Evaluating the effectiveness and cost–benefit of a worksite mental health program among manufacturing workers: A study protocol for a quasi-experimental study

Background: Mental health problems lead to the loss of about 12 billion workdays worldwide each year. This creates a major economic burden. In food manufacturing, workers often face various psychosocial stressors. These include high workload, time constraint, repetitive tasks, and low autonomy. These conditions can affect both mental health and work performance. Workplace mental health interventions have shown promising results in mental health improvement. However, most studies come from high-income countries and service sectors. There is still limited evidence from industrial settings in middle-income countries. To address this gap, a structured Worksite Mental Health Program (WMHP) was developed. Method: This study will employ a quasi-experimental two arm repeated measures design among workers from food manufacturing factories in Malaysia. The intervention group will receive an eight week WMHP including psychoeducation, mindfulness practices, progressive muscle relaxation, and breathing exercises. The comparison group will continue with routine workplace practices and receive a general mental health information pamphlet. Assessments will be carried out at baseline, one month post intervention, and at three months follow up. Primary outcomes include depression, anxiety, stress, and burnout. Secondary outcomes include job satisfaction, absenteeism, presenteeism, and economic outcomes. Changes over time will be analysed using Generalised Estimating Equations (GEE). A cost–benefit analysis (CBA) will also be conducted to assess economic impact. Anticipated results: The program is expected to improve mental health and work performance, while simultaneously reducing absenteeism and presenteeism. The economic evaluation is expected to demonstrate positive productivity gains associated with the program. Conclusion: This study will provide evidence on the effectiveness and economic value of a workplace mental health intervention in an industrial setting, informing workplace health strategies in Malaysia and similar contexts. Trial registration: Thai Clinical Trials Registry (TCTR): TCTR20241217003