The efficacy of 'modular dosage' in prison-based psychological interventions to reduce recidivism: A state-wide naturalistic study of convicted people in Australian prisons

Background: Criminal reoffending rates post-release from custody pose significant societal and economic challenges, with up to half of the world's released prisoners reoffending within two years. While psychological interventions based on the Risk-Needs-Responsivity model aim to address this issue, recent research highlights their inefficacy. The 'EQUIPS' suite of programs delivers innovative modular-style dosage to meet individual assessed needs and risk of offending, on a large scale in Australia. This study explores the impact of modular dosage in EQUIPS programs on reducing serious reoffending in the 12-months post-release. Methods: This study employs logistic regression to understand the dose-response relationship in 4345 participations who were referred to EQUIPS during their first incarceration episode (2015-2018). These analyses assess the effects of completing 0 vs. 1 program and 1 vs. 2 programs, addressing potential self-selection bias through inverse probability weighting. Results: Completing 1 vs. 0 program was associated with a 24 % decrease in serious reoffending within the first-year post-release. However, this effect was no longer observed in sensitivity analyses when including participants who did not complete treatment. Completing 2 vs. 1 program was not associated with additional reduction in recidivism. Conclusion: Increasing modular dosage of EQUIPS programs did not reduce recidivism in the 12-months post-release from custody, compared to a single program. The benefits of one compared to no programs were only observed when analyses were restricted to the 56 % of participants who completed all treatment sessions. Emphasising tailored treatment intensity and content, along with responsivity, may yield more meaningful reductions in recidivism.