Abstract
BACKGROUND: Lifetime unemployment exposure increases in a cumulative way the risk of chronic diseases and premature death but the linearity of these relationships is still unclear. METHODS: The analyses were performed using individual data from 114,307 participants aged 18 to 75 years who were followed for 7 years after inclusion in the large population-based French cohort CONSTANCES. Unemployment exposure was measured as the total number of unemployed quarters accumulated during the lifetime and categorized into quartiles (low, average, high, very high exposure) along with the group of participants who were never exposed to unemployment. The associations of lifetime unemployment exposure with cardiovascular disease, cancer and all-cause mortality rates during follow-up were assessed by using logistic regression models adjusted for major confounding factors. Adjusted logistic regression models were also used to examine the associations between lifetime unemployment exposure and the prevalence of bad working conditions at inclusion. RESULTS: The associations of lifetime unemployment exposure with cardiovascular disease and all-cause mortality rates appear to be J-shaped with lower rates observed in participants with a low unemployment exposure compared to those never exposed (odds ratios (95% CI) of 0.78 (0.63-0.96) and 0.81 (0.60-0.97) respectively). In contrast, an increase in cardiovascular disease and all-cause mortality rates is observed in participants with a high (1.40 (1.17-1.67) and 1.50 (1.18-1.89) respectively) and even more a very high unemployment exposure (1.64 (1.42-1.89) and 2.09 (1.74-2.50) respectively). These J-shaped associations are no longer significant when adjusted for working conditions at inclusion. The prevalence of bad working conditions at inclusion is also reduced in participants with a low unemployment exposure compared to those never exposed (0.83 (0.79-0.86)) while it is increased in participants with a high (1.61 (1.55-1.68)) and even more a very high unemployment exposure (2.12 (2.04-2.21)). CONCLUSIONS: The non-linear relationships of lifetime unemployment exposure with cardiovascular disease and all-cause mortality rates may be related to the health benefits of having the occasional opportunity to leave jobs with bad working conditions over the life course.