Association between Grit and depressive symptoms at the timing of job start among medical residents during the COVID-19 pandemic in Japan: a cross-sectional study

Introduction The COVID-19 pandemic had an additional negative impact on the mental health of healthcare workers, including residents. Previous studies revealed that grit, which is an individual trait to achieve long-term goals unrelated to intelligence quotient, is not only positively associated with academic achievement and career success but also negatively correlated with depression. This study aimed to examine the association between grit and depressive symptoms among residents at the time of job start during the coronavirus disease 2019 (COVID-19) pandemic in Japan. Materials and methods This cross-sectional study used data from all post-graduate year 1 residents from March 2020 to April 2022 at Tokyo Medical and Dental University, Tokyo, Japan. Grit was measured by the Japanese version of Grit-S. The resident's depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. The association of interest was examined using logistic regression analysis. Results Among 221 residents, 28 (12.7%) have depressive symptoms. One unit increase in Grit-S score after adjusting for age, sex, graduated university, and sleeping hours was associated with lower odds of having depressive symptoms by 63% (odds ratio [OR]: 0.37; 95% confidence interval [CI]: 0.19-0.74). Further, the perseverance of effort subscale score was associated with lower odds of having depressive symptoms after covariate adjustment (OR: 0.43; 95% CI: 0.22-0.84). Conclusions Higher grit scores were associated with lower odds of having depressive symptoms among residents at the timing of job start during the COVID-19 pandemic. Regular mental health assessment is particularly important for residents with low grit scores at entry.