Empirical validation of risk screening for Down's syndrome

Area of Science:

• Prenatal diagnostics
• Biochemical screening
• Genetics

Background:

• Antenatal screening for Down's syndrome is crucial for informed reproductive decisions.
• Previous methods relied heavily on maternal age, with limited accuracy.
• Multiple marker screening tests have been developed to improve detection rates.

Purpose of the Study:

• To validate the accuracy of individual risk estimates generated by antenatal serum screening for Down's syndrome.
• To compare the predicted risks with observed prevalence for both triple and quadruple screening tests.

Main Methods:

• Utilized data from approximately 100,000 pregnant women screened between 1989 and 1995.
• Employed the triple test (AFP, uE3, hCG) and the quadruple test (AFP, uE3, free beta-hCG, free alpha-hCG) with maternal age.
• Grouped participants by predicted Down's syndrome risk and compared mean predicted risk with observed prevalence.

Main Results:

• Demonstrated close agreement between predicted term risk and birth prevalence for both screening methods.
• The quadruple test showed high accuracy, with predicted risks of 1 in 3.3 (highest risk) and 1 in 3000 (lowest risk) aligning with observed prevalences of 1 in 2.6 and 1 in 2300, respectively.

Conclusions:

• Risk estimates derived from multiple marker screening for Down's syndrome are accurate.
• The validation method is simple and provides an effective empirical check on screening performance.
• These findings support the clinical utility of current Down syndrome screening protocols.