Effect of modified income assistance payment schedules on substance use service access: Evidence from an experimental study

Background: Despite being critical to reducing the impacts of poverty internationally, synchronized monthly government income assistance payments are linked to intensified drug use and associated harms, including disrupted access to substance use-related services. This study evaluates whether alternative income assistance distribution schedules improve harm reduction (HR), pharmacotherapy and substance use service utilization. Methods: This exploratory, parallel group, unblinded, randomized controlled trial analyzed data from adults (n = 192) in Vancouver, Canada receiving income assistance, and reporting active, regular illicit drug use. Participants were randomly assigned on a 1:2:2 basis for six income assistance payment cycles to: (1) existing government schedules (control); (2) a "staggered" single monthly payment; or (3) "split & staggered" twice-monthly payments. Generalized linear mixed models analyzed secondary outcomes of HR, pharmacotherapy and substance use service utilization as well as barriers accessing these services. Results: Forty-five control, 71 staggered, and 76 split & staggered volunteers participated between 2015 and 2019. Multivariable modified per-protocol analyses demonstrate increased access to substance use services (Adjusted Odds Ratio [AOR] 1.64, 95% Confidence Interval [CI] 1.02-2.64) for split & staggered arm participants, and, conversely, increased barriers to HR for participants in the staggered (AOR 2.34, 95% CI 1.24-4.41) and split & staggered (AOR 2.16, 95% CI 1.08-4.35) arms. Results also showed decreased barriers to pharmacotherapy around government payments (AOR 0.23, 95% CI 0.06-0.90), pharmacotherapy around individual payments (AOR 0.12, 95% CI 0.02-0.58), and HR around individual payments (AOR 0.11, 95% CI 0.02-0.63) for staggered arm participants. Conclusion: Modifying payments schedules demonstrate improved access to overall substance use services, and reduced barriers to HR and pharmacotherapy around income assistance payments. However, increased overall barriers to HR access were also shown. These complex, predominantly beneficial findings support the exploration of offering alternative payment schedules to support service access.