Symptoms of depression and all-cause mortality in farmers, a cohort study: the HUNT study, Norway

OBJECTIVES: To explore all-cause mortality and the association between symptoms of depression and all-cause mortality in farmers compared with other occupational groups, using a prospective cohort design. METHODS: We included adult participants with a known occupation from the second wave of the Nord-Trøndelag Health Study (Helseundersøkelsen i Nord-Trøndelag 2 (HUNT2) 1995–1997), Norway. Complete information on emigration and death from all causes was obtained from the National Registries. We used the depression subscale of the Hospital Anxiety and Depression Scale (HADS) to measure symptoms of depression. We compared farmers to 4 other occupational groups. Our baseline study population comprised 32 618 participants. Statistical analyses were performed using the Cox proportional hazards models. RESULTS: The estimated mortality risk in farmers was lower than in all other occupations combined, with a sex and age-adjusted HR (0.91, 95% CI 0.82 to 1.00). However, farmers had an 11% increased age-adjusted and sex-adjusted mortality risk compared with the highest ranked socioeconomic group (HR 1.11, 95% CI 0.98 to 1.25). In farmers, symptoms of depression were associated with a 13% increase in sex-adjusted and age-adjusted mortality risk (HR 1.13, 95% CI 0.88 to 1.45). Compared with other occupations this was the lowest HR, also after adjusting for education, marital status, long-lasting limiting somatic illness and lifestyle factors (HR 1.08, 95% CI 0.84 to 1.39). CONCLUSIONS: Farmers had lower all-cause mortality compared with the other occupational groups combined. Symptoms of depression were associated with an increased mortality risk in farmers, but the risk increase was smaller compared with the other occupational groups.