Analytical Performance Verification of the Beckman Coulter AU5800 Clinical Chemistry Analyser Against Recognized Quality Specifications Reveals Relevance of Method Harmonization.

BACKGROUND: Analytical performance of 24 Beckman-Coulter AU 5800 methods was verified against recognized quality goals and manufacturer's expected imprecision and bias. METHODS: AU5800 method imprecision, bias, agreement with a comparative method, and linearity were studied using CLSI protocols, commercial control material, patient samples, and linearity test kit solutions. Repeat patient testing and IQC were also used for imprecision. Commutability of control material was tested. Total analytical error (TAE) was estimated for each method and between the tested and the comparative method, the Beckman-Coulter Unicel DxC800. RESULTS: CLSI EP15 total imprecision CV (TCV) < 3.2%. Duplicate patient imprecision CV < 2.8%. IQC imprecision CV < 5.1%, except for low level ALP (CV = 7.4%). Sodium and urate IQC imprecision were higher than manufacturer's specifications. TAE for all methods met accepted quality goals. Correlation between methods was > 0.975, except for Cl (0.971), TP (0.964), and Na (0.948). Average bias versus Unicel DxC800 is high for ALP (17.3%), GGT (37%), LD (20%), TBIL (-23%), and TP (8%) and was confirmed in other laboratories. TAE between methods met allowable total error for 21 analytes. For GGT, between method TAE (23 to 51%) was predictable from expected bias and combined method imprecision. For LD and TP several between method differences were outside boundaries describing expected bias. Linearity was excellent with R2 > 0.997 and deviations met accepted goals. CONCLUSIONS: The Beckman-Coulter AU 5800 demonstrates good linearity, low imprecision, and good correlation with previous methods. Observed between method differences suggest ALP, GGT, LD, TBIL, and TP harmonization should be considered.

Results of the recalibration of creatinine measurement with the modular Beckman Coulter Jaffe creatinine method.

BACKGROUND: Serum creatinine is important for detecting the beginning of a decline in kidney function. The Beckman Coulter Jaffe reagents for measuring creatinine have been standardized to the internationally accepted reference method: isotope dilution mass spectrometry (IDMS). The impact of this recalibration on the Beckman Coulter modular or cup (stat) Jaffe method is studied. METHODS: Recalibrated Jaffe (calibrator set points IDMS traceable) and classic National Institute of Standards and Technology (NIST) creatinine methods (traceable to NIST 914a) were compared with an enzymatic method (Sentinel, traceable to NIST SRM 967). All measurements were performed on Synchron DxC 800 systems. Imprecision of the routine methods was studied using the Clinical and Laboratory Standards Institute (CLSI) protocols and laboratory quality survey. Thirteen plasma pools, with concentrations < 354 mmol/L, were analyzed with a gas chromatography isotope dilution mass spectrometry (GC-IDMS) method and routine methods. Total error of 8.2% based on biological variability, set on the GC-IDMS values and acceptance criteria (bias < 5%, imprecision < 8% at concentrations ≥ 88.4 mmol/L and a maximum 10% increase in the relative error of estimated glomerular filtration rate (eGFR) of the National Kidney Disease Educational Program (NKDEP) were used for evaluating analytical performance of the routine methods studied. RESULTS: After recalibration of the Jaffe method, median bias (mmol/L) decreased from 12.4 (95% CI: 9.1-21.2) to 7.3 (95% CI: 1.5-10.5). Imprecision of the Jaffe method is in agreement with the claim of the manufacturer, namely < 9 mmol/L or < 3% below or above 292 mmol/L. Below creatinine of 88.4 mmol/L, imprecision of the recalibrated Jaffe and enzymatic methods is between 4.1% and 6.9%, and 5.0% and 7.1%, respectively, and significantly different (p = 0.02 for both the Jaffe and enzymatic methods) from the goal, based on biological variability, of 2.7%. For the adult pools, all recalibrated Jaffe and enzymatic results fall within the total error of 8.2%. In the pediatric samples, one-third of the recalibrated Jaffe and three of the six enzymatic results fall within this total error goal. CONCLUSIONS: Recalibration significantly reduced bias of the Jaffe method. For pediatric samples, recalibrated Jaffe results do not comply with either the imprecision goal or the total error based on biological variability. Adult recalibrated Jaffe results are in compliance with the goals based on biological variability and with the acceptance criteria from the NKDEP.