COLPOSCOPY FOR THE DIAGNOSIS OF SQUAMOUS INTRAEPITHELIAL LESIONS - A METAANALYSIS

Objective: To quantify by meta-analysis the performance of colposcopy to set a standard against which new technologies can be compared. Data Sources: MEDLINE was searched for articles on colposcopy for diagnosi s of squamous intraepithelial lesions (SIL). The search selected artic les from 1960 to 1996 combining the key word ''colposcopy'' with key w ords ''diagnosis,'' ''positive predictive value,'' ''negative predicti ve value,'' ''likelihood ratio,'' and ''receiver operating characteris tic (ROC) curve.'' Methods of Study Selection: Articles were selected if the authors studied a population of patients with abnormal screenin g Papanicolaou smears and presented raw data showing for each cervical lesion type the number of patients judged positive and negative by co lposcopic impression versus the standard of colposcopic biopsy results . Nine of 86 studies met these criteria. Tabulation, Integration, and Results: Biopsies had been categorized as normal, atypia, cervical int raepithelial neoplasia (CIN) I, CIN II, CIN III, carcinoma in situ, an d invasive cancer; we recalculated performance measures using the Beth esda system. Overall sensitivity, specificity, likelihood ratios, ROC curves, and the corresponding areas under the curves were calculated. The average weighted sensitivity of diagnostic colposcopy for the thre shold normal compared with all cervix abnormalities (atypia, low-grade SIL, high-grade SIL, cancer) was 96% and the average weighted specifi city 48%. For the threshold normal cervix and low-grade SIL compared w ith high-grade SIL and cancer, average weighted sensitivity was 85% an d average weighted specificity 69%. Likelihood ratios generated small but important changes in probability for distinguishing normal cervix and low-grade SIL from high-grade SIL and cancer. Areas under the ROC curve were 0.80 for the threshold normal cervix compared with all abno rmalities and 0.82 for the threshold normal cervix and low-grade SIL c ompared with high-grade SIL and cancer. Conclusion: Colposcopy compare s favorably with other medical diagnostic tests in terms of sensitivit y, specificity, and area under the ROC curve. New diagnostic methods f or the cervix can be compared with colposcopy using these quantified v alues. (C) 1998 by The American College of Obstetricians and Gynecolog ists.