Analytical and Clinical Performance of a Novel Immunoassay-Based Test System to Predict Diabetic Kidney Disease

Background Diabetes-related chronic kidney disease (DKD) is a leading cause of end-stage kidney disease (ESKD), requiring costly dialysis or kidney transplantation. Existing standard- of-care tests for DKD have several limitations, and an alternative is Promarker®D, a validated plasma biomarker test system that predicts DKD in adults with diabetes up to 4 years before symptoms develop. Methods To enable high-throughput application of PromarkerD, a novel CaptSureTM immunoassay version of the test was developed targeting plasma biomarkers Apolipoprotein A4 (ApoA4) and CD5 antigen-like (CD5L). The analytical performance of the assay was assessed, and clinical samples from 2 independent clinical cohorts (>1700 adults with type 2 diabetes [T2D]) were used for the development and external validation of the DKD predictive test. Results The PromarkerD test system combined ApoA4 and CD5L concentrations with clinical factors age and estimated glomerular filtration rate (eGFR) to calculate risk scores (0% to 100%) and classify study participants as either at low, moderate, or high risk for future kidney decline. PromarkerD demonstrated reliable analytical performance and provided a high discriminative capability in adults with T2D (receiver operating characteristic area under the curve [ROC-AUC]: 0.78 to 0.88) to predict 4-year kidney decline, defined as incident DKD (eGFR <60 mL/min/1.73 m2) or eGFR decline ≥40%, with sensitivity of 75.8% to 85.1% at the moderate-risk cutoff and specificity of >92% at the high-risk cutoff across the two cohorts. Conclusion The next-generation PromarkerD test system offers a convenient yet highly effective tool for DKD risk assessment. By introducing PromarkerD to standard diabetes care, preventative treatment strategies may be implemented early before permanent kidney function loss occurs.