Association between Grit at the Start of Residency and Depressive Symptoms at the End of Residency Among Postgraduate Year 1 Medical Residents in Japan: A Longitudinal Study

Background Grit, defined as perseverance and passion for long-term goals, played an essential role in academic success and resilience in the medical profession. Previous cross-sectional studies indicated an association between higher grit and lower depressive symptoms among medical residents. However, no longitudinal studies examined whether grit was associated with later depressive symptoms during residency training. This study explored the association between grit at the start of a job and depressive symptoms at the end of the first-year postgraduate (PGY1) residency among Japanese medical residents. Methods This longitudinal study analyzed data from all first-year postgraduate residents at Tokyo Medical and Dental University in Tokyo, Japan, from 2021 to 2023. We administered surveys at the start of the first-year postgraduate residency and again at the end. We measured grit using the Japanese version of the Short Grit Scale (Grit-S) and assessed depressive symptoms with the Center for Epidemiologic Studies Depression Scale. We examined the association between grit at the baseline and depressive symptoms at the end of the first-year postgraduate residency using Poisson regression with robust error variance analysis. Results Of the 146 residents, 28 (19.2%) exhibited depressive symptoms at the end of first-year postgraduate residency. After adjusting for baseline depressive state, age, sex, graduated university, sleeping hours, and training program, a one-unit increase in Grit-S score was associated with a 42% lower risk of depressive symptoms at the end of the first-year postgraduate residency (relative risk [RR]: 0.58; 95% confidence interval [CI]: 0.37–0.88). Furthermore, the Grit-S subscales, perseverance of effort and consistency of interest, were all associated with a lower risk of depressive symptoms (RR: 0.68; 95% CI: 0.48–0.96, RR: 0.70; 95% CI: 0.49–0.99, respectively). Conclusion This study demonstrated that higher grit at the start of residency was significantly associated with a lower risk of depressive symptoms among Japanese medical residents by the end of their first postgraduate year.