Acquisition of anal human papillomavirus (HPV) infection in women: the Hawaii HPV cohort study

Background. The majority of anal cancer is associated with human papillomavirus ( HPV) infection, yet little is known about women's risk of acquisition of anal HPV infection. Methods. Risk factors for the acquisition of anal HPV infection were examined in a longitudinal cohort study of 431 women, via repeated measurement of HPV DNA. Results. Seventy percent of women were positive for anal HPV infection at one or more clinic visits from baseline through a follow-up period that averaged 1.3 years. The incidence of a high-risk ( HR) infection was 19.5 ( 95% confidence interval [ CI], 16.0-23.6) per 1000 woman-months. The most common incident HR HPV types were HPV-53, -52 and -16. The presence of an HR anal HPV infection at baseline increased the risk of an incident anal infection by 65%. Baseline HR cervical HPV infection also predicted the acquisition of an HR anal HPV infection ( odds ratio, 1.81 [ 95% CI, 1.09-3.02]). Nonviral risk factors for acquisition of HR HPV infection included younger age, lower socioeconomic status, greater lifetime number of sexual partners, past use of hormones, and condom use. Conclusions. The results of this study suggest that women's risk of anal HPV infection is as common as their risk of cervical HPV infection.