Unemployment, mortality and the problem of health-related selection: Evidence from the Scottish Longitudinal Study

Summary: Objectives: Associations between unemployment and mortality are often complicated by processes of health-related selection. Testing whether unemployment causes health deterioration is complicated because failing health may increase the probability of unemployment. In some previous studies of unemployment and mortality a ‘wear-off’ period, after employment status is observed, is used which ignores the first few years of mortality events. It is assumed that selection effects will wear-off during this period. In
this study we aim to test the effectiveness of using wear-off periods.
Methods: Using data from the Scottish Longitudinal Study (SLS) we fitted logistic
regression models for the odds of death in a given time period after the 1991 census for those aged 35 – 64 in 1991. We compared the odds ratios for the labour force participation groups as well as comparing the changes in risk associated with cumulatively increasing the length of wear-off prior to follow-up.
Results: We found no evidence of health-related selection into unemployment.
Conclusion: We suggest that the use of the five year wear-off period in many studies of mortality and unemployment may be an ineffective and unnecessary technique for mitigating the effects of health-related selection.