[1626] Comparison of Staining Methods for Scoring Renal Fibrosis

Christopher Larsen, Christie Boils, Alexis Harris, Fred Silva, Patrick Walker, Nidia Messias. Nephropath, Little Rock, AR; University of Arkansas for Medical Sciences, Little Rock, AR

Background: The best morphologic predictor of outcome for most renal diseases is the degree of interstitial fibrosis (IF). Given this fact, it is of utmost importance that the technique used be accurate and highly reproducible between pathologists. We sought to compare the different stains available for estimation of fibrosis in an effort to determine which one has the best correlation with renal function and the best inter-observer agreement.
Design: Twenty cases with varying degrees of fibrosis were selected in which the indication for biopsy was chronic kidney disease and there was no evidence of acute injury on biopsy. Each case was stained with MT, Jones methenamine silver (JMS), PAS-Trichrome (PT), collagen III immunohistochemistry (Col), and polarized Sirius red (SR). These 100 slides were blindly reviewed and scored by 6 pathologists for degree of severity (none, mild, moderate, severe) and percentage of fibrosis (0-100%). Inter-observer correlation and agreement were evaluated for each stain. We also performed a functional correlation between the percentage of fibrosis and the calculated eGFR for each stain.
Results: Most stains had excellent quantitative scoring interobserver agreement. Interobserver correlation was higher with MT (r=0.72-0.94) and JMS(r=0.79-0.95) than for PT (r=0.59-0.90) and Col (r=0.69-0.90). SR had the least agreement (r=0.32-0.70). Interobserver agreement for grading the degree of fibrosis was highest for MT (κ=0.68) followed by JMS (κ=0.57), PT (κ=0.52), Col (κ=0.51), and SR (κ=0.27). All 5 stains showed correlation with eGFR as follows: TM, r2=0.72; JMS, r2=0.69; PT, r2=0.69; Col, r2=0.61; SR, r2=0.40.
Conclusions: The degree of interstitial fibrosis is a routine but important component of renal biopsy evaluation as this is considered the most important single morphologic predictor of outcome. Nevertheless, there is a paucity of studies addressing the accuracy or reproducibility of the various techniques available for studying this important feature. We confirm here that the most commonly used technique, estimation of fibrosis with MT, shows the best interobserver agreement and correlation with eGFR. Sirius red had the least sensitivity and reproducibility in our hands. JMS, PT, and Col had only slightly lower agreement and eGFR correlation and thus would also be acceptable for routine use.
Category: Kidney (does not include tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 254, Monday Afternoon


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