Development and duration of human papillomavirus lesions, after initial infection

Background. To determine the potential value of human papillomavirus (HPV) vaccines, information concerning the incidence and duration of clinically important lesions is needed. Methods. A total of 603 female university students were followed for a mean duration of 38.8 months. Triannual gynecologic examinations included cervical and vulvovaginal specimen collection for Pap and HPV DNA testing. Women with cytologic evidence of a high-grade squamous intraepithelial lesion (SIL) were referred for colposcopically directed biopsy. Results. Among women with incident HPV infection, the 36-month cumulative incidence of cervical SILs found by cytologic testing (47.2%; 95% confidence interval [CI], 38.9%-56.4%) was higher than that of vaginal SILs (28.8%; 95% CI, 21.3%-38.2%). The median time to clearance of cervical and vaginal SILs was 5.5 and 4.7 months, respectively. Among women with incident HPV-16 or HPV-18 infection, the 36-month cumulative incidence of cervical intraepithelial neoplasia (CIN) grade 2 was 20.0% (95% CI, 10.8%-35.1%), and that of CIN grade 3 was 6.7% (95% CI, 2.5%-17.0%). The 36-month cumulative incidence of clinically ascertained genital warts among women with incident HPV-6 or HPV-11 infection was 64.2% (95% CI, 50.7%-77.4%). Conclusions. Intraepithelial lesions are common early events among women with incident HPV infection, and the interval between incident HPV-16 or HPV-18 infection and biopsy-confirmed CIN grade 2-3 appears to be relatively short.