Abstract: FR-PO0638
Epidemiology of Primary FSGS (pFSGS): Challenges Defining Incidence and Prognosis
Session Information
- Glomerular Diseases: Clinical, Outcomes, and Therapeutics Research - ANCA/FSGS
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Mariani, Laura H., University of Michigan, Ann Arbor, Michigan, United States
- Amitay, Efrat, Boehringer Ingelheim International GmbH, Ingelheim am Rhein, RP, Germany
- Joseph, Corey, Boehringer Ingelheim Corp USA, Ridgefield, Connecticut, United States
- Karandikar, Sangeeta, Arkana Laboratories, Little Rock, Arkansas, United States
- Ambruzs, Josephine M., Arkana Laboratories, Little Rock, Arkansas, United States
- Licariao Rocha, Fabia Tais, Boehringer Ingelheim International GmbH, Ingelheim am Rhein, RP, Germany
- Soleymanlou, Nima, Boehringer Ingelheim Corp USA, Ridgefield, Connecticut, United States
- Trachtman, Howard, University of Michigan, Ann Arbor, Michigan, United States
Background
Focal segmental glomerulosclerosis (FSGS) is a leading cause of nephrotic syndrome and kidney failure. KDIGO defines four subtypes: primary, secondary, genetic, undetermined. Epidemiology of pFSGS is uncertain due to variable diagnostic and classification criteria. We assessed the impact of this variability on published pFSGS incidence and key clinical outcomes, supplemented by a retrospective analysis of a large kidney biopsy database in the US.
Methods
We conducted a systematic review of observational studies (MEDLINE/Embase; published from Jan 2018-Dec 2025; PROSPERO: CRD420251267814) to summarize frequency, clinical features, and outcomes of pFSGS. Two reviewers independently screened studies and extracted data. A retrospective analysis of a US renal biopsy dataset (Arkana Laboratories; 2020-2025) was conducted to estimate the distribution of pFSGS (clinicopathologic findings and ≥80% podocyte foot process effacement [FPE]) vs non-primary FSGS.
Results
The literature review identified 104 studies evaluating pFSGS. Diagnosis was based on kidney biopsy; electron microscopy (EM) use was inconsistent (48/104). Definitions varied from specific light microscopy lesions to degree of podocyte FPE on EM. Reported pFSGS frequency ranged from 2.0-28.2% among kidney biopsies; no population-based prevalence estimates were identified. Annual incidence ranged from 0.039-1.6/100,000, with an upward trend over time in the US – 0.3 (1994-2003), 0.9 (2004-2013), 1.7/100,000 person-years (2010-2021). Despite an expected inverse relationship with FPE thresholds, no clear trend was observed.
Clinically, pFSGS presented with nephrotic syndrome (33.3-91.1%), proteinuria (15.5-100%), and hypertension (17.3-96.7%), with high heterogeneity. Relapse, primarily following steroid treatment, occurred in 40% over 3.5-5 years. Progression to kidney failure increased over time: 10-18% (3 years), 17-25% (5-6 years), 23-36% (>6 years).
Of the 102,556 native biopsies in the Arkana dataset, 5% (n= 4,815) of cases had FSGS and of those, 25% (n=1198) had pFSGS. Notably, pFSGS was more prevalent in younger age groups: <12 (66.4%), 13-17 (50.5%), ≥18 (23.4%).
Conclusion
Published data on pFSGS incidence, presentation, and outcomes vary, largely due to heterogeneity in diagnostic criteria. Established diagnostic criteria and correct classification of pFSGS is essential for better treatment and prognosis.
Acknowledgment
The authors acknowledge the medical writing support provided by YolaRx Consultants Inc. in the preparation of this abstract. This support was funded by Boehringer Ingelheim Pharmaceuticals, Inc.
Funding
- Commercial Support – Boehringer Ingelheim