Does long-term experience of nonstandard employment increase the incidence of depression in the elderly?

Objectives: Our prospective study aimed toelucidate the effect of long-term experience of nonstandardemployment status on the incidence of depressionin elderly population using the Korean Longitudinal Studyof Ageing (KLoSA) study. Methods: This study used thefirst- to fourth-wave cohorts of KLoSA. After the exclusionof the unemployed and participants who experienceda change in employment status during the followupperiods, we analyzed a total of 1,817 participants.Employment contracts were assessed by self-reportedquestions: standard or nonstandard employment. Theshort form of the Center for Epidemiologic Studies DepressionScale (CES-D) served as the outcome measure.Hazard ratios (HRs) with 95% confidence intervals(CIs ) were calculated using Cox proportional hazardsmodels to evaluate the association between standard/nonstandard employees and development of depression.Results: The mean age of the participants was 53.90 (±7.21) years. We observed that nonstandard employmentsignificantly increased the risk of depression. Comparedwith standard employees, nonstandard employees had a1.5-fold elevated risk for depression after adjusting forage, gender, CES-D score at baseline, household income,occupation category, current marital status, numberof living siblings, perceived health status, and chronicdiseases [HR=1.461, 95% CI=(1.184, 1.805)]. Moreover,regardless of other individual characteristics, the elevatedrisk of depression was observed among all kindsof nonstandard workers, such as temporary and dayworkers, full-time and part-time workers, and directly employedand dispatched labor. Conclusions: The 6-yearfollow-up study revealed that long-term experience ofnonstandard employment status increased the risk of depressionin elderly population in Korea.