Background: Anal cancers are thought to arise from squamous intraepithelial
lesions in the anal canal, and women infected with human immunodeficiency
virus-1 (HIV) mag be at higher risk of anal cancer. Our aim was to determin
e the prevalence of human papillomavirus (HPV)-related abnormalities of the
anal canal in women and to characterize risk factors for these lesions, Me
thods: We evaluated HPV-related abnormalities in 251 HIV-positive and in 68
HIV-negative women. We completed physical examinations and obtained questi
onnaire data on medical history and relevant sexual practices. Univariate a
nd adjusted relative risks (RRs) and 95% confidence intervals (CIs) were co
mputed using the Mantel-Haenszel procedure and regression techniques, All s
tatistical tests were two-sided, Results: Abnormal anal cytology, including
atypical squamous cells of undetermined significance, low-grade squamous i
ntraepithelial lesions, or high-grade squamous intraepithelial lesions (HSI
Ls), 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 d
isease as the CD4 count decreased (P < .0001) and as the plasma HIV RNA vir
al load increased (P =.02), HIV-positive women with abnormal cervical cytol
ogy 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 wa
s associated with anal HPV RNA detected by the polymerase chain reaction an
d by a non-amplification-based test (RR = 4.3; 95% CI = 1.6 to 11), In a mu
ltivariate analysis, the history of anal intercourse and concurrent abnorma
l cervical cytology also were statistically significantly (P =.05) associat
ed with abnormal anal cytology. Conclusions: HIV-positive women had a highe
r risk of abnormal anal cytology than did HIV-negative women with high-risk
lifestyle factors. These data provide strong support for anoscopic and his
tologic assessment and careful followup of women with abnormal anal lesions
.