The new finding counters the belief that HIV infected IDUs were less likely to benefit from HAART.
During the study, the researchers found little difference in the survival rate between IDUs and non-IDUs after 4-5 years of receiving the treatment.
Since the mid-1990s, significant reductions have been observed in illness and death related to the human immunodeficiency virus (HIV) among patients receiving HAART.
"However, a large number of prior reports have demonstrated that because of issues of social instability related to illicit drug addiction, HIV-infected IDUs may not be deriving the full benefits of HAART," wrote the authors.
For the study, the research team led by Dr. Julio S. G. Montaner of the University of British Columbia and St. Paul's Hospital, Vancouver compared the rate of death between 3,116 patients with and without a history of injection drug use initiating HAART in a HIV/AIDS treatment program in British Columbia, Canada.
Of the 3,116 patients, 915 were IDUs (29.4 percent).
Treatment with HAART was initiated between August 1996 and June 2006. The median (midpoint) duration of follow-up was 5.3 years for IDUs and 4.3 years for non-IDUs. Patients were followed up until June 30, 2007.
During the study period, 622 individuals died that included 232 IDUs and 390 non-IDUs.
Through seven years after the initiation of HAART, the researchers found that the cumulative all-cause mortality rate was not statistically different between the 915 and 2,201 non-IDUs.
Further analysis also showed similar rates of death for both groups, after adjustment for age, sex, baseline AIDS diagnosis, baseline CD4 cell count, adherence and physician experience.
"Although our findings cannot be generalized outside of [this] cohort, as efforts to improve use of HAART among IDUs expand, the fact that survival patterns were not significantly different between IDUs and non-IDUs should help to challenge the increasingly prevalent belief that IDUs may be markedly less likely to benefit from HAART," said the authors.
"Based on these results, we conclude that HAART regimens may have effectiveness at a populational level that is not significantly different regarding the survival of individuals with and without a history of injection drug use," they added.
The study appears in the journal JAMA.