Trends in the frequency and predictive value of reporting high grade abnormalities in cervical smears

BACKGROUND. The "organized approach" to cervical screening in Australia inc ludes standardized quality assurance measures for laboratories. This study examines changes in the frequency and the positive predictive value of repo rting severe abnormalities in cervical smears over a 3-year period as a gui de to the effects of implementing these measures. METHODS. The results of screening in 6-month periods from January 1995 to D ecember 1997 were determined. Biopsy follow-up for results in the high grad e epithelial abnormality ("HGEA") and "inconclusive: possible HGEA" categor ies was obtained from the Western Australian Cervical Cytology Registry (CC R). RESULTS, Approximately 40,000 smears were examined in each 6-month period. The frequencies of reporting HGEA were 0.47%, 0.59%, 0.79%, 0.85%, and 0.84 %, and 0.91% for the study periods (P < 0.001). For the inconclusive catego ry, they were 0.24%, 0.18%, 0.24%, 0.31%, 0.38%, and 0.35% (P < 0.001). Bio psy follow-up was available for 83.9%, 80.5%, 89.9%, 92.4%, 93.1%, and 90.3 % of the HGEA results and for 78.6%, 71.7%, 80.5%, 75.0%, 87.1%, and 85.9% of the inconclusive results over the study periods. The yield of high grade lesions for the biopsied cases was 82.6%, 82.3%, 83.1%, 79.5%, 80.9%, and 79% for HGEA cases and 58.2%, 41.9%, 60.6%, 52.8%, 47.5%, and 54.1% for inc onclusive cases. CONCLUSIONS. There was a doubling in the reporting of HGEA results, whereas the positive predictive value for biopsied cases remained at about 80%. Re porting rates for inconclusive: possible HGEA cases also doubled, but the y ield of biopsy-proven, high grade lesions remained at about 50%. These chan ges occurred in the absence of ancillary testing and with targeted rescreen ing methods. A high rate of reporting HGEA, in combination with a high posi tive predictive value, is among the most important indicators of cervical c ytology laboratory performance. Large improvements in results may occur usi ng conventional methods of quality assurance. Cancer (Cancer Cytopathol) 20 00;90:215-21. (C) 2000 American Cancer Society.