The effect of history of injection drug use and alcoholism on HIV disease progression.

The effectiveness of highly active antiretroviral therapy (HAART) in preventing disease progression can be negatively influenced by the high prevalence of substance use among patients. Here, we quantify the effect of history of injection drug use and alcoholism on virologic and immunologic response to HAART. Clinical and survey data, collected at the start of HAART and at the interview date, were based on the study Longitudinal Investigations into Supportive and Ancillary Health Services (LISA) in British Columbia, Canada. Substance use was a three-level categorical variable, combining information on history of alcohol dependence and of injection drug use, defined as: no history of alcohol and injection drug use; history of alcohol or injection drug use; and history of both alcohol and injection drug use. Virologic response (pVL) was defined by ≥ 2 log10 copy/mL drop in a viral load. Immunologic response was defined as an increase in CD4 cell count percent of ≥ 100%. We used cumulative logit modeling for ordinal responses to address our objective. Of the 537 HIV-infected patients, 112 (21%) were characterized as having a history of both alcohol and injection drug use, 173 (32%) were nonadherent (<95%), 196 (36%) had a CD4⁺/pVL⁺ (Best) response, 180 (34%) a CD4⁺/pVL⁻ or a CD4⁻ /pVL⁺ (Incomplete) response, and 161 (30%) a CD4⁻ /pVL⁻ (Worst) response. For individuals with history of both alcohol and injection drug use, the estimated probability of non-adherence was 0.61, and (0.15, 0.25, 0.60) of Best, Incomplete and Worse responses, respectively. Screening and detection of substance dependence will identify individuals at high-risk for nonadherence and ideally prevent their HIV disease from progressing to advanced stages where HIV disease can become difficult to manage.