Comparison of Workplace Social Capital between the Pre- and Post-Restriction Eras of Physician Working Hours: A Nationwide Repeated Cross-Sectional Study.

Introduction: Workplace social capital (WSC), defined as the features of social organization that promote coordination and cooperation for mutual benefit, is a relevant construct that contributes positively to employee and organizational wellness, and has recently attracted wide attention. However, factors associated with WSC in the field of medical education have not been investigated, including regarding the effect of physician working hour restrictions. Thus, the aim of the study was to investigate differences in the WSC of resident physicians before and after the April 2024 introduction of restrictions on physician working hours in Japan. Methods: We conducted a nationwide repeated cross-sectional survey in 25 hospitals across Japan. Pre- and post-restriction data were obtained in July and August 2022 and in December 2024, respectively. We evaluated WSC using the Japanese medical resident version of the WSC Scale, which comprises horizontal trust (i.e., trust in co-workers) and vertical trust (i.e., trust in supervisors) subscales. We used the total score and its domain scores, all of which range from 1 to 5, with higher scores indicating greater WSC, as outcome variables. We created a dummy variable (1 = post-restriction data [December 2024], 0 = pre-restriction data [July-August 2022]) and used it as the explanatory variable. We used a linear mixed-effects model to adjust clustering within hospitals and individual covariates. Results: We analyzed data for 428 respondents (pre-restriction, 246; post-restriction, 182 participants; man, 272). After adjusting possible confounders and clustering within hospitals, physician working hour restrictions were significantly associated with greater vertical trust (adjusted mean difference, 0.17; 95% confidence interval, 0.02 to 0.32). No clear trend was observed in the association among restrictions, total WSC score (adjusted mean difference, 0.13; 95% confidence interval, -0.01 to 0.26), and horizontal trust score (adjusted mean difference, 0.10; 95% confidence interval, -0.05 to 0.24). Conclusions: This nationwide multicenter study revealed significant vertical trust score differences between pre- and post-physician working hour restrictions. The implementation of physician working hour restrictions has improved vertical trust. These findings contribute to the literature on potential benefits of working hour restrictions on the organization of physician life and enhancement of patient care quality.