Agricultural activities and risk of treatment for depressive disorders among the entire French agricultural workforce: the TRACTOR project, a nationwide retrospective cohort study

Background: Although depression is a major issue among farming population, to date, there have been few studies on specific agricultural activities. We aimed to investigate whether, among the entire French farm manager (FM) workforce, certain agricultural activities are more strongly associated with depression than others. Methods: This nationwide retrospective cohort study used data from an administrative health database available to the TRACTOR project. This database pertains to the entire French agricultural workforce (overseas workers not included). Data were analyzed from January 2021 to December 2022. All FMs that worked at least once over the period 2002–2016 were included. The outcome measure was the association between 26 agricultural activities and the risk of depression measured as hazard ratios (HRs) after adjusting for age, sex, and pre-existing medical comorbidities. The time to first depression insurance declaration, or first antidepressant prescription claim was used as the underlying timescale. For each activity, the reference/control group included all FMs that never performed the considered activity between 2002 and 2016, while the exposed group included FMs that performed the considered activity at least once from 2002 to 2016. Four sensitivity analyses were conducted to test hypotheses, and to address potential sources of bias. Findings: There were 84,507 (7.76%; 28.2 cases per 1000 person-years) depression cases among 1,088,561 FMs (mean age 46.6 [SD 14.1]). Compared to other activities, dairy farming (HR = 1.37, 95% confidence interval: 1.32–1.42), cow farming (HR = 1.53 [1.47–1.59]), poultry and rabbit farming (HR = 1.37 [1.27–1.50]), and mixed farming (HR = 1.30 [1.24–1.36]) were more strongly associated with depression. Sex differences were observed, with most of the time, risks higher for females than for males. Interpretation: Agricultural activities at risk of depression among the entire French agricultural workforce were identified. These findings do represent a crucial first step on the road to implement effective preventive measures against depression to determine where additional resources should be allocated to screen for depression, along with intervention. Funding: MIAI@Grenoble Alpes, and Mutualité Sociale Agricole.