Assessment of enzyme measurement procedures in China through a trueness verification program.

BACKGROUND

Since 2003, the National Center for Clinical Laboratories (NCCL) has organized a network of reference laboratories and several survey programs to improve standardization in China.

METHODS

We analyzed the 2015 trueness verification program to assess the status of enzyme measurement standardization. Commutable serum-based materials were prepared and sent to 10 reference laboratories to assign target values for 2 enzymes (alanine aminotransferase-pyridoxal phosphate [ALT-pp] and γ-glutamyltransferase [GGT]) using IFCC reference measurement procedures.

RESULTS

Analytical performance was assessed for compliance to 3 indexes: trueness (bias), imprecision (CV), and accuracy (total error). Of the 250 participating laboratories, about half (≥124) used heterogeneous systems. More laboratories met the tolerance limit of imprecision than of trueness or accuracy. Except at the lowest concentration, the CV pass rates were >90% for the 2 enzymes. The optimal performance criterion derived from biological variation yielded pass rates for total error (ALT 77%, GGT 80%) that were higher than for bias (ALT 63%, GGT 73%).

CONCLUSIONS

PT/EQA results for commutable samples can be used to assess trueness against reference measurement procedures. Despite global and national standardization programs, bias remains a critical limitation of current enzyme measurement procedures in China.