Comparative Effects of Acceptance and Commitment Therapy, Cognitive Behavioral Therapy, and Treatment-as-Usual on Depression and Its Related Psychosocial Issues Among People With Marital Crisis in China

Study site This study adopts a multicenter design and is carried out under the academic guidance of Universiti Sultan Zainal Abidin (UniSZA) of Terengganu, Malaysia. Ethical approval is first obtained from the UniSZA Human Research Ethics Committee (UHREC), based on the ethical guidelines of UniSZA and the Declaration of Helsinki, before any participant-related activities are initiated. After the UniSZA approval is obtained, ethical clearance is then obtained from the ethics committee of each participating clinical institution in China.

The study participants came from two psychiatric secondary and primary referral centers in Guangdong Province, China: Yunfu City Yuncheng District People's Hospital and Zhaoqing City Duanzhou District Shangyitang Comprehensive Clinic. Yunfu City Yuncheng District People's Hospital has about 1,000 registered psychiatric patients receiving treatment; About 800 registered psychiatric patients are receiving treatment at Zhaoqing City Duanzhou District Shangyitang Comprehensive Clinic. These two medical institutions accept referrals from psychiatric patients from Guangdong Province and a few nearby provinces such as Guangxi, Hunan, Hubei, Fujian, Jiangxi, and Hainan。 Sample size The sample size is calculated using G*Power version 3.1 for a mixed analysis of variance (ANOVA) with three between-subjects groups (ACT, CBT, TAU) and four within-subjects assessment time points (T0, T1, T2, T3), specifying a small-to-medium effect size for the group by time interaction of f = 0.25, a two-tailed alpha of 0.05, a power (1 minus beta) of 0.80, a correlation among repeated measures of 0.50, and a non-sphericity correction of 1. The choice of f = 0.25 is informed by the meta-analytic effect size estimates reported by Cuijpers et al. (2023) for adult CBT for depression and by Zhao et al. (2023) for adult ACT for depression, both of which report medium effect sizes for the between-group differences in depressive symptoms at post-intervention. Under these assumptions, the minimum required sample size is 36 participants per group, totaling 108 participants for the trial. To account for an anticipated attrition rate of approximately 10% across the four assessment time points, the planned recruited sample size is inflated to 40 participants per group, totaling 120 participants for the trial. The expected analyzable sample size at T3 is 108 participants.

The assumed attrition rate of approximately 10% is a cumulative estimate across the full follow-up period and is consistent with dropout rates reported in comparable trials of group psychotherapy for depression with follow-up of similar length. Because loss may accrue at each of the four measurement occasions rather than only once, this cumulative figure corresponds to an average per-occasion attrition of roughly 3%; the recruitment target of 40 participants per group is therefore retained as a conservative allowance. In addition, the analysis follows the intention-to-treat principle and uses all available observations, which further reduces the impact of intermittent missing data at individual time points.

Recruitment of subjects This study employs simple random sampling as the sampling method. All patients who are registered for outpatient psychiatric treatment at the two study sites and who have a documented diagnosis of depressive disorder are listed and assigned a computer-generated random number. The computer then generates a random sequence for the selection of potential study participants from this list. The selected individuals are subsequently screened by a trained research assistant during a face-to-face assessment. During the face-to-face screening, marital crisis status (DAS total score of 97 or below) and all other inclusion and exclusion criteria are assessed. Only those who meet all inclusion criteria and do not meet any exclusion criteria proceed to the informed consent process and enrollment.

The recruitment research assistant is independent of the intervention delivery, the outcome assessment, and the data analysis, and is unaware of the trial hypotheses. The recruitment research assistant holds a bachelor's degree in psychology or a related discipline and receives a two-week structured training prior to the commencement of recruitment, covering the eligibility criteria, the procedures of the trial protocol, the principles of informed consent, the safeguarding of participant confidentiality, and the management of distress that may arise during the screening process.