Egan J F, Benn P, Borgida A F, Rodis J F, Campbell W A, Vintzileos A M
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, Connecticut, USA.
Obstet Gynecol. 2000 Dec;96(6):979-85. doi: 10.1016/s0029-7844(00)01044-9.
To estimate the 16-week prevalence of Down syndrome in the United States from 1974 to 1997 and to determine the efficacy of maternal age cutoffs and triple screens for detecting it antenatally.
Using natality statistics for the United States from 1974 to 1997 of maternal-age-specific live births to women 13-49 years old, we evaluated advanced maternal age (35-49 years at delivery) and the triple serum test (maternal serum alpha-fetoprotein, hCG, and unconjugated estriol) as screening tests for Down syndrome. Efficacy was evaluated using sensitivity, false-positive rate, positive predictive value, and likelihood ratio (likelihood ratio = sensitivity/false-positive rate).
In 1974, the estimated second-trimester prevalence of Down syndrome was one in 740, but by 1997 that had increased to one in 504. The proportion of Down syndrome fetuses at 16 weeks' gestation in women 35-49 years old increased from 28.5% in 1974 to 47.3% in 1997. However, live births to women 35-49 years old increased more rapidly from 4.7% in 1974 to 12.6% in 1997. The likelihood ratio for maternal age to identify an affected pregnancy decreased during the study period and was substantially lower than that using the serum test.
A maternal age cutoff of 35 years in the 1990s resulted in high false-positive rates and was less efficacious based on likelihood ratio and positive predictive value. Serum testing of all pregnant women would reduce the number of amniocenteses and decrease procedure-related losses.
评估1974年至1997年美国唐氏综合征的16周患病率，并确定产妇年龄截断值和三联筛查在产前检测唐氏综合征的有效性。
利用1974年至1997年美国针对13至49岁女性按产妇年龄分类的活产出生统计数据，我们评估了高龄产妇（分娩时年龄为35至49岁）和三联血清检测（母体血清甲胎蛋白、人绒毛膜促性腺激素和非结合雌三醇）作为唐氏综合征的筛查检测方法。使用灵敏度、假阳性率、阳性预测值和似然比（似然比=灵敏度/假阳性率）评估有效性。
1974年，估计孕中期唐氏综合征患病率为1/740，但到1997年已增至1/504。35至49岁女性妊娠16周时唐氏综合征胎儿的比例从1974年的28.5%增至1997年的47.3%。然而，35至49岁女性的活产率增长更快，从1974年的4.7%增至1997年的12.6%。在研究期间，产妇年龄识别受影响妊娠的似然比下降，且远低于使用血清检测的似然比。
20世纪90年代将产妇年龄截断值设定为35岁导致假阳性率较高，基于似然比和阳性预测值，其有效性较低。对所有孕妇进行血清检测将减少羊膜穿刺术的次数，并降低与该操作相关的损失。
