Association of loneliness and social isolation with mental disorders among medical residents during the COVID-19 pandemic: A multi-center cross-sectional study

•A large multi-center study among medical residents during the COVID-19 pandemic•Chinese medical residents had high incidence of loneliness and social isolation•Considerable number of Chinese medical residents experienced mental disorders•Both loneliness and social isolation increased the risk of mental disorders Loneliness and social isolation usually increase the risk of mental disorders. However, this association among Chinese medical residents during the COVID-19 pandemic remains unclear. This study was conducted in September 2022; 1,338 medical residents from three hospitals in Northeastern China were included in the final analysis. The data were collected via online self-administered questionnaires. Adjusted odds ratios and 95% confidence intervals were determined for adjusting for potential confounders by binary logistic regression. Among the 1,338 participants, 12.93% (173), 9.94% (133), and 9.72% (130) had experienced major depression, major anxiety, and suicidal ideation, respectively. Further, 24.40% (327) and 44.50% (596) of the total participants had experienced loneliness and social isolation. Loneliness increased the risk of major depression, major anxiety, and suicidal ideation (all p