Impacts of Depression Case and Subcase on All-Cause Mortality Among Older People in China: Are There Gender Differences?

Background: Depression cases and subcases have increased in older communities. It is unclear whether and to what extent they were associated with all-cause mortality in older people. Little is known about gender differences in the association. Methods: We examined a random sample of 6,124 participants aged ≥60 years across five provinces in China. They were interviewed using a standard method of the GMS-AGECAT to diagnose depression case and subcase and record sociodemographic and disease risk factors at baseline, and to follow up their vital status. We employed Cox regression models to determine all-cause mortality in relation to depression cases and subcases, with adjustment for important variables, including co-morbidities and social support. Results: Over the 10 years follow-up, 928 deaths occurred. Compared to those without depression, participants with depression subcase (n=196) and case (n=264) had increased risk of all-cause mortality; adjusted hazard ratios (HR) were 1.46 (95% CI 1.07-2.00) and 1.45 (1.10-1.91). The adjusted HRs in men were 1.15 (0.72-1.81) and 1.85 (1.22-2.81), and in women 1.87 (1.22-2.87) and 1.22 (0.83-1.77) respectively. In participants aged ≥65 years, the adjusted HRs were 1.12 (0.68-1.84) and 1.99 (1.28-3.10) in men, and 2.06 (1.32-2.24) and 1.41 (0.94-2.10) in women. Increased HR in depression subcases was higher in women than man (ratio of HRs was 1.84, p=0.034). Conclusions: Older people with subcase depression could have increased all-cause mortality to a similar extent to those with case depression. More attention should be paid to subcases of depression in women to tackle gender inequalities and improve survival. Funding Statement: The data collection of the two cohort studies were funded by the Royal Society of UK, the BUPA Foundation (Grants Nos. 45NOV06, and TBF-M09-05) and Alzheimer’s Research UK (Grant No. ART/PPG2007B/2). Declaration of Interests: Non declared. Adam Spira received honoraria from Springer Nature Switzerland AG for Guest Editing special issues of Current Sleep Medicine Reports. Ethics Approval Statement: Informed consent was obtained from each participant. If an individual was unable to provide informed consent due to disability or limited educational level, their next of kin or care givers were invited to provide assent for participation.Ethical approvals for the Anhui cohort study and the 4-province study were obtained from the Ethics Committees of University College London, and School of Health and Wellbeing at University of Wolverhampton, UK and the Research Ethics Committee of Anhui Medical University.