What drives the number of high-risk human papillomavirus types in the anal canal in HIV-positive men who have sex with men?

We estimated the effect of sexual behavior, age, and immunodeficiency on the number of high-risk human papillomavirus (HR-HPV) types in the anal canal among human immunodeficiency virus-positive men who have sex with men (MSM). Anal samples were genotyped with the Linear Array HPV Genotyping Test, and risk factors were investigated with Poisson regression. Of 586 MSM, 69% were Spanish, and 25.6% were Latin American; the median age was 34.9 years (interquartile range [IQR], 30.1-40.8). The median number of recent sex partners was 6 (IQR, 2-24 sex partners), and the median CD4(+) T-cell count was 531.5 cells/mm(3) (IQR, 403-701 cells/mm(3)). The prevalence of any and multiple HR-HPV infections was 83.4% and 60.5%, respectively. The most common types were HPV-16 (42%), HPV-51 (24%), HPV-39 (23.7%), and HPV-59 (23.5%). Age had a statistically significant, nonlinear association with the number of types, with the highest number detected around 35 years of age (P < .001). The number of recent sex partners had a statistically significant, fairly linear association on the log scale (P = .033). The high prevalence of HR-HPV types is associated with recent sexual behavior and age.