uE_3在唐氏综合征孕中期多指标联合筛查风险预测中的效果评估

目的通过比较孕妇血清甲胎蛋白(AFP)、绒毛膜促性腺激素β亚单位(β-hCG)两联和AFP、β-hCG、游离雌三醇(uE3)三联两种筛查风险计算模型的检出率、假阳性率和Cut-Off值,探讨uE3在唐氏综合征(DS)产前筛查中的效果。方法收集上海4家保健机构提供的2001~2004年筛查数据,对孕14+~20+周的14642例孕妇的血清学指标和随访结果进行统计分析,应用统计学方法拟合年龄风险与各指标的似然比风险计算模型。分别应用两联筛查风险计算模型、uE3与年龄风险计算模型和三联筛查风险模型进行计算,在3%~8%假阳性率时比较各模型的检出率、阳性预测值和Cut-Off值。在85%检出率的基础上比较各模型的假阳性率、Cut-Off值和阴性预测值。结果①14642例孕妇随访确认为DS的有15例,发病率约1/1000;②比较DS组(1.0787ng/ml)和正常组(1.7125ng/ml)的血清uE3水平,两者存在统计学差异(t=2.96,P<0.01);③比较各模型预测风险检出效果,在5%假阳性率时年龄和uE3组合检出率为46.7%,两联筛查模型为60%,三联模型则为93.3%,两联和三联检出率比较差异有统计学意义(x2=4.658,P<0.05);④在85%的检出率时uE3和年龄因素模型的假阳性率为16.40%,两联模型为7.18%,三联模型则为4.9%,后二者假阳性率存在统计学差异(x2=66.79,P<0.01)。结论uE3在唐氏综合征多指标联合产前筛查中能提高筛查的检出率,减少假阳性率。

Effect of uE3 on Prenatal Screening for Down''''s Syndrome

Objective: To evaluate the effectiveness of uE_3(unconjugated oestriol) in the second-trimester screening for Down's syndrome (DS) by comparing DR(detection rate), FPR(false-positive rate) and Cut-Off value in two formulas. The first formula was established with two serum analytes, namely alphafetoprotein(AFP) and beta subunit of human chorionic gonadotrophin(β-hCG), and the other was established with three analytes (AFP, β-hCG, uE_3). Methods: The data from Beckman Corporation during 2001-2004 were collected and serum of 14,627 women with 14+-20+ weeks' gestation were analyzed. Likelihood ratio in relation to multiples of the median (MOM) levels of these analytes were derived from the overlapping gaussian frequency distribution curves for DS group and unaffected group. Using these different formulas we calculated the DS' risk, and compared the DR, PPV(positive predictive value) and Cut-Off Value when the FPR was 5%, and compared the FPR and Cut-Off when DR was 85%. Results: (1)In 14,642 women, 15 women underwent DS, and the incidence was 1/1000; (2)the uE_3 level in the DS group(1.0787ng/ml)was lower than that (1.7125ng/ml)in normal group, (t=2.96, P<0.01); (3)To compared these formulas, when the FPR was 5%, the DR was 46.7% in the first formula(uE_3+age). It showed 60% in the second formula(AFP+β-hCG+age) and 93.3% in the third one (AFP+β-hCG+uE_3+age). The DR (93.3%, 14/15) in the third formula was higher than that (60%,12/15) in the second formula(x2=4.658,P<0.05); (4)When the DR of these formulas was 85%, the FRP was 16.40% in the first formula, 7.18% in the second formula and 4.9% in the third formula. The FRP in the second formula was higher than that in the third formula(x2=66.79,P<0.01). Conclusion: uE_3 can improve the DR and reduce the FPR in second-trimester screening for Down's syndrome by combination of AFP andβ-hCG.