Background:  To support ART among HIV⁺ injection drug users (IDU), comprehensive care programs have been established that include directly-observed treatment (DOT). We retrospectively reviewed the daily attendance and adherence records from 2 clinic programs in Vancouver, British Columbia, Canada, to determine therapeutic outcomes from these initiatives.

Methods:  We included 297 individuals who were receiving DOT between July 1998 and December 2004. Although changes in treatment strategies occurred during the time of observation, most were receiving once-daily observed therapy. Adherence was defined as the proportion of days receiving treatment when there were no planned treatment interruptions. The endpoint of interest was achievement of plasma viral load suppression defined as having at least 1 plasma viral load <500 copies/mL.

Results:  Median age was 41 years, 66% were male, 44% were of aboriginal ethnicity, and all participants were either current or recent IDU. The median pre-treatment CD4 was 180/mm³ (IQR 90 to 300), and the median plasma viral load was 45,900 copies/mL (IQR 2600 to 100,100). Of 297 patients, 61 (21%) died during the 78 months of follow-up. The overall adherence during the periods of observed therapy was 92%. Plasma viral load suppression was achieved by 245 (83%). In a Cox proportional hazards analyses, viral suppression was associated with male gender (RH 1.55, 95%CI 1.12 to 2.15), older age (RH per log₁₀ increase, 1.36, 95%CI 1.16 to 1.61), and lower baseline viral load (RH per log₁₀ increase, 0.81, 95%CI 0.72 to 0.89).

Conclusions:  Our results show that HIV programs that offer intensive supervision of ART can attract active IDU and also achieve a relatively high rate of adherence and plasma viral load suppression. Women, younger people, and those with higher baseline viral loads were less likely to attain viral suppression. Further analyses will evaluate determinants of sustained virologic response in this setting.