EXTERNAL QUALITY ASSURANCE IN CERVICAL VAGINAL CYTOLOGY - INTERLABORATORY AGREEMENT IN THE EMILIA-ROMAGNA REGION OF ITALY/

OBJECTIVE: To evaluate the diagnostic agreement between seven cervical /vaginal cytology laboratories participating in the first external qua lity assurance (EQA) scheme developed in Italy. STUDY DESIGN: Between 1991 and 1993, 110 cytologic smears were selected and classified by a committee and circulated and reported on by the laboratories according to the 1988 Bethesda System. Agreement was evaluated with the kappa s tatistic. Systematic disagreement cons assessed by means of the Wilcox on signed rank test. RESULTS: Interlaboratory kappa values varied betw een .01 and .29 (group score, .11) for sample adequacy and between .53 and .78 (group score, .67) for epithelial abnormalities. Tile lowest specific kappa values were observed for the three classes of sample ad equacy (unsatisfactory, .07; less than optimal [LTO], .10; satisfactor y [SAT], .14) and for the class of atypical cells of undetermined sign ificance (ACUS), (.29). As compared with the study committee, 5/7 labo ratories showed a systematic (P < .01) tendency to under-call sample a dequacy. Agreement on epithelial abnormalities tons also analyzed acco rding to the pattern of adequacy reported by paired laboratories (LTO/ LTO, LTO/SAT, SAT/SAT). As compared with smears desig nated SAT/SAT, t hose classified as LTO/SAT were associated with lower specific kappa v alues for agreement on the presence of carcinoma and ACUS and with equ al or greater values for agreement on the other classes, suggesting an arbitrary use of notations of LTO inversely related to the severity o f epithelial lesions. CONCLUSION: EQA schemes, as applied to cervical/ vaginal cytology, can shed light on major deficiencies in specific dia gnostic areas.