To the Editor: Compared with the Australian population, all-cause mortality rates among prisoners are four times greater among men, and eight times greater among women.1 Fatal drug overdoses and suicides comprise the overwhelming majority of deaths in post-release cohorts;2 hence, a large proportion of post-release deaths are preventable. However, the information necessary to determine appropriate public health responses to the issue of post-release mortality is largely absent, because there is no routine nationwide collection of numbers of prison separation episodes as there is, for example, for prison receptions.3

We aimed to estimate the number of inmate separation episodes occurring in Australia for the financial year 2007–08, using benchmark data obtained from public documents on the websites of each state and territory government department responsible for prisons. For each state and territory, we attempted to obtain the total number of inmates (ie, sentenced and on remand) released from prison for the financial year 2007–08. This figure was available for Victoria (5356), South Australia (4177) and the Northern Territory (2857). For New South Wales, data could only be obtained for separations of sentenced prisoners (7645). Hence, data on separations of either total or sentenced inmates were available for jurisdictions covering 62% of the national prison population.

To adjust for separations of prisoners on remand in NSW, we assumed that separations of sentenced prisoners comprised 40% of all separations, reflecting the ratios of sentenced to total separations in other jurisdictions. Hence, the total number of separations in NSW was estimated to be 19 113. A multiplier of 1.6 (1/0.62) was applied to the sum of separations from Victoria, SA, the NT and the adjusted figure for NSW separations, in order to estimate separations for the national prison population. This produced an estimate of 50 405 prison separations nationally for 2007–08. Each of these separations is associated with a significant increase in risk of death.

We have made an estimate of the number of prison separations in Australia for 2007–08, but believe that a more appropriate and precise method for obtaining this information would be to include separations for the total number of prisoners and for sentenced prisoners as items in routine data collection systems such as the Australia Bureau of Statistics Prisoners in Australia collection. This would enable better through-care service planning and provision of life-saving pre-release and post-release health services, such as prison-based opioid substitution treatment4 and overdose prevention and treatment interventions such as distribution of naloxone.5