Focal Segmental Glomerulosclerosis, Risk Factors for End Stage Kidney Disease, and Response to Immunosuppression

Abstract

Background: Focal segmental glomerulosclerosis (FSGS) is a heterogeneic glomerular disease. Risk factors for end- stage kidney disease (ESKD) and impact of immunosuppression treatment (IST) has varied in previously published cohorts. These cohorts were limited by relatively small case numbers, short follow up, lack of racial/ethnic diversity, a mix of adult and pediatric patients, lack of RAAS inhibition, or lack of subgroup analysis of IST. Methods: We compared demographics, clinical characteristics, histopathology and IST to long term renal survival in a large, ethnically diverse, adult cohort of 338 biopsy-proven FSGS cases with long term follow up in the era of RAAS inhibition using data from the United States Department of Defense health care network. Results: Multivariate analysis showed that nephrotic range proteinuria (NRP), estimated glomerular filtration rate <60 ml/min/1.73m2, hypoalbuminemia, interstitial fibrosis and tubular atrophy, and interstitial inflammation at diagnosis as well as the absence of remission were all associated with worse long term renal survival. IgM, C3, and a combination of IgM/C3 immunofluorescence staining were not associated with reduced renal survival. IST was not associated with improved renal survival in the whole cohort, or in a subgroup with NRP. However, IST was associated with better renal survival in a subgroup of FSGS cases with both NRP and hypoalbuminemia and hypoalbuminemia alone. Conclusion: Our study suggests that IST should be reserved for FSGS patients with nephrotic syndrome. It also introduces interstitial inflammation as a potential risk factor for ESKD and does not support the proposed pathogenicity of IgM and complement activation.