The reliability of pre-transplant donor renal biopsies (PTDB) in predicting the kidney state. A comparative single-centre study on 154 untransplanted kidneys

Background. Pre-transplant donor biopsy (PTDB) is a common practice in marginal donors, taking for granted that it represents the whole kidney state, but its reliability has not yet been thoroughly investigated. This prompted us to carry out a comparative study on a needle biopsy group (NBG) and a wedge biopsy group (WBG) and their corresponding untransplanted kidneys. Methods. One hundred and fifty-four biopsies and matched kidneys were scored for four morphologic indexes, i.e. tubular atrophy, interstitial fibrosis, vascular damage and global glomerulosclerosis. Categorical indexes were statistically evaluated for concordance with the k index, and the percentage of sclerotic glomeruli with correlation and linear regression analysis. Results. Agreement between biopsies and kidneys was similar in both NBG and WBG with high scores for vascular damage (k 0.74 and 0.75) and intermediate ones for tubular atrophy (k 0.54 and 0.50). Agreement as to fibrosis and glomerular sclerosis was intermediate in the WBG (k 0.56 and 0.55) and poor in the NBG (k 0. 34 and 0.18). Vascular damage was underscored and glomerulosclerosis overscored in both groups, whereas interstitial fibrosis was underscored in the NBG and overscored in WBG. The agreement for the total score, i.e. the sum of the single indexes, was high in the NBG (k 0.73) and intermediate in WBG (k 0.57). Agreement for glomerulosclerosis and total score rose consistently in both groups along with the increasing number of biopsy glomeruli. There was an agreement as to biopsy and kidney evaluation for fitness for transplantation in 85% of NBG and 81% of WBG. Conclusions. PTDB supplies reliable data on the actual kidney state, with better results for needle biopsy. Although the biopsy size plays a role, samples with over 10 glomeruli suffice for clinical purposes. Vascular damage is the most faithful single parameter, whereas global glomerulosclerosis estimation requires some caution.