Impact of Harm Reduction Treatment with or without Pharmacotherapy on Polysubstance Use among People Experiencing Homelessness and Alcohol Use Disorder

Abstract

Objectives A prior randomized controlled trial showed behavioral harm reduction treatment for alcohol use disorder (AUD), or HaRT-A, was effective in improving alcohol outcomes and quality of life for people experiencing homelessness and AUD when provided with or without pharmacotherapy (ie, extended-release naltrexone). Because nearly 80% of the sample also reported baseline polysubstance use, this secondary study tested whether HaRT-A also positively impacted other substance use. Methods In the parent study, 308 adults with AUD and homelessness were randomized to receive HaRT-A plus intramuscular injections of 380-mg extended-release naltrexone (HaRT-A + extended-release naltrexone), HaRT-A plus placebo (HaRT-A + placebo), HaRT-A alone, or community-based services as usual (control). In this secondary study, we used random intercept models to detect changes in other substance use after exposure to any of the HaRT-A conditions. For less prevalent behaviors, outcomes included past-month use (cocaine, amphetamines/methamphetamines, opioids). For more prevalent behaviors (polysubstance, cannabis), outcomes were past-month use frequency. Results Compared with controls, participants who received HaRT-A showed significantly reduced 30-day frequency of cannabis use (incident rate ratio = 0.59, 95% CI = 0.40–0.86, P = 0.006) and polysubstance use (incident rate ratio = 0.65, 95% CI = 0.43–0.98, P = 0.040). No other significant changes were detected. Conclusions Compared with services as usual, HaRT-A is associated with reduced cannabis and polysubstance use frequency. The benefits of HaRT-A may thus extend beyond its impact on alcohol and quality of life outcomes to positively reshape overall substance use patterns. A randomized controlled trial is needed to further investigate the efficacy of such combined pharmacobehavioral harm reduction treatment for polysubstance use.