Abstract
BACKGROUND: The challenges of global aging would boost more workforce participation of older adults, and depression rate was increasing among older adults. This study aimed to explore the associations of workforce participation with depression among US older adults. METHODS: This cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) 2005-2018. Depression was measured with Patient Health Questionnaire-9 items (PHQ-9). Workforce participation was measured with work status, work types, shift work, and hours worked per week. Multivariate generalised linear and logistic regression models, also with restricted cubic spline (RCS) were performed to examine linear or non-linear associations between workforce participation and depression. Analyses of subgroup and sensitivity were conducted: using data from non-multiple imputation, participants aged over 65, and all non-excluded participants aged 60 or above to execute repeated analysis; recruiting propensity score matching (PSM) method that focused on selected SDoH, lifestyle, and health status-related factors to strengthen essential comaparability between workers and non-workers; employing two-stage least squares (2SLS) model and setting retirement age (over 65 years or not) as an instrumental variable (IV) to solve the potential reverse causation between work status and depression. RESULTS: A total of 10,312 participants aged 60 or above were enrolled with a prevalence of depression of 6.4%. There was a significantly negative association of PHQ-9 score with working (Exp [β] = 0.68; 95%CI: 0.53-0.87), working as private employee (Exp [β] = 0.67; 95%CI: 0.50-0.89), or working on regular daytime (Exp [β] = 0.65; 95%CI: 0.52-0.82). Especially, regular daytime working reduced depression risk by 52% compared with those who not working (OR = 0.48; 95%CI: 0.27-0.87). A significant decreased PHQ-9 score and depression risk as hours worked per week increased until reaching 34.86 and 25.35 in the RCS for generalised linear and logistic regression models, respectively. These effects were consistent across the analyses of subgroup and sensitivity. CONCLUSIONS: Regular daytime working was positively related to decreased depression risk among US older adults, and the suggested optimal working hours were 25 to 35 per week. Policymakers should appreciate the potential value of moderate workforce participation to mental health among older adults.