The joint effect of unemployment and cynical hostility on all-cause mortality: results from a prospective cohort study

BACKGROUND: It is hypothesised that hostility accentuates the association between stressful conditions and health. This study aims to test this hypothesis by analysing the joint effect of unemployment and hostility on all-cause mortality among men and women. METHODS: The population was 3677 men and 4138 women from the Danish workforce who participated in a survey in 2000. The joint exposure variable was defined as 1) employed, not hostile, 2) unemployed, not hostile, 3) hostile and employed, 4) unemployed and hostile. Outcome was defined as all-cause mortality between 2000 and 2014. Data was analysed with Cox proportional hazards models with age as the underlying time scale. The interaction between unemployment and hostility was studied using the synergy index. RESULTS: Compared to employed non-hostile men, men who were both hostile and unemployed were at markedly higher risk of premature death with a hazard ratio (HR) of 3.19 (95% CI 2.22–4.69). A similar picture was found for hostile and unemployed women, with a HR of 1.97 (95% CI 1.24–3.12). However, the mortality in men and women exposed to both did not exceed what was expected from the combination of their individual effects. Hence, we did not find that hostility enhances the association between unemployment and all-cause mortality. CONCLUSION: Men and women exposed to both unemployment and hostility were at markedly high risk of premature mortality. However, this study did not support the hypothesis that the deleterious health effect of the combination of unemployment and hostility exceeds their individual effects. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12889-019-6622-7) contains supplementary material, which is available to authorized users.