The "organized approach" to cervical screening in Australia includes standardized quality assurance measures for laboratories. This study examines changes in the frequency and the positive predictive value of reporting severe abnormalities in cervical smears over a 3-year period as a guide to the effects of implementing these measures.
The results of screening in 6-month periods from January 1995 to December 1997 were determined. Biopsy follow-up for results in the high grade epithelial abnormality ("HGEA") and "inconclusive: possible HGEA" categories was obtained from the Western Australian Cervical Cytology Registry (CCR).
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 category, they were 0.24%, 0.18%, 0.24%, 0.31%, 0.38%, and 0.35% (P < 0.001). Biopsy 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 inconclusive cases.
There was a doubling in the reporting of HGEA results, whereas the positive predictive value for biopsied cases remained at about 80%. Reporting rates for inconclusive: possible HGEA cases also doubled, but the yield of biopsy-proven, high grade lesions remained at about 50%. These changes occurred in the absence of ancillary testing and with targeted rescreening methods. A high rate of reporting HGEA, in combination with a high positive predictive value, is among the most important indicators of cervical cytology laboratory performance. Large improvements in results may occur using conventional methods of quality assurance. Cancer (Cancer Cytopathol)