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.