The new histopathologic classification of ANCA-associated gn and its association with renal outcomes in childhood

Abstract

Background and objectives A proposed histopathologic classification for ANCA-associated GN is predictive of long-term renal outcome in adult populations. This study sought to validate this system in a pediatric cohort. Design, setting, participants, & measurements This was a retrospective, single-center, cohort study of 40 children diagnosed and followed until their transition to adult care at one institution between 1987 and 2012. Renal biopsy specimens were reviewed by a pathologist blinded to patient outcome and were classified using the new histopathologic classification system of focal, crescentic, mixed, and sclerotic groups. Time to the composite outcome of CKD stages 3 and 4 (determined by eGFR with repeated creatinine measures using the Schwartz equation) or ESRD (defined as dialysis dependence or transplantation) were ascertained. Results The study population consisted of 40 children (70%female), followed for amedian of 2.4 years. The biopsy specimenswere categorized as focal in 13 patients (32.5%), crescentic in 20 (50%),mixed in two (5%), and sclerotic in five (12.5%). Mixed and crescentic were combined for analyses. Survival analysis of time to the composite renal endpoint of at least 3 months of eGFR,60 ml/min per 1.73 m2 or ESRD differed significantly among the three biopsy groups log-rank P,0.001), with an adjusted hazard ratio of 3.14 (95% confidence interval, 0.68 to 14.4) in the crescentic/mixed group and 23.6 (95% confidence interval, 3.9 to 144.2) in the sclerotic category comparedwith the focal category. The probability of having an eGFR.60 ml/min per 1.73m2 at 2 years was 100% for the focal, 56.5% for the crescentic/mixed, and 0% for the sclerotic biopsy categories. Conclusions This study showed the clinical utility of this histopathologic classification system and its ability to discriminate renal outcomes among children with ANCA GN.