Testing for Human Papillomavirus Strains 16 and 18 Helps Predict the Presence of Anal High-Grade Squamous Intraepithelial Lesions

BACKGROUND: More than 90% of anal cancers are caused by human papillomavirus, and human papillomavirus strains 16 and 18 are the most oncogenic. Anal high-grade squamous intraepithelial lesions are cancer precursors. Treating these high-grade intraepithelial lesions likely reduces the risk of cancer, but cytology is an imperfect screening test. OBJECTIVE: The purpose of this study was to determine whether human papillomavirus 16 and/or 18 testing better predicts the presence of high-grade squamous intraepithelial lesions. DESIGN: In this retrospective study, 894 consecutive patients underwent anal dysplasia screening with digital anorectal examination, anal cytology, high-risk human papillomavirus testing, and high-resolution anoscopy with biopsy. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of each test and for a novel screening protocol. The absolute and relative risk of high-grade squamous intraepithelial lesions for all of the cytology/human papillomavirus combinations were also calculated. SETTINGS: The study was conducted at a single practice specializing in anal dysplasia. PATIENTS: Ninety-two percent of participants were men who have sex with men. Forty-four percent were HIV-positive individuals who were well controlled on antiretroviral therapy. The median age was 50 years. MAIN OUTCOME MEASURES: The presence of high-grade squamous intraepithelial lesions as a function of human papillomavirus and the cytology results were measured. RESULTS: High-risk human papillomavirus testing alone demonstrated better sensitivity (96% vs 89%; p = 0.03) and negative predictive value (99% vs 96%; p = 0.008) over cytology. Human papillomavirus 16/18 testing increased specificity (48% to 71%; p < 0.0001) and positive predictive value (24% to 37%; p = 0.003) over testing for all of the high-risk strains. For each cytology category, high-grade squamous intraepithelial lesions were more prevalent when human papillomavirus 16/18 was detected. Benign cytology with 16/18 had a 31-fold increased risk of high-grade squamous intraepithelial lesions. LIMITATIONS: This study was conducted in a single private practice specializing in anal dysplasia screening with a mostly male population, and results might not be generalizable. CONCLUSIONS: Testing of high-risk human papillomavirus strains 16/18 improves specificity and positive predictive value over cytology for anal dysplasia screening. Patients testing positive for strains 16/18 are at a high risk for high-grade squamous intraepithelial lesions and should undergo high-resolution anoscopy regardless of the cytology result. See Video Abstract at http://links.lww.com/DCR/A654.