Kidney Biopsy Findings Among Patients With Diabetes in the Cleveland Clinic Kidney Biopsy Epidemiology Project

Abstract

Rationale & ObjectiveDiabetic Kidney Disease (DKD) is a significant complication of diabetes mellitus, often leading to kidney failure. The absence of well-defined factors prevents distinguishing DKD from Non-Diabetic Kidney Disease (non-DKD; alternative primary diagnosis identified on kidney biopsy). Study DesignRetrospective cohort study. Setting& Participants: 1,242 patients with a history of diabetes from the Cleveland Clinic Kidney Biopsy Epidemiology Project between January 2015 and September 2021. ExposureProteinuria, retinopathy, A1c and eGFR. OutcomesNon-DKD, defined as an alternative primary diagnosis identified on kidney biopsy other than DKD. Analytical ApproachMultivariate logistic regression model with backward elimination method. ResultsAt the time of biopsy, the median (IQR) age was 63 (53-71) years, 58.8% were male, hemoglobin A1c was 6.7% (6.0-8.1), and serum creatinine was 2.5 (1.6-3.9) mg/dL. Among 1,242 patients, 462 (37.2%) had DKD alone, and 780 (62.8%) had non-DKD. Among those with non-DKD, the most common diagnoses were focal segmental glomerulosclerosis (24%), global glomerulosclerosis NOS (13%), acute tubular necrosis (9%), IgA nephropathy (8%), ANCA vasculitis (7%), and membranous nephropathy (5%). Factors associated with having non-DKD on biopsy were having no retinopathy (vs retinopathy) (adjusted odds ratio [aOR], 3.98; 95% CI, 2.69-5.90), lower A1c (<7% vs. ≥7%) (aOR, 3.08; 95%CI, 2.16-4.39), higher eGFR (≥60 vs. <60 ml/min/1.73m2) (aOR, 2.39; 95%CI 1.28-4.45), microalbuminuria (<300 vs. macroalbuminuria ≥300 [mg/g]) (aOR; 2.94; 95%CI, 1.84-4.72), and lower protein to creatinine ratio in random urine (<3 vs. ≥3mg/mg) (aOR; 1.80; 95%CI, 1.24-2.61). LimitationsSelection bias of clinically indicated biopsies, not protocol biopsies, which likely represent a ceiling (maximum) for non-DKD. ConclusionsAmong diabetic patients undergoing kidney biopsy, 63% have findings in addition to DKD on biopsy. We identified clinical parameters associated with non-DKD in the setting of diabetes. This provides valuable information for clinicians when kidney biopsy should be considered among diabetic patients to capture all etiologies of proteinuria and kidney dysfunction.