A model for quality assessment in cervical cytology used as a screening test

Although many reliability studies on cervical cytology have been carried out, measurements of sensitivity and specificity have rarely been made since biopsies are not often performed on patients with a negative smear result. This screening assessment was performed over 3 years, using a database of 230,167 smears from 177,051 women. It would seem that cervical cytology has a high specificity (over 99%) but a relatively low sensitivity (61%). Values for sensitivity (exceeding 95%) and specificity (exceeding 99%) for invasive carcinoma should be regarded as reasonably accurate as all incident cases of symptomatic cervical carcinoma are recorded in the Burgundy register. The sensitivity (57%) for pre-invasive lesions is underestimated while their prevalence is overestimated: the lack of organized screening leads to the loss of prevalent cases. The predictive value of a positive smear is 76% for moderate-severe dysplasia, 85% for in situ carcinoma and over 95% for invasive carcinoma.