LAUSR

Adequate adherence to medications for hepatitis C infection (HCV) among people who inject drugs (PWID) is crucial for cure. However, active drug use may interfere with optimal adherence. Using data from the PREVAIL study that randomized three models of care with different levels of intensity-modified directly observed therapy (mDOT), groups therapy (GT), or standard individual therapy (SIT)-we examined whether more intensive care models such as mDOT or GT would also increase adherence among participants with active drug use compared to those without at baseline and during the entire treatment period. The daily adherence was measured using electronic blister packs available for analysis from N=147 participants. Drug use was ascertained by urine toxicology tests and defined in four ways: at baseline, and ever, frequent, and concurrent use during treatment period. Regardless of how drug use was defined, adherence of drug users was the greatest in mDOT, the lowest in SIT, and middle in GT. For instance, adjusted adherence was significantly higher for participants with baseline drug use than those without in mDOT (86.6±3.9(SE) vs. 76.8±4.3, p=.035) but significantly lower for those with baseline drug use in SIT (64.7±4.1 vs. 79.1±4.2, p=.003). Among non-drug users, there was no such clear dose-response relationship between intensity levels of care and adherence. In conclusion, more intensive care models should be implemented to promote adherence and mitigate the potential negative effect of drug use on adherence among PWID living with HCV.