Association between relative income and mental health in adults during the COVID-19 pandemic in Korea: Insights from a community health survey

People of lower socioeconomic status are much more likely to be vulnerable to COVID-19. This study aimed to compare the associations between mental health according to relative national and community income levels during the COVID-19 pandemic. Mental health inequalities according to income level during the COVID-19 pandemic were assessed using the Korea Community Health Survey before (2019) and after the COVID-19 pandemic (2021). Univariate analyses were used to calculate the perceived stress and depression rates according to the risk factor categories. A multivariate logistic regression analysis was performed to identify the association between two types of income levels (Korean or community) and perceived stress and depression. In addition, we investigated the effect of relative income levels by subgroup (gender and region) on perceived stress and the experience of depression. During COVID-19, although depression crude rates increased (from 6.24% to 7.2%), perceived stress crude rates remained similar. In addition, as for mental health inequality according to community income level, even after adjusting for each independent variable, perceived stress [Odds Ratio (OR): 1.31, 95% Confidence Interval (CI):1.31-1.32] and experience of depression (OR: 1.63, 95% CI: 1.62-1.63) increased as the income level decreased. The effect of relative income level on perceived stress rate was found to be more pronounced in urban areas than in rural areas in terms of community income levels. Contrarily, the effect of relative income level on the depression rate was found to be weaker. Our findings demonstrated that mental health inequalities based on income level were more likely to occur during the COVID-19 pandemic and that disparities in community income levels may better reflect mental health inequalities.