Wald Nicholas J, Rudnicka Alicja R, Bestwick Jonathan P
Wolfson Institute of Preventive Medicine, Barts and the London Queen Mary's School of Medicine and Dentistry, London EC1M 6BQ, UK.
Prenat Diagn. 2006 Sep;26(9):769-77. doi: 10.1002/pd.1498.
To compare the Integrated test in three policies for prenatal Down syndrome screening: Integrated screening for all women, sequential screening (first-trimester tests allowing early completion of screening for high-risk pregnancies), and Contingent screening (early completion of screening for high- and low-risk pregnancies).
Estimation of detection rates (DRs) and false-positive rates (FPRs) using Monte Carlo simulation and cost effectiveness for each method.
Down syndrome affected and unaffected pregnancies studied in the Serum Urine and Ultrasound Screening Study (SURUSS). RESULTS AND MAIN OUTCOMES: Integrated screening has the best screening performance. The performance of the other two policies approached that of Integrated screening as the first-trimester test FPR decreased. If the first-trimester FPR is set to 0.5% (risk >or= 1 in 30) with an overall DR of 90%, sequential and contingent screening yield overall FPRs of 2.25% and 2.42%, respectively, and 66% of the affected pregnancies are detected by the first-trimester test. The Integrated test on all women yields an FPR of 2.15%. With sequential screening, 99.5% of women would proceed to an Integrated test, or 30% with contingent screening if those with first-trimester test risks of <or=1 in 2000 are classified screen-negative and receive no further testing. About 20% of affected pregnancies identified in the first trimester using sequential or contingent screening would have unnecessary terminations (they would miscarry before the early second trimester). Contingent screening is the most cost-effective if there is no alphafetoprotein screening for neural tube defects, otherwise Integrated screening is more cost-effective.
Integrated screening for all women is the simplest, most effective, and the safest policy. Contingent screening is the most complex with the lowest screening performance. Making an earlier diagnosis with sequential and contingent screening has adverse consequences that are sufficient to discourage their use.
比较三种唐氏综合征产前筛查策略的综合检测效果，这三种策略分别是：对所有孕妇进行综合筛查、序贯筛查（孕早期检测以便对高危妊娠尽早完成筛查）和应急筛查（对高危和低危妊娠尽早完成筛查）。
采用蒙特卡罗模拟法估算每种方法的检测率（DRs）和假阳性率（FPRs），并评估其成本效益。
在血清、尿液及超声筛查研究（SURUSS）中对唐氏综合征患儿及正常胎儿的妊娠情况进行研究。
综合筛查具有最佳的筛查效果。随着孕早期检测假阳性率的降低，其他两种策略的效果接近综合筛查。如果将孕早期假阳性率设定为0.5%（风险≥1/30），总体检测率为90%，序贯筛查和应急筛查的总体假阳性率分别为 2.25%和2.42%，且66%的唐氏综合征患儿妊娠可通过孕早期检测发现。对所有孕妇进行综合检测的假阳性率为2.15%。采用序贯筛查时，99.5%的孕妇将进行综合检测；采用应急筛查时，如果孕早期检测风险≤1/2000的孕妇被判定为筛查阴性且不再接受进一步检测，那么30%的孕妇将进行综合检测。在孕早期采用序贯筛查或应急筛查发现的唐氏综合征患儿妊娠中，约20%会进行不必要的引产（这些胎儿会在孕中期早期之前发生自然流产）。如果不进行神经管缺陷的甲胎蛋白筛查，应急筛查是最具成本效益的，否则综合筛查更具成本效益。
对所有孕妇进行综合筛查是最简单、最有效且最安全的策略。应急筛查最为复杂，筛查效果最差。序贯筛查和应急筛查进行的早期诊断会产生不良后果，足以使其不被采用。
