GLOMERULAR SCORE AS A PROGNOSTICATOR IN IGA NEPHROPATHY - ITS USEFULNESS AND LIMITATION

Glomerular sclerosis, mesangial hypercellularity, extracapillary lesio ns, interstitial fibrosis, and vascular sclerosis have been reported t o be the significant pathologic prognosticators in IgA nephropathy (Ig AN). We developed our own scoring for the following main glomerular ch ang es in 248 patients with IgAN: 1) glomerular hypercellularity (mesa ngial and endocapillary), 2) segmental lesions such as tuft adhesion, crescent and segmental sclerosis, 3) global glomerular sclerosis. Indi ces of each lesion were semiquantitatively determined. The sum of thes e three indices was defined to be a glomerular score. We found that a glomerular score significantly related to the outcome of patients with IgAN in univariate life table analysis. We also semiquantitatively de termined total score including tubulo-interstitial and vascular lesion s as well as glomerular score and compared the predictive power as a p rognosticator between glomerular score and total score. Using Cox's pr oportional Hazard model and log-likelihood ratio test, we confirmed th at predictive power of glomerular score was better than that of total score. Furthermore, we assessed the reproducibility of glomerular scor e using Kappa statistics. Three pathologists read 100 biopsies which w ere randomly selected from the materials and all pathologists read the m twice. A value of Kappa between the first and second observation of pathologist A, B and C was 0.68, 0.71 and 0.60, respectively. Values o f Kappa between Pathologist A and B were ranging from 0.45 to 0.47, th ose between Pathologist A and C from 0.30 to 0.36, and finally those b etween Pathologist B and C were ranging from 0.12. to 0.23. Therefore, intra-observer reproducibility was nearly excellent. And inter-observ er reproducibility between Pathologist A and B was satisfactory. Howev er, inter-observer reproducibility between Pathologist A and C and bet ween B and C was not satisfactory. We feel our scoring system is very convenient and easy to be understood as a prognosticator in patients w ith IgAN. It, however, should be used by one pathologist because of ex cellent intra-observer reproducibility and rather unsatisfactory inter -observer reproducibility.