OBJECTIVE: To evaluate the adequacy of cytology in detecting cervical intraepithelial neoplasia (CIN) among human immunodeficiency virus (HIV)-seropositive women compared to controls. METHODS: A cross-sectional study was carried out evaluating 241 HIV-seropositive women and 991 controls (404 HIV seronegative and 587 of unknown HIV status) at risk for CIN attending a vaginitis clinic. All patients had a Pap smear and a standard colposcopic examination of the lower genital tract. Cervical biopsies were taken as indicated by colposcopy. Cytology and histology slides were read by a cytopathologist blinded to patients' serostatus. False-negative cytologic cases were reviewed by three independent cytopathologists to estimate sampling and screening error rates. Sensitivity, specificity, and false-negative rate of cytologic smears were compared between HIV seropositives and controls. We estimated the sampling and screening error rates among cases with false-negative cytology. RESULTS: Among seropositives, the sensitivity, specificity, and the false-negative smear rate for CIN were 73.4% (47/64), 97.1% (134/138), and 26.6% (17/64), respectively. The corresponding figures in controls were 83.8% (83/99), 99.04% (825/833), and 16.2% (16/99), respectively, and did not differ significantly from those of seropositives. The negative predictive value of cytology was lower among seropositives (134/151) than in controls (825/841, chi2 = 34.8, P < .001). The agreement between cytologic readings and combined colposcopy and histology was stronger among controls (kappa = 0.789, 95% CI 0.723 to 0.856) than among seropositives (kappa = 0. 593, 95% CI 0.475 to 0.712). Three independent cytopathologists were unable to detect atypical cells in 52.9% (9/17) of false-negative smears taken from seropositive women as opposed to 37.5% (6/16) of controls. CONCLUSIONS: The sensitivity, specificity, and false negative rate of screening cytology for CIN among HIV seropositive women are comparable with those in the general population. Since almost 50% of false-negative results could be attributed to sampling errors, more frequent cytological screening may prove to be beneficial to this high-risk group.
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