Impact of alternative income assistance disbursement on substance use disorder treatment adherence among people who use drugs

<i>Background:</i> The synchronized disbursement of income assistance payments is associated with increased drug-related harms and substance use disorder (SUD) treatment interruptions. Desynchronizing and splitting these payments can mitigate escalations in drug use, suggesting that downstream effects on SUD treatment may be impacted as well.<i>Objectives:</i> To understand the effect of desynchronizing and splitting income assistance payments on treatment patterns, including adherence to medications for opioid use disorder (MOUD).<i>Methods:</i> Data came from The Impact of Alternative Social Assistance on Drug Related Harm (TASA) study, conducted in Vancouver, Canada. This parallel arm, multi-group, randomized controlled trial assigned participants for six payment cycles to the synchronized monthly government schedule control or one of two intervention arms receiving payments desynchronized from the government schedule: a "staggered" group receiving monthly payments or a "split & staggered" group receiving semimonthly payments. Multivariable generalized estimating equations assessed the effect on overall SUD treatment adherence, MOUD adherence, and non-MOUD SUD treatment adherence.<i>Results:</i> Between October 2015 and January 2019, 194 participants were randomized and followed, including 89 (45.8%) women and 83 (42.8%) who self-identified as a person of color. In both intent-to-treat (ITT) and modified per-protocol (MPP) analyses, neither intervention arm was associated with decreased adherence to SUD treatment (ITT staggered arm adjusted odds ratio [AOR] 0.75, 95% confidence interval [CI] 0.36-1.55, split and staggered arm AOR 0.83, 95% CI 0.44-1.57; MPP staggered arm AOR 0.72, 95% CI 0.38-1.39, split and staggered arm AOR 0.89, 95% CI 0.54-1.46), including MOUD and non-MOUD.<i>Conclusions:</i> Alternative income assistance disbursement did not positively impact SUD treatment adherence, contrary to the hypothesis. Changing payment schedules also did not negatively impact SUD treatment adherence, suggesting that changes to payment delivery could be completed without impacting treatment.