Simulation analysis of 9033 cases of second trimester maternal serum screening for Down's syndrome / 解放军医学杂志

ABSTRACT

Objective To reduce the screening positive rate (SPR) and improve clinical efficiency of maternal serum screening for Down's syndrome.Methods Nine thousand and thirty-three cases of second trimester maternal serum screening for Down's syndrome were included from Apr.2013 to Apr.2014 in the present study.The screening results,all basic data and equation curves were analyzed retrospectively.Based on the data from the authors' laboratory,the important adjustment parameters were simulated.Combined with postnatal follow-up results,the quality and clinical performance of second trimester serum screening for Down's syndrome were evaluated.Results The SPR of second trimester serum screening for Down's syndrome was 6.69％(604/9033),the detection rate (DR) was 75％(3/4),and FPR was 6.65％(601/9033).The median multiple of median (MOM) of alpha-fetoprotein (AFP) was low and SPR was high,and MOM of free human chorionic gonadotropin β subunit (free hCGβ) were high and SPR was high,while MOM of unconjugated estriol (uE3) were a little bit low,and SPR was slightly high.Considering these three factors,it is believed that the screening positive rate is high.By the simulation adjustments of MOM value equations (AFP and free hCGβ) and weight correction equation,the SPR reduced to 4.11％(371/9033) after recalculating the risk,FPR declined to 4.07％(368/9033),and no more Down's syndrome fetus were missed compared with postnatal follow-up results.Conclusion Based on a localized setting depending on the local laboratory data,we suggest that the MOM value distributions(AFP,free hCGβ and uE3) and maternal weight should be regularly adjusted since it is a useful way to reduce the false-positive rate and improve clinical efficiency of maternal serum screening for Down's syndrome.