A-084 Evaluation of the Analytical Performance Creatinine_3 Assay on the Atellica CH and CI Analyzers

Abstract Background The Atellica CH Creatinine_3 (Crea3) assay measures creatinine, a renal function marker, in human serum, plasma, and urine. This study evaluated the analytical performance of the Atellica CH Crea3 assay on Atellica CH and CI analyzers. Methods Precision studies were performed per CLSI EP05-A3 using native human and spiked serum, urine, and quality control samples. Repeatability and within-lab precision samples were tested in duplicate, 2 runs/day for 20 days (n=80). Reproducibility samples were assayed in five replicates, 1 run/day for 5 days (n=225), 3 instruments, 3 reagent lots. Method comparison (MC) studies used the Deming regression model per CLSI EP09c and compared the Atellica CH Crea3 assay (y) (serum and urine) to the Atellica CH Crea_2 assay (x), and the Atellica CH Crea3 assay on the Atellica CI (y) and Atellica CH (x) analyzers. Limit of blank, detection, and quantitation (LoB, LoD, and LoQ) samples were tested per CLSI EP17-A2. Linearity studies were performed per CLSI EP06-ED2 and specimen equivalency, per CLSI EP09c. Results Atellica CH analyzer: Precision serum repeatability coefficients of variation (CVs) were 0.2–3.2% and within lab, 1.1–4.0% at 0.38-28.54 mg/dL (34-2523 µmol/L); urine repeatability CVs were 0.1–0.2% and within lab CVs, 1.2–1.3% at 56.74–195.79 mg/dL (5016–17,308 µmol/L). Reproducibility CVs for serum were 0.9–5.0% at 0.40-28.76 mg/dL (35–2542 µmol/L) and for urine 1.4–1.6% at 57.23–199.45 mg/dL (5059–17,631 µmol/L). MC Deming regression equations were y=1.00x-0.04 mg/dL ( y=1.00x-4 µmol/L) at 0.44–28.64 mg/dL (39–2532 µmol/L) (serum) (n=151; r=1.000), and y=1.00x+0.14 mg/dL (y=1.00x+12 µmol/L) at 12.60–237.06 mg/dL (1114–20,956 µmol/L) (urine) (n=113; r=1.000). Atellica CI analyzer: Precision serum repeatability CVs were 0.4–4.0% and within lab, 0.7–4.0% at 0.40–28.75 mg/dL (35–2542 µmol/L); urine repeatability CVs were 0.3–0.4% and within lab CVs were 0.7–1.1% at 56.62–195.39 mg/dL (5005–17272 µmol/L). Reproducibility CVs for serum were 0.6–12.2% at 0.41–29.00 mg/dL (36–2564 µmol/L) and for urine 1.2–1.4% at 56.68–196.76mg/dL (5011–17394 µmol/L). MC Deming CI vs CH regression equations were y=1.00x+0.02 mg/dL (y=1.00x+2 µmol/L) at 0.46–28.89 mg/dL (41–2554 µmol/L) (serum) (n=151; r=1.000), and y=0.97x+0.22 mg/dL (y=0.97x+19 µmol/L)) at 12.50–235.17 mg/dL (1105–20789 µmol/L) (urine) (n=113; r=1.000). For both Atellica CH and CI analyzers, LoB, LoD, and LoQ were 0.05, 0.10, 0.15 mg/dL (4, 9, 13 µmol/L) (serum/plasma), and 0.50, 1.00, 3.00 mg/dL (44, 88, 265 µmol/L) (urine); linear range was 0.15–30.00 mg/dL (13–2652 µmol/L) (serum/plasma) and 3.00–245.00 mg/dL (265–21,658 µmol/L) (urine). Specimen equivalency on Atellica CH analyzer for sodium heparin-, lithium heparin-, and dipotassium EDTA plasma vs. serum yielded slopes 0.98–1.00 and intercepts 0.00–0.06 mg/dL (0–5 µmol/L). Conclusion The Atellica CH Crea3 assay demonstrated acceptable analytical performance on Atellica CH and CI analyzers; MC results for Crea3 and Crea_2 assays were similar for the same specimen type.