The quality of veterinary in-clinic and reference laboratory biochemical testing

Background: Although evaluation of biochemical analytes in blood is common in veterinary practice, studies assessing the global quality of veterinary in-clinic and reference laboratory testing have not been reported. Objective: The aim of this study was to assess the quality of biochemical testing in veterinary laboratories using results obtained from analyses of 3 levels of assayed quality control materials over 5 days. Methods: Quality was assessed by comparison of calculated total error with quality requirements, determination of sigma metrics, use of a quality goal index to determine factors contributing to poor performance, and agreement between in-clinic and reference laboratory mean results. The suitability of in-clinic and reference laboratory instruments for statistical quality control was determined using adaptations from the computerized program, EZRules3. Results: Reference laboratories were able to achieve desirable quality requirements more frequently than in-clinic laboratories. Across all 3 materials, > 50% of in-clinic analyzers achieved a sigma metric >= 6.0 for measurement of 2 analytes, whereas > 50% of reference laboratory analyzers achieved a sigma metric >= 6.0 for measurement of 6 analytes. Expanded uncertainty of measurement and +/- total allowable error resulted in the highest mean percentages of analytes demonstrating agreement between in-clinic and reference laboratories. Owing to marked variation in bias and coefficient of variation between analyzers of the same and different types, the percentages of analytes suitable for statistical quality control varied widely. Conclusion: These findings reflect the current state-of-the-art with regard to in-clinic and reference laboratory analyzer performance and provide a baseline for future evaluations of the quality of veterinary laboratory testing.