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Age-standardisation when target setting and auditing performance of Down syndrome screening programmes
Howard Cuckle1, David Aitken, Sandra Goodburn
1Reproductive Epidemiology, University of Leeds, UK. h.s.cuckle@leeds.ac.uk
Prenatal Diagnosis
|November 27, 2004
Summary
This study introduces an age-standardized method for setting Down syndrome screening targets. This approach allows for accurate performance auditing by accounting for variations in maternal age distributions.
Area of Science:
- Prenatal diagnostics
- Maternal health
- Statistical modeling in healthcare
Background:
- Down syndrome screening programs face challenges in comparing performance due to differing maternal age distributions.
- Accurate auditing requires methods that account for demographic variations between screening centers.
Purpose of the Study:
- To develop and demonstrate an age-standardized methodology for setting Down syndrome screening targets.
- To enable valid performance auditing of screening programs by controlling for maternal age variations.
Main Methods:
- Utilized a Gaussian model of maternal age to define a reference population.
- Applied statistical modeling to determine target detection and false-positive rates using the reference population.
- Calculated audited rates as a weighted average across age groups, correcting for viability bias.
Main Results:
- Maternal age distribution approximated a Gaussian model (mean 27, SD 5.5 years).
- Target detection rates ranged from 59-68% and false-positive rates from 4.2-7.3% based on cut-offs.
- Audited detection rates varied +/- 10% from target; false-positive rates were consistently better than target.
Conclusions:
- Age-standardization is crucial for improving the quality and comparability of Down syndrome screening programs.
- This method facilitates valid comparisons between different screening initiatives by addressing intrinsic demographic differences.