Standardization of measurement procedures for serum uric acid: 8-year experience from Category 1 EQA program results in China.

Background: Serum uric acid is a critical clinical indicator, and results without equivalence among laboratories cause troubles for disease diagnosis and patient management. External quality assessment (EQA) is a common tool for enhancing harmonization/standardization, therefore, the National Center for Clinical Laboratories in China has initiated a category 1 EQA for serum uric acid measurement since 2010 for evaluating its process of standardization. Methods: Commutable EQA samples with target values assigned by reference measurement procedures were sent to participant laboratories. Both concentrations were measured 15 times in 3 days then means and intra-laboratory coefficient of variations (CVs) were reported. Biological variation criteria were used for analysis with CLIA88 criteria as a comparison. Results: A total of 1250 laboratories participated in EQA programs from 2010 to 2017, pass rates calculated according to desirable specifications in biological variation database were on a rise overall and inter-laboratory mean bias and CVs were on a decrease. Homogeneous systems showed better inter-laboratory CVs and pass rates than heterogeneous systems. For the mostly used measurement systems; Abbott, Beckman, Roche Modular, Siemens and Hitachi showed desirable performances other than Roche Cobas, according to biological variation criteria. Conclusions: Our study provides reliable information on the standardization of measurement procedures for serum uric acid for manufacturers and laboratories. Further improvements for standardization are still needed to make laboratories more patient-centered.