REPRODUCIBILITY OF THE BANFF CLASSIFICATION OF RENAL-ALLOGRAFT PATHOLOGY - INTEROBSERVER AND INTRAOBSERVER VARIATION

The present study was undertaken to investigate the inter- and intraob server variation in use of the scoring system for glomerulitis, vascul itis, interstitial inflammation, tubulitis and arteriolar hyalinosis t hat is an essential part of the recently proposed Banff classification of renal allograft biopsies, Seventy-seven biopsies done less than 90 days after transplantation were included. The scoring was done blindl y by five pathologists on biopsies stained with H&E and PAS, The volum e fraction of interstitial inflammation was estimated, Spearman rank c orrelation coefficient and kappa values were used for the evaluation o f reproducibility, The results of both inter- and intraobserver variab ility showed a good correlation and reasonable kappa values for vascul itis, interstitial inflammatory infiltration, and tubulitis, Less-good correlation was found for glomerulitis and arteriolar hyalinosis, The interobserver kappa score for grading of the rejection severity was 0 .40 overall but 0.56 when only presence or absence of acute rejection was considered and 0.66 for presence or absence of vasculitis, Weighte d kappa values for interobserver vasculitis score and rejection gradin g were 0.58 and 0.55, respectively, A strong association existed betwe en the volume fraction of interstitial inflammation and the semiquanti tative scoring for interstitial inflammation, In conclusion, the good correlations for the key elements in the grading of the allograft biop sies in the present classification system, confirmed the utility of th e defined criteria for grading rejection, More precisely defined crite ria or simplification of the scoring system are needed for glomeruliti s and arteriolar hyalinosis-parameters not used in the diagnosis of re jection