A prospective study of alcohol consumption and HIV acquisition among injection drug users

Objective: To estimate the effect of alcohol consumption on HIV acquisition while appropriately accounting for confounding by time-varying risk factors. Design: African-American injection drug users in the AIDS Link to Intravenous Experience cohort study. Participants were recruited and followed with semiannual visits in Baltimore, Maryland between 1988 and 2008. Methods: Marginal structural models were used to estimate the effect of alcohol consumption on HIV acquisition. Results: At entry, 28% of 1525 participants were women with a median (quartiles) age of 37 (32-42) years and 10 (10-12) years of formal education. During follow-up, 155 participants acquired HIV and alcohol consumption was 24, 24, 26, 17, and 9% for 0, 1-5, 6-20, 21-50, and 51-140 drinks per week over the prior 2 years, respectively. In analyses accounting for sociodemographic factors, drug use, and sexual activity, hazard ratios for participants reporting 1-5, 6-20, 21-50, and 51-140 drinks per week in the prior 2 years compared to participants who reported 0 drinks per week were 1.09 (0.60-1.98), 1.18 (0.66-2.09), 1.66 (0.94-2.93), and 2.12 (1.15-3.90), respectively. A trend test indicated a dose-response relationship between alcohol consumption and HIV acquisition (P value for trend 9.7 x 10(-4)). Conclusion: A dose-response relationship between alcohol consumption and subsequent HIV acquisition is indicated, independent of measured known risk factors. (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins