Abstract:

Objective

To assess the effect of protocol focusing on verification of performance of precision and trueness of a biochemistry analysis system on determination of urea, creatinine, glucose and uric acid based on the approach provided by CLSI EP15-A2, and introduce a simple and practical method to improve management quality for clinical laboratories.

Methods

The CLSI EP15-A2 was announced for verification protocol design. Five aliquots of two control materials C1 and C2 were used as precision verification samples.Each aliquot was measured in triplicate in a run every day during 5 days. The repeatability and within-laboratory coefficients of variation (CV) of urea, creatinine, glucose and uric acid determination were estimated and compared with manufacturer′s claim of CVs. If the estimated CVs were less than the claimed CVs, the claim will be verifiable.Five aliquots of two level frozen fresh sera FF1 and FF2 (values assigned by isotope dilution mass spectrometry)were applied as trueness verification samples, each aliquot was measured in duplicate simultaneously with the precision tests. Trueness verification was carried out by whether it was of equivalence statistically between the average of routine biochemistry analysis system and the target value. If the test result was not equivalent to the target value, the bias was further analyzed.

Results

The CVs of urea, creatinine, glucose and uric acid on L1 were 0.61%, 0.56%, 0.64% and 0.61% respectively and the within-laboratory CVs were 1.02%, 0.66%, 0.69% and 0.68%.The CVs of the 4 analytes on L2 were 0.65%, 0.29%, 0.77% and 0.82% respectively, and the within-laboratory CVs were 0.97%, 0.40%, 1.26% and 0.86% respectively. Compared with the specification claimed by manufactory(1.63%, 1.36%, 0.76%, 0.99%, 2.86%, 1.47%, 0.80%, 1.44%, 0.97%, 0.73%, 1.20%, 0.92%, 1.64%, 0.77%, 1.21%,1.0% respectively), the precision of these 4 tests was verifiable. The results of urea, creatinine, glucose and uric acid averaged 9.8 mmol/L, 110.8 μmol/L, 6.3 mmol/L and 489.6 μmol/L on C1, the biases were 2.3%, -2.7%, 0.2% and-1.1% respectively compared with the values assigned by ID-MS methods. The results of urea, creatinine,glucose and uric acid averaged 3.5 mmol/L, 348.9 μmol/L, 11.1 mmol/L and 597.2 μmol/L on C2, and the biases were 3.2%, 0.7%, -2.5% and 2.3% respectively. All the results are of equivalence with target values but urea on FF1. The bias of urea on FF1 (2.3%) met the specification listed in a criterion issued by the minstry of health in 2012.

Conclusion

The verification of performance for precision and trueness of 4 analytes are passed,the CLSI EP15-A2 provides a simple protocol for verification of performance for precision and trueness, and should be applied for performance verification of analysis systems in clinical laboratories.

Key words: Precision, Trueness, Verification