A-167 Clinical Laboratory Implementation and Analytical Validation of the ELF™ Score for Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) Risk Stratification

Abstract

The Enhanced Liver Fibrosis test (ELF™; Siemens Healthineers) is an FDA-authorized serum biomarker test for assessing metabolic dysfunction-associated steatotic liver disease (MASLD). The ELF score is calculated from hyaluronic acid (HA), amino-terminal pro-peptide of type III collagen (PIIINP), and tissue inhibitor of matrix metalloproteinase 1 (TIMP-1), and has demonstrated prognostic value for MASLD disease progression and liver-related events. This study was aimed at verifying manufacturer’s performance characteristics for ELF including precision, accuracy, reportable range, analyte stability and common interferences. HA, PIIINP, and TIMP-1 testing were performed, and ELF scores calculated using the Siemens ADVIA Centaur XP. Within-run precision was evaluated using 10 replicates of three Siemens ELF QC levels in a single run; between-run precision used 5 replicates across 4 days (n=20). Analytical measuring range (AMR) was verified by testing five Siemens Master Curve Material (MCM) levels in triplicate plus a dilution of level 1. Accuracy was assessed by linear regression analyses of blinded comparisons with three external laboratories (Labs 1–3) using de-identified residual samples from physician-ordered NASH-FibroTest™ (Mayo Clinic Laboratories, BioPredictive). Lab 1 comparison included ELF scores only. Serum on-gel stability (serum separator tube, SST™) was assessed (2 days ambient, 7 days refrigerated). Biotin, lipemia, and icterus interference thresholds were verified by spiking samples (n=3) with 10% saline control or interferent. For hemolysis studies, serum pools were divided into saline control or lab-produced hemolysate (10%) to create five increasing hemolysate concentrations per CLSI EP-07 and analyzed using EP Evaluator. Agreement within 10% for HA, PIIINP and TIMP-1 values, or within 0.3 units for ELF was considered acceptable for method comparison, stability and interference studies. Within- and between-run precision were consistent with manufacturer’s claims for all control levels with coefficients of variation <=5%. Manufacturer AMRs are 3.00–1000.00 ng/mL (HA), 1.00–150.00 ng/mL (PIIINP), and 5.0–1300.0 ng/mL (TIMP-1). MCM material was used to verify 4.00–691.10 ng/mL (HA), 1.70–103.60 ng/mL (PIIINP), and 6.6–1022.6 ng/mL (TIMP-1). Agreement within +/-0.3 ELF score was observed in 25/25, 36/39, and 3/3 samples compared with Labs 1, 2, and 3, respectively. Linear regression analysis yielded y = 0.99x + 0.32 and R2=0.99 for the combined data. For Lab 2, results agreed within 10% for 27/39 HA, 5/39 PIIINP, and 29/39 TIMP-1. For Lab 3, 3/3 samples agreed within 10% for all components. On-gel stability showed 10/10 samples within ±10% for components and ±0.3 for ELF score at both 2-day ambient and 7-day refrigerated conditions. Biotin interference thresholds were verified at 3500 ng/L (HA/TIMP-1), 65 ng/L (PIIINP), and 150 ng/L (ELF score); icterus and lipemia thresholds were verified as I=90 and L=2000, respectively, using Roche serum indices (Roche Diagnostics, Inc.). A hemolysis index (Roche) threshold of 100 was established. Overall, manufacturer’s performance specifications were verified. ELF score comparisons between laboratories demonstrated excellent agreement, even when individual components had differences >10%. Hemolysis studies performed using patient-derived hemolysate demonstrated significant interference from hemolysis at an H-index of 100 which was a novel and notable finding for this testing.