persistent depression. However, this study had limited statistical power and did not account for a number of relevant covariates [17]. Another investigation based on the entire GAZEL cohort study sample suggested the existence of a socioeconomic gradient with regard to depression trajectories, and particularly persistent symptoms. However, this study did not account for factors that can influence depression course over time [20]. The present analysis addresses the concerns risen by these two prior studies, by examining the relationship between occupational grade and depression course in 3,368 GAZEL study participants followed prospectively over up to 12 years, and controlling for factors potentially associated with occupational grade and depression measured at baseline and during follow-up (demographic characteristics including retirement status, social networks, negative life events, health behaviors, chronic illnesses including prior depression, Use of antidepressants).
AbstractObjectives: We tested the hypothesis that depression course varies with individuals' socioeconomic position, as measured by occupational grade.Methods: Study participants (n=3,368) belong to the French GAZEL cohort study. Depressive symptoms were measured using the Center for Epidemiological Studies-Depression (CES-D) scale in 1996, 1999, 2002, 2005 and 2008. We studied the course of depressive symptoms in participants with a baseline CES-D score above a clinically significant cut-off in 1996. Socioeconomic position was measured by occupational grade. Analyses were controlled for demographic factors (sex and age), as well as covariates potentially associated with depression course which were measured both at study baseline and during follow-up: retirement status, social network, tobacco smoking, heavy alcohol use, body mass, prior depression, somatic chronic disease, life events and use of antidepressants. Data were analyzed in a repeated measures logistic regression framework (Generalized Estimating Equations, GEE).
Results
Conclusions:Occupational grade predicts the course of depressive symptoms, which should be brought to the attention of policymakers and mental health specialists.