Background. The purpose of this study was to assess the risk of sequential acquisition of anal human papillomavirus (HPV) infection following a type-specific genital HPV infection for the 9-valent vaccine HPV types and investigate factors associated with sequential infection among men who have sex with women (MSW).
Methods. Genital and anal specimens were available for 1348 MSW participants, and HPV genotypes were detected using the Roche Linear Array assay. Sequential risk of anal HPV infection was assessed using hazard ratios (HRs) among men with prior genital infection, compared with men with no prior genital infection, in individual HPV type and grouped HPV analyses.
Results. In individual analyses, men with prior HPV 16 genital infections had a significantly higher risk of subsequent anal HPV 16 infections (HR, 4.63; 95% confidence interval [CI], 1.41–15.23). In grouped analyses, a significantly higher risk of sequential type-specific anal HPV infections was observed for any of the 9 types (adjusted HR, 2.80; 95% CI, 1.32–5.99), high-risk types (adjusted HR, 2.65; 95% CI, 1.26, 5.55), and low-risk types (adjusted HR, 5.89; 95% CI, 1.29, 27.01).
Conclusions. MSW with prior genital HPV infections had a higher risk of a subsequent type-specific anal infection. The higher risk was not explained by sexual intercourse with female partners. Autoinoculation is a possible mechanism for the observed association.