Abstract
BACKGROUND: Depression and anxiety are the most common mental health issues experienced by workers. Although organizational intervention has been extensively evaluated as a primary prevention of depression and anxiety, the corresponding scientific evidence remains limited because of the lack of cluster randomized controlled trials (cRCT) and failure to detect organizational-level effects. Therefore, the present study aims to assess the preventive effects of four types of interventions on depression and anxiety among workers in an open, five-arm, parallel-group cRCT. METHODS: Overall, 140 worksites and 18,200 nested employees will be recruited from September 2023. The eligible worksites will be randomly assigned to each of the five arms, and programs will be offered for 6-12 months. The five arms are 1) psychoeducation for workers, 2) psychoeducation for supervisors, 3) work environment improvement, 4) physical activity promotion, and 5) active control. The primary outcomes of interest are depression and anxiety. We will also assess psychosocial factors at work, work engagement, health-related quality of life, well-being, economic outcomes, physiological outcomes of health checkups, cortisol levels extracted from fingernails, and indices representing the process and implementation outcomes, including program completion rates. Follow-up surveys will be conducted at 6, 12, and 18 months from baseline, and the primary endpoint is set at the 6-month follow-up. Repeated-measures multi-level mixed modeling will be used to evaluate the effect of each intervention compared with the control. ETHICS AND DISSEMINATION: The study protocol was approved by the Research Ethics Committee of the Kitasato University Medical Ethics Organization (C22-082). The results and findings of this study will be published in a scientific journal and disseminated to companies that participate in the study. TRIAL REGISTRATION NUMBER: UMIN000050949.