Objectives: Describe the standardized mortality ratio (SMR) and its trend in adults who have served time in prison.
Design: A retrospective cohort study of 85,203 adults imprisoned in New South Wales (NSW), Australia, between 1 January 1988 and 31 December 2002.
Methods: We obtained information on deaths by record linkage with the Australian National Death Index (NDI). Mortality rates were estimated using the person-time method. SMRs were calculated using sex, age, and calendar-specific death rates from the NSW population. Time trends in SMRs were assessed using the test for linear trends.
Results: The median overall follow-up of the cohort was 7.7 years. We identified 5137 deaths (4714 men, 423 women) among the cohort of which the vast majority (4834, 94%) occurred following release from custody. All-cause SMR was 3.7 (95% CI: 3.6-3.8) in men and 7.8 (95% CI: 7.1-8.5) in women. SMRs were substantially raised for deaths due to mental and behavioural disorders (men: 13.2, 95% CI: 12.3-14.0; women: 62.8, 95% CI: 52.7-74.9) and drug-related deaths (men: 12.8, 95% CI: 12.2-13.5; women: 50.3, 95% CI: 43.7-57.8). The SMR for death by homicide was 10.2 (95% CI: 8.9-11.7) in men and 26.3 (95% CI: 17.8-39.0) in women. Aboriginal men were 4.8 times, and Aboriginal women 12.6 times, more likely to die than the general NSW population. Over the study period on average all-cause SMR decreased significantly in men (p = 0.003) and women (p = 0.05) largely due to the decline in SMRs for drug-related deaths and suicide.
Conclusion: In the largest study so far reported, mortality of male and female offenders was far greater than expected for all major causes, especially deaths caused by drug overdose. Despite some indication of a reduction in excess mortality in recent years, there remains an overwhelming need for enhanced responses to mental health and drug problems for people who have been in prison.