Bidirectional association between physical multimorbidity and subclinical depression in Chinese older adults: Findings from a prospective cohort study

Background: Both physical multimorbidity and subclinical depression pose a significant threat to aging population worldwide. The association between these conditions appeared to be in a bidirectional way, however the joint causal relationship yet to be fully understood in elderly Chinese population. Methods: A total of 4605 Chinese elders from the China Health and Retirement Longitudinal Study (CHARLS, 2011-2015) were included for the present study. Physical multimorbidity was defined as having two or more self-reported chronic physical conditions. Subclinical depression was defined by >= 12 scores assessed using the 10-item Centre for Epidemiological Studies Depression Scale. The bidirectional association between physical multimorbidity and subclinical depression was examined using multivariable logistic regression models, adjusting for covariates. Results: During study period, 23.99% of participant reported incident episode of subclinical depression and 21.36% reported physical multimorbidity. In fully adjusted model, those with physical multimorbidity were two times more likely to have subclinical depression (OR = 2.05, 95% CI: 1.71-2.46). Besides that, subclinical depression was associated with physical multimorbidity (OR = 1.84, 95% CI: 1.50-2.46), but in slightly less magnitude. Furthermore, the bidirectional association remains statistically significant across different subgroups. Limitations: Chronic conditions were all self-reported and we couldn't adjust for all confounders, which may be subject to measurement error. Conclusions: Physical multimorbidity and subclinical depression was associated in a bidirectional way in elderly Chinese population, which highlights the necessary of covering a broad spectrum of aspects of clinical management among adults with physical multimorbidity or subclinical depression.