Theme: Epidemiology & Public Health Research Year: 2019
Background: Income disbursement has been temporally associated with intensified drug use and
related harms, but its implication in HCV risk is understudied. We examined short-term changes in
drug injection frequency before/after receiving a significant cheque and associations with social
determinants of HCV infection among people who inject drugs (PWID).
Methods: Data were drawn from the HEPCO cohort in Montreal, Canada (2011-2017; recruitment
criteria: age ≥18, past six-month drug injection; study eligibility: past-month illicit drug use, cheque
receipt). Three-monthly questionnaires captured sociodemographics and drug use, including
injection frequency in the two days before and after receiving a significant cheque in the past
month. Individual-level change in the number of injections before/after cheque receipt was assessed
using the paired-sample Sign test. A two-part hurdle model then assessed the relative odds
(likelihood) and rate (magnitude) of any increase in the number of injections (‘cheque effect’) with
respect to recent unstable housing, cocaine use, frequent injection (past-month), incarceration (past
3-months), and opioid agonist therapy (OAT; current). Analyses adjusted for sociodemographic
covariates including income level and source. Cluster-robust standard errors were obtained via a
sandwich estimator.
Results: Overall, 705 participants (at baseline: 82% male, 92% white, median age 40, 91% receive
income assistance) contributed 4787 eligible observations. Injection frequency was typically greater
after (vs. before) cheque receipt (median 3 vs. 0 injections; p<0.05). 40% of participants reported
more injections after cheque receipt, 3.2% reported fewer, and 57% no change. Past-month
frequent injection, cocaine use, and unstable housing were associated with greater likelihood and
magnitude of the cheque effect; OAT with a greater likelihood but lower magnitude; and recent
incarceration with a lower likelihood of the cheque effect (all p<0.05).
Conclusion: ‘Cheque effects’ are exacerbated among PWID with known HCV risk factors and may act
as a transient temporal link in the causal pathway to infection.
Disclosure of Interest Statement: JB receives advisor fees from Gilead Sciences and Merck and
holds a research grant from Gilead Sciences, outside of this current work. SBH, BJ, PB: no interests to
declare.