By Liz Highleyman

Injection drug users (IDUs) with HIV can benefit as much from antiretroviral therapy as non-users, according to a study presented Sunday, August 3, in advance of the XVII International AIDS Conference in Mexico City, and published in the August 6 Journal of the American Medical Association.

Julio Montaner from the University of British Columbia and colleagues noted as background that HAART has often been withheld from HIV positive IDUs due to assumptions that their unstable lifestyles may lead to inferior outcomes, for example because of poor adherence. Some prior reports have shown that IDUs are less likely to be prescribed HAART and that a history of injection drug use is a predictor of worse treatment outcomes. However, long-term evaluations of HIV treatment outcomes among IDUs compared with other transmission risk groups are lacking.

The present study compared survival rates among HIV positive individuals initiating HAART with and without a history of injection drug use. The investigators analyzed 3116 participants in a population-based, prospective cohort study in British Columbia known as HOMER (HAART Observational Medical Evaluation and Research). About 80% of cohort participants were men and the median age was about 39 years. Nearly one-third (29.4%; n = 915) were classified as IDUs, though the researchers did not assess the impact of past versus ongoing drug use.

Participants started HAART between August 1996 and June 2006, and were followed through the end of June 2007. The median duration of follow-up was 5.3 years for IDUs and 4.3 years for non-IDUs.

Results

Overall, 622 cohort participants (232 of 915 IDUs and 390 of 2201 non-IDUs) died during the follow-up period.

This represented a crude mortality rate of 20.0%.

7 years after HAART initiation, cumulative all-cause mortality rates were similar for IDUs and non-IDUs (26.5% vs 21.6%, respectively; P = 0.47).

In a multivariate Cox regression analysis adjusting for demographic and disease-related factors, mortality rates were similar for IDUs and non-IDUs (hazard ratio 1.09).

Based on these findings, the study authors concluded, "In this study population, injection drug use was not associated with decreased survival among HIV-infected patients initiating HAART."

"[T]he 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," they wrote.

They added that "[a]lthough subtle differences in survival" began to emerge by 84 months, 5-year survival was "virtually identical" in an analysis that excluded accidental causes of death.

They also noted that while this study only included participants on HAART, IDUs as a group are less likely to be on antiretroviral treatment, so in a comparison of all HIV positive IDUs -- treated and untreated together -- "it is likely that mortality rates would be higher among IDUs."

8/05/08

Sources

E Wood, RS Hogg, V Dias Lima and others. Highly active antiretroviral therapy and survival in HIV-infected injection drug users. Journal of the American Medical Association 300(5): 550-554. August 6, 2008.

Journal of the American Medical Association. Highly active antiretroviral therapy of similar benefit for HIV-infected injection drug users. Media release. July 30, 2008.