Accuracy of the Papanicolaou test in screening for and follow-up of cervical cytologic abnormalities: A systematic review

Purpose: To evaluate the accuracy of conventional and new methods of Papani colaou (Pap) testing when used to detect cervical cancer and its precursors . Data Sources: Systematic search of English-language literature through Octo ber 1999 using MEDLINE, EMBASE, other computerized databases, and hand sear ching. Study Selection: Ail studies that compared Pap testing (conventional method s, computer screening or rescreening, or monolayer cytology) with a concurr ent reference standard (histologic examination, colposcopy, or cytology). Data Extraction: Two reviewers independently reviewed selection criteria an d completed 2 x 2 tables for each study. Data Synthesis: 94 studies of the conventional Pap test and three studies o f monolayer cytology met inclusion criteria. No studies of computerized scr eening were included. Data were organized by cytologic and histologic thres holds used to define disease. For conventional Pap tests, estimates of sens itivity and specificity varied greatly in individual studies. Methodologic quality and frequency of histologic abnormalities also varied greatly betwe en studies. In the 12 studies with the least biased estimates, sensitivity ranged from 30% to 87% and specificity ranged from 86% to 100%. Conclusions: Insufficient high-quality data exist to estimate test operatin g characteristics of new cytologic methods for cervical screening. Future s tudies of these technologies should apply adequate reference standards. Mos t studies of the conventional Pap test are severely biased: The best estima tes suggest that it is only moderately accurate and does not achieve concur rently high sensitivity and specificity. Cost-effectiveness models of cervi cal cancer screening should use more conservative estimates of Pap test sen sitivity.