Workplace stress and prescription of antidepressant medications: a prospective study on a sample of Italian workers

The main aim of this study was to examine prospectively the relationship between antidepressant prescriptions (ADP), as a proxy of depressive symptoms, and work-related stress, measured according to the demand-control model. A cohort of 2,046 union workers who participated in a survey on working conditions and health in 1999-2000 was followed up to 2005, through the Regional Drug Prescription Register, for an ADP. The relative risks associated with demand, control and job strain were estimated using Poisson regression, adjusting for age, sex and other workplace factors (shift work, overtime, loud noise and psychological violence). In final multivariable models, high demand significantly increased the risk of depressive symptoms among blue collars (RR = 1.82), whereas among white collars, it was significantly protective (RR = 0.38). No significant relationship was found for job control or strain in either occupational class. The direct association observed elsewhere among blue collars between depressive symptoms and demand was confirmed, but not for job control or job strain. It cannot be ruled out that the association with demand was at least in part determined by reverse causation, due to exposure over-reporting among subjects with subclinical depressive symptoms at baseline. The protective effect of demand among white collars is not consistent with the literature and may be attributable to the particular characteristics of this sample, which included mainly workers employed in public administrative positions.