Background: The association between unemployment and poor health outcomes is well documented. Significant debate exists as to whether unemployment causes ill health or whether those with poor health find it harder to obtain and maintain employment. Factory closure studies are well placed to comment on causation. The objective of this study was to investigate associations between involuntary job loss, mortality and serious illness.
Methods: An 8-year follow-up of workers from two meat-processing plants in the Hawkes Bay region of New Zealand. A cohort (n = 1945) made redundant in 1986 was compared with a cohort (n = 1767) from the neighbouring plant that remained open until 1994. Incidence rates for mortality, cancer registrations and admissions to public hospitals were derived from record linkage with routinely collected national data.
Results: Follow-up for the period 1986-1994 was 96% complete for both plants. Among the cohort made redundant in 1986, there was an increased risk of serious self-harm which led to hospitalization or death (adjusted for age, sex and ethnicity relative risk [RR] = 2.47; 95% CI: 1.04-5.89) compared to the employed cohort. The RR of admission to hospital with a mental health diagnosis was 1.17 (95% CI: 0.68-2.01). There were no other statistically significant findings.
Conclusions: This study has most of the features of an 'ideal' factory closure study, in that it achieved near-complete follow-up of a large workforce made redundant and a similar employed workforce for 8 years. We found that exposure to involuntary job loss increased the risk of mental distress leading to serious self-harm. No other association was found.