Saiki M.Loerbroks A.Li J.Mahidol University2025-11-242025-11-242025-12-01Postgraduate Medical Journal Vol.101 No.1202 (2025) , 1303-131000325473https://repository.li.mahidol.ac.th/handle/123456789/113212Objective A growing number of studies have reported that occupational psychosocial factors increase the risk of cardiovascular disease. Allostatic load (AL) is a main biological mechanism that explains the pathway from stress to disease. This study examined whether work-to-family conflict (WFC) and family-to-work conflict (FWC) at baseline would be associated with changes in the AL index (ALI) across four years. Methods We used the Midlife in Japan survey, Wave I, and the biomarker projects, Waves I and II. This study included 152 participants with paid jobs and variables of interest at baseline and target biomarkers at baseline and follow-up. We examined the four-year longitudinal changes in the ALI using two methods: comparing ALI scores at baseline and follow-up, named "Two ALI approach,"and creating one ALI score considering changes at baseline and follow-up, named "One ALI approach."Negative binomial regression analysis and generalized estimating equations were used for analyses. The results were reported by count ratios (CRs) and 95% confidence intervals (CIs). Results In the final model, our results demonstrated that WFC at baseline was significantly associated with increased ALI using the "Two ALI approach"(CR 1.15, 95% CIs: 1.03, 1.28) and "One ALI approach"(CR 1.15, 95% CIs: 1.01, 1.32), whereas FWC did not show statistical significance in both methods. Conclusions WFC was longitudinally associated with increased ALI. It is crucial to mitigate the effects of work-to-family conflict. Key messages What is already known on this topic? Previous studies have documented that occupational psychosocial factors adversely affect workers' cardiovascular health. However, the underlying mechanisms, particularly whether perceptions of work-family conflict influence biomarkers prior to disease onset, are poorly understood. What this study adds? This study found that work-to-family conflict at baseline was significantly associated with increased allostatic load index over 4 years. Family-to-work conflict at baseline was not associated with increased ALI in 4 years. How this study might affect research, practice, or policy? Companies and occupational health providers can use work-to-family conflict and ALI as screening tools to enhance employees' cardiovascular health. Interventions targeting the reduction of work-to-family conflict might improve workers' cardiovascular health.MedicineArticleSCOPUS10.1093/postmj/qgaf1012-s2.0-1050221429641469075640622330