Nephron Number and Time to Remission in Steroid-Sensitive Minimal Change Disease

Abstract

Rationale & ObjectiveThe response to corticosteroid therapy may differ among patients with minimal change disease (MCD). Previous studies have suggested that glomerular hypertrophy or low areal glomerular density in biopsy specimens, which may be related to fewer nephrons, is associated with such a difference. We examined the associations between nephron number and the therapeutic response to corticosteroids in patients with MCD.Study DesignRetrospective cohort study.Setting & Participants75 adult patients with a histologic diagnosis of MCD.ExposureNephron number per kidney estimated based on the combination of unenhanced computed tomography and nonsclerotic volumetric glomerular density in kidney biopsy specimens.OutcomesComplete remission and relapse following corticosteroid therapy.Analytical ApproachMultivariable Cox proportional hazard analyses of associations between factors, including nephron number, and outcomes.ResultsMean age of patients was 45.9 years and 60.0% were men. Patients had an estimated glomerular filtration rate of 64.6 mL/min/1.73 m2 and proteinuria of 8.7 g/d. The estimated total number of nonsclerotic glomeruli ranged from 1.07 to 18.77 ×105 per kidney among all patients. There were no significant differences in total amounts or selectivity of urinary protein excretion at biopsy among the tertile groups categorized by nephron number. All patients responded to corticosteroid therapy, but those with fewer nephrons had a delayed achievement of complete remission. Multivariable Cox proportional hazard analyses identified nephron number as a significant independent explanatory variable for the achievement of complete remission, with a hazard ratio of 1.10 (95% CI, 1.02-1.19)/100,000 nephrons per kidney. Nephron number in these patients was not associated with achievement of partial remission or relapse following complete remission.LimitationRetrospective design and sampling bias of needle biopsy.ConclusionsA small nephron number in patients with MCD is associated with longer time to complete remission.