Background: Human immunodeficiency virus (HIV)-seropositive men who have sex with men (MSM) are at risk for anal intraepithelial neoplasia (AIN) and cancer. The goal of this study was to identify risk factors associated with high-grade AIN (AIN-2,3) in HIV-positive MSM, including the receipt of highly active antiretroviral therapy (HAART).
Methods: A cohort study involving 247 HIV-seropositive MSM receiving HAART or initiating HAART was followed up every 6 months for 3 years with human papillomavirus (HPV) testing and high-resolution anoscopy to identify predictors of AIN-2,3 by Cox regression analysis and period prevalence logistic regression.
Results: AIN-2,3 was observed during the study in 132 (53%) of 247 participants. The progression rate to AIN-2,3 from a lesser abnormality at baseline was 12.8 cases per 1000 person-months (95% confidence interval [CI], 9.8-16.5 cases per 1000 person-months). The risk of AIN-2,3 increased with age (odds ratio [OR], 3.09 [95% CI, 1.12-8.52] for men 40-49 years of age and 4.78 [95% CI, 1.29-17.73] for men >50 years of age, compared with men <40 years of age) and for men whose CD4+ cell counts were <50 cells/mm(3) before starting HAART (OR, 14.40 [95% CI, 1.45-143.58]). Men who had been receiving their current HAART regimen for >4 years had a marginally significant lower risk of AIN-2,3 after adjustment for HPV (OR, 0.28 [95% CI, 0.07-1.06]) compared with those treated for <4 years. Anal HPV type 16 (HPV16) or type 18 (HPV18) infections (OR, 14.18; [95% CI, 3.51-57.32]) and HPV16 and HPV18 co-infection (OR, 31.03 [ 95% CI, 5.68-169.60]) were strongly associated with progression to AIN-2,3.
Conclusion: HPV16 and HPV18 infections and a low nadir CD4+ cell count increase the risk of AIN-2,3. Receiving the same HAART regimen for >4 years may contribute some benefit against AIN-2,3.