CELL-TYPE IDENTIFICATION IN LEUKEMIA - THE LEVEL OF AGREEMENT AMONG 4INDEPENDENT DIAGNOSTIC METHODS

The level of agreement among four independent diagnostic methods for c ell-type identification in leukemia was examined. The four diagnostic methods were routine morphology, electron microscopy, cell surface mar ker analysis by flow cytometry, and cancer cytogenetics. Sixty-five bl ood and bone marrow samples from fifty-seven patients were independent ly investigated by the four methods. It was found that when all cell-t ype categories were taken into consideration, overall percentages of a greement for pairs of the four diagnostic methods were poor, ranging f rom 43% to 67%. The kappa statistics, which correct for the agreement expected by chance, were also calculated. These kappa statistics had a range from 0. 17 to 0.40 when all cell-type categories were taken int o consideration, again indicating poor agreement between the methods p airwise. When each cell type was considered separately, much of the ob served agreement was found to be expected on the basis of chance, as i ndicated by many of the kappa statistics being 0.00. For all categorie s, overall agreement for all four methods was poor and statistically s ignificant, after correcting for chance (kappa = 0.20, p = 0.000046). The poor agreement found among the four diagnostic methods indicates t he need for further validation studies.