Using urbanization profiles to assess screening performance.

The large Dutch data sets acquired as a result of population-based cervical smear screening programs can be further exploited to obtain an urbanization-weighted score to gain insight into the quality of the performance of the individual cytology laboratories. Based on the first four digits of the postal code of the screenees, the data are stratified according to urbanization. Urb 1 corresponds to (semi)rural, which includes villages and small townships with less than 20,000 inhabitants; Urb 2, to towns with between 20,000 and 250,000 inhabitants; and Urb 3, to big cities, in this case, The Hague. From the postal code data of the screenees, the urbanization profiles of the laboratories can be calculated. The urbanization degree proved to have a substantial effect on the cytologic scores in the four laboratories. The number of expected, urbanization-weighted patient cases is calculated. Accordingly, the laboratories could be compared with respect to performance. We conclude that laboratories in our screening program were quite similar in performance for the cytologic diagnosis leading to referral to the hospital, with little difference between the actual and the expected, urbanization-weighted number of cases. It is evident that the equation for calculating the expected scores for S5-S9 is relevant for control of quality of care provided by laboratories and regions, but also for the quality of these assessments.