INTEROBSERVER VARIATION IN CYTOLOGICAL AND HISTOLOGICAL DIAGNOSES OF CERVICAL NEOPLASIA AND ITS EPIDEMIOLOGIC IMPLICATION

Inter-observer variation in cytohistological diagnosis was assessed fo r 1506 cervical smears and 883 histological slides from four case-cont rol studies on cervical neoplasia. The kappa statistic among a panel o f three cytopathologists was highest for diagnosis of invasive cancer (0.70 for cytology and 0.74 for histology), followed by normal/inflamm atory in cytology (0.68) and CIN III in histology (0.58). There was al so nearly perfect agreement between the final panel diagnoses and the original diagnoses made by local cytopathologists, except for those of CIN III. Inter-observer variation in diagnosis for CIN III was invers ely associated with age, number of children (in histology) and sexual activity (in cytology). However, the odds ratios for CIN III calculate d by each cytopathologist's diagnosis were not different from each oth er for any etiologic factor. These results indicate that the diagnoses of invasive cancer and of normal/inflammatory changes are highly repr oducible and that the inter-observer variation does not have much impa ct on the etiologic risk estimates.