Prevalence and Risk Factors for Anal Squamous Intraepithelial Lesions in Women

BACKGROUND: Anal cancers are thought to arise from squamous intraepithelial lesions in the anal canal, and women infected with human immunodeficiency virus-1 (HIV) may be at higher risk of anal cancer. Our aim was to determine the prevalence of human papillomavirus (HPV)-related abnormalities of the anal canal in women and to characterize risk factors for these lesions. METHODS: We evaluated HPV-related abnormalities in 251 HIV-positive and in 68 HIV-negative women. We completed physical examinations and obtained questionnaire data on medical history and relevant sexual practices. Univariate and adjusted relative risks (RRs) and 95% confidence intervals (CIs) were computed using the Mantel-Haenszel procedure and regression techniques. All statistical tests were two-sided. RESULTS: Abnormal anal cytology, including atypical squamous cells of undetermined significance, low-grade squamous intraepithelial lesions, or high-grade squamous intraepithelial lesions (HSILs), was diagnosed in 26% of HIV-positive and in 8% of HIV-negative women. HSILs were detected by histology or cytology in 6% of HIV-positive and in 2% of HIV-negative women. HIV-positive women showed increased risk of anal disease as the CD4 count decreased (P<.0001) and as the plasma HIV RNA viral load increased (P =.02). HIV-positive women with abnormal cervical cytology had an increased risk of abnormal anal cytology at the same visit (RR = 2.2; 95% CI = 1.4 to 3.3). Abnormal anal cytology in HIV-positive women was associated with anal HPV RNA detected by the polymerase chain reaction and by a nonamplification-based test (RR = 4.3; 95% CI = 1.6 to 11). In a multivariate analysis, the history of anal intercourse and concurrent abnormal cervical cytology also were statistically significantly (P =.05) associated with abnormal anal cytology. CONCLUSIONS: HIV-positive women had a higher risk of abnormal anal cytology than did HIV-negative women with high-risk lifestyle factors. These data provide strong support for anoscopic and histologic assessment and careful follow-up of women with abnormal anal lesions.