External Quality Assessment of First-Trimester Prenatal Biochemical Screening in China

Free β subunit of human chorionic gonadotropin (free β-hCG) and pregnancy-associated plasma protein A (PAPP-A) are two important biomarkers in first-trimester prenatal screening. This study intended to reflect their analytical performance in clinical laboratories and main platforms of the 2015 External Quality Assessment (EQA) scheme for the first-trimester biochemical screening in China.

Ten lyophilized EQA samples, divided into two sets and analyzed in two cycles 20151 and 20152, were distributed to each participant in 2015. Satisfactory performance was defined as scores more than 80 of acceptable results within the evaluation criterion of ± 30%. The robust coefficient of variability (CV) of each sample was calculated by analytes and mainstream platforms. The chi-square (2) test and the Mann-Whitney test were respectively used to compare the acceptable performance and the robust CV between two analytes, as well as two mainstream platforms.

A total of 142 laboratories were enrolled in this EQA scheme. For free β-hCG and PAPP-A, the number of effective results were 1330 and 1355, respectively, and the overall acceptable rates of results were 95.11% and 92.32%, respectively. For cycle 20151 and 20152, the acceptable rates were respectively 92.59% and 96.19% for free β-hCG and 89.78% and 94.78% for PAPP-A. The 2 test showed acceptable performance differed significantly between the two analytes, as well as two platforms for PAPP-A. Significant difference of the robust CV in different analytes and platforms was demonstrated by Mann-Whitney test.

Greater than 92% of results were acceptable. However, continuous improvement and further research of this EQA scheme is in process.