systems separate from data files and be password protected. Project data will only be accessed by the project investigators, research coordinators, statisticians and the clinical team. Study data will be available for 6 years from the end of the study, until March 2031. All data from this study will reside with the IMH Office of Research, and will not be available for online access unless permission is granted by the IMH Institutional Review Board (IRB).

Statistical analysis

To test whether SFBT is efficacious in improving psychological distress (primary outcome), depressive and anxiety symptoms, and functional impairment (secondary outcomes) from baseline (T1) to 2 weeks post-intervention (T3) and whether gains are sustained at 3 months post-intervention (T4), a two (intervention: SFBT, TAU case management) by three (assessment time: T1, T3, T4) factorial analysis of variance (ANOVA) for repeated measures will be conducted. This will examine the statistical significance for the main effect of intervention and time, and the interaction between them. For binary outcomes (K-10 cut-off score of ≤19), a logistic generalised estimating equations analysis will be used for detecting the intervention effect. Significant main effects will be probed with multiple two-way comparison tests (ie, T1 vs T3, T1 vs T4, and T3 vs T4). To explore whether SFBT is associated with greater improvements than TAU in self-efficacy and hopelessness (proximal outcomes) and reductions in downstream referral rates from baseline to post-intervention (T2), ANOVA for repeated measures will be conducted for T1 versus T2. For all analyses, covariates will include clinical stage, age, sex, race, employment, marital status, educational level, and history of psychiatric treatment. Effect sizes (Cohen’s d) for each outcome will be calculated to indicate the magnitude of change in treatment outcomes for each treatment group from T1 to T3, T1 to T4, and T3 to T4. Established thresholds will be applied for interpreting the effect sizes, with Cohen’s d of 0.2 denoting a small effect, 0.5 a medium effect, 0.8 and above a large effect.52 Participants in each group will be analysed according to intention-to-treat principles. Missing data will be analysed using the last observation carried forward, a common method to handle missing data in intervention clinical trials most likely due to drop-outs or treatment disengagement, as it maintains sample size and allows for an intention-to-treat analysis. Sensitivity analyses will be conducted with multiple imputations for missing data.53 All statistical analyses will be performed in SPSS version 29 (IBM Corp, 2022).

Data monitoring

Our trial has a short duration, a modest sample size and minimal known risks. A formal data monitoring committee is not required by the IRB. Analysis will only be completed at the end of the intervention trial and after follow-up data has been collected. In the case of significant clinical deterioration or improvement, an interim analysis will be performed and results will be presented to the PI to determine the appropriateness of premature termination. To ensure data quality and the feasibility of the study, study team members will randomly audit 10% of available data semi-annually. This audit will inform any necessary changes in procedures. Discrepancies in data will be corrected and deviations from the protocol will be reported to the PI and the IRB.

Ethics and dissemination

The Clinical Research Committee (IMH) (reference 822–2022, 4 January 2023) and DSRB of the National Health Group in Singapore (reference 2023/00052, 24 August 2023) have provided ethical approval of the study. Research findings will be published in peer-reviewed scientific journals and disseminated to the community of mental healthcare system administrators and clinicians.

Data sharing statement

The data supporting the findings of this study is not publicly available due to privacy and ethical restrictions. However, deidentified data may be accessible from the last author, Dr Charmaine Tang, on reasonable request and with the approval of the IRB. Researchers wishing to access the data will be required to sign a data-sharing agreement to ensure compliance with privacy and ethical guidelines.

STRENGTHS AND LIMITATIONS

This randomised controlled trial will be the first to examine the efficacy of case manager delivered, six-session SFBT compared with routine case management for psychological distress and other mental health outcomes among young people in Singapore. The lack of blinding among clinicians and participants is an inevitable limitation in psychotherapy-based trials and there may be a participant response and social desirability bias. In addition, while it is not feasible and pragmatic to implement structured fidelity measurement due to resource constraints, we enhance intervention fidelity by manualising the content and delivery of SFBT and TAU using systematic clinical note documentation, and providing robust clinical supervision, monitoring and auditing to ensure the case manager’s compliance with these treatment modalities.

If this study can demonstrate SFBT’s efficacy for psychologically distressed young people seeking mental health treatment, it will encourage increasing capacity of low-intensity treatments that can be delivered by frontline mental health case managers in Singapore, thus improving access to evidence-based psychological interventions in the community.