Incidence and risk factors for mortality after release from prison in Australia: a prospective cohort study

Abstract

Aims: To estimate the incidence and identify risk factors for mortality in adults released from prisons in the state of Queensland, Australia.

Design: Prospective cohort study, linking baseline survey data with a national death register.

Setting: Selected prisons within Queensland, Australia.

Participants: Adults (n = 1320) recruited in Queensland prisons within 6 weeks of expected release, between August 2008 and July 2010, followed for up to 4.7 years in the community.

Measurements: Participants completed a comprehensive baseline survey covering psychosocial circumstances, physical and mental health, substance use and health risk behaviours. Clinical data were abstracted from prison medical records and obtained through probabilistic linkage with state-based, community health records. Dates of prison release and reincarceration were obtained from correctional records. Deaths were identified through probabilistic linkage with the National Death Index. Adjusted hazard ratios (AHR) were calculated using proportional hazards regression models. Standardized mortality ratios (SMR) were calculated using the population of Queensland as the reference. General population data were obtained from the Australian Bureau of Statistics.

Findings: The rate of mortality in the cohort was higher than in the age- and sex-matched general population of Queensland for all causes [SMR = 4.0, 95% confidence interval (CI) = 2.9-5.4] and drug-related causes (SMR = 32, 95% CI = 19-55). In a multivariable model, adjusting for age, sex and Indigenous status, factors associated with increased mortality risk included expecting to have average or better funds available on release (AHR = 2.9, 99% CI = 1.2-7.1), poor mental health (AHR = 2.6, 99% CI = 1.1-6.1) and self-reported life-time history of overdose (AHR = 2.5, 99% CI = 1.04-6.2).

Conclusions: People released from prison in Queensland, Australia are at increased risk of death, due particularly to drug-related causes. Those at greatest risk of death are characterized by poor physical and mental health and a history of risky substance use.

Keywords: Data linkage; mental disorders; mortality; prisoners; prospective studies; substance use disorders.