Abstract
RATIONALE & OBJECTIVE: Few data are available regarding histological features at the time of focal segmental glomerulosclerosis (FSGS) diagnosis among diverse real-world populations. This study describes clinical and histological characteristics and correlates of histological disease severity in adults with FSGS who underwent a clinical kidney biopsy. STUDY DESIGN: Real-world cohort study with data derived from health records. SETTING & PARTICIPANTS: Adults with FSGS by kidney biopsies from Arkana Laboratories from January 1, 2016 to May 31, 2020. EXPOSURE: Race, chronic kidney disease stage, nephrotic proteinuria, age, sex, and hypertension. OUTCOMES: Severe histological disease, defined as global glomerulosclerosis in >50% of glomeruli and >25% interstitial fibrosis and tubular atrophy (IFTA). ANALYTICAL APPROACH: Demographic, clinical, and histological characteristics were compared between race groups. Correlates of severe disease were analyzed using multiple logistic regression. RESULTS: Among 2,011 patients with FSGS, 40.6% were White, and 23.6% Black. White patients were older (52.8 vs 45.5 years, P < 0.001) with a higher estimated glomerular filtration rate (eGFR) than Black patients (53.5 vs 43.1 mL/min/1.73 m(2), P < 0.001). A higher proportion of Black patients had global glomerulosclerosis ≥50% (32.1% vs 14.6%, P < 0.001) or IFTA >50% (34.6% vs 14.7%, P < 0.001). Severe histological disease was more likely in Black patients (OR, 2.46; 95% CI, 1.59-3.79; P < 0.001). A higher proportion of patients with nephrotic than nonnephrotic proteinuria exhibited diffuse foot process effacement. LIMITATIONS: Unequal representation across United States regions, missing demographic and clinical data, and lack of data on primary versus secondary FSGS, treatments, or outcomes. CONCLUSIONS: Black patients were more frequently diagnosed at younger age with lower eGFR and more severe histological disease compared with White patients. Timelier identification of FSGS could increase the opportunity for therapeutic intervention, especially for high-risk patients, to mitigate disease progression and complications. PLAIN-LANGUAGE SUMMARY: Focal segmental glomerulosclerosis (FSGS) accounts for around one-quarter of diagnoses derived from clinical kidney biopsies in the United States. Limited data are available regarding the classes and distribution of histological features at FSGS diagnosis among diverse real-world populations. Analyzing data from US patients who underwent kidney biopsy and were diagnosed with FSGS, we showed that up to half of patients had features of severe histological disease. Of this overall population, Black patients were more frequently diagnosed at a younger age but with more severe histological disease than White patients. The work highlights the need for timelier diagnosis of FSGS to enable intervention at an earlier disease stage.