Predictors of length of treatment, discharge reason, and re-admission to Aboriginal alcohol and other drug residential rehabilitation services in New South Wales, Australia

Introduction
Aboriginal clients accessing Aboriginal community-controlled residential alcohol and other drug rehabilitation services in New South Wales, Australia believe they have better outcomes due to culturally appropriate care. However, there is a paucity of published treatment outcome data. This study aims to identify predictors of treatment outcomes based on client characteristics at intake.

Methods
A cross-sectional, retrospective, observational study of 2326 admissions to six services between January 2011 and December 2016. The outcomes were: (i) leaving treatment early; (ii) self-discharge or house discharge (by staff); and (iii) re-admission within two years. The predictors examined were Aboriginal status, age, justice system referral and primary substance of concern. Competing risk and Poisson regression analyses were used to identify trends in the data.

Results
The mean age of clients was 33 years, and the majority (56%) stayed at least 6 weeks. Aboriginal clients whose primary substance of concern was stimulants were almost eight times more likely to re-admitted within 2 years than other clients (risk ratio 7.91; P < 0.001). Aboriginal clients who were also referred from justice were more likely to self-discharge (risk ratio 1.87; P < 0.001). Furthermore, Aboriginal clients who were aged older than 30 were less likely to have a re-admission (risk ratio 0.32; P ≤ 0.001).

Discussion and Conclusions
This study showed client characteristics that are predictive of harmful outcomes include age under 30, justice client, primary substance of use and their interactions. Future research could build on these results to aid ongoing development of residential rehabilitation programs for Aboriginal peoples.