Quality assurance in cervical screening of a high risk population: a study of 65,753 reviewed cases in Parana Screening Program, Brazil.

Epidemiological data from the Quality Assurance Unit (QAU) of the Cervical Cancer Screening Program of Paraná is discussed. Slides (65,753) reviewed by the QAU, from October 1997 to July 1999, were analyzed. Relations between agreement rate, diagnostic categories, and age groups were tested. The overall agreement rate was 97.04% (kappa +/- 95%, confidence interval = 0.888 +/- 0.003). Low-grade squamous intraepithelial lesion (LSIL) showed its peak prevalence in patients < or = 19 yr (8.3%). High-grade squamous intraepithelial lesion (HSIL) was more common in women between 40 and 49 yr (5.0%). Squamous-cell carcinoma (SCC) was almost exclusively seen in women > or = 40 yr. The lowest agreement rates were seen in adenocarcinoma (54.5%; kappa = 0.667) and LSIL cases (76.3%, kappa = 0.822), and in women < or = 19 yr (95.8%). It was concluded that constant monitoring to assess specific errors allows directed measures. The 10% rescreening model of quality assurance proved to be effective in a low resources setting with a positive overall financial impact.