Tumor grading in urinary cytology. A study of the cytohistological relationship with evaluation of the kappa statistic for concordance

: In order to verify both usefulness and reliability of cytologic grading evaluated on urinary sediment, we designed a study to test the ability to distinguish consistently between different degrees of neoplastic abnormalities of urothelial cells from voided urine, in relation to the histologic findings of bladder biopsies performed after cytologic reading. Kappa measures were calculated in 112 cytohistologic pairs representative of first disease detection (A) and in 35 pairs representative of disease recurrence (B). Cytology was able to correctly identify a cancer in 70.5% and 80.0% of group A and group B lesions, respectively. Unweighted kappa values of both groups A and B were poor (0.298 and 0.324 respectively). When we considered the weighted kappa, values suggesting fair agreement were obtained (0.576 and 0.500). Our data confirm that urinary cytology shows a good sensitivity in detecting bladder cancer, but it does not seem to give reliable results for the assessment of the tumor grading.