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Integrated screening for Down's syndrome based on tests performed during the first and second trimesters
N J Wald1, H C Watt, A K Hackshaw
1Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, St. Bartholomew's and the Royal London School of Medicine and Dentistry, United Kingdom.
The New England Journal of Medicine
|August 12, 1999
Summary
An integrated screening test combining first and second-trimester measurements improves Down's syndrome detection. This new method offers an 85% detection rate with a significantly lower false positive rate than current screening options.
Area of Science:
- Prenatal diagnostics
- Maternal-fetal medicine
- Genetics
Background:
- Current first and second-trimester screening methods for Down's syndrome have limitations.
- There is uncertainty regarding the optimal screening approach for clinical practice.
- An integrated approach combining data from both trimesters is proposed.
Purpose of the Study:
- To develop and evaluate a novel integrated screening method for Down's syndrome.
- To compare the efficacy of the integrated test with existing screening strategies.
Main Methods:
- Utilized data from published studies on first and second-trimester screening methods.
- First-trimester screening involved serum pregnancy-associated plasma protein A and nuchal translucency measurements.
- Second-trimester screening included serum markers: alpha-fetoprotein, unconjugated estriol, human chorionic gonadotropin, and inhibin A.
Main Results:
- The integrated test achieved an 85% detection rate for Down's syndrome with a 0.9% false positive rate at a 1 in 120 risk cutoff.
- This offers a higher detection rate and substantially lower false positive rate compared to current tests (5-22%).
- Replacing the second-trimester triple test with the integrated test increased detection to 85% (from 69%) and reduced invasive procedures by 80%.
Conclusions:
- The integrated screening test demonstrates superior performance in detecting Down's syndrome.
- It achieves higher detection rates with significantly lower false positive rates than existing methods.
- This integrated approach offers a more effective and safer screening strategy for Down's syndrome.