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Bestwick JP, Huttly WJ, Wald NJ. Evaluation of a proposed mixture model to specify the distributions of nuchal translucency measurements in antenatal screening for Down's syndrome. J Med Screen. 2010;17(1):13-8doi: 10.1258/jms.2010.009108.
Bestwick, J. P., Huttly, W. J., & Wald, N. J. (2010). Evaluation of a proposed mixture model to specify the distributions of nuchal translucency measurements in antenatal screening for Down's syndrome. Journal of medical screening, 17(1), 13-8. https://doi.org/10.1258/jms.2010.009108
Bestwick, J P, et al. "Evaluation of a proposed mixture model to specify the distributions of nuchal translucency measurements in antenatal screening for Down's syndrome." Journal of medical screening vol. 17,1 (2010): 13-8. doi: https://doi.org/10.1258/jms.2010.009108
Bestwick JP, Huttly WJ, Wald NJ. Evaluation of a proposed mixture model to specify the distributions of nuchal translucency measurements in antenatal screening for Down's syndrome. J Med Screen. 2010;17(1):13-8. doi: 10.1258/jms.2010.009108. PMID: 20356940; PMCID: PMC3104819.
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J Med Screen. 2010;17(1):13-8. doi: 10.1258/jms.2010.009108.

Evaluation of a proposed mixture model to specify the distributions of nuchal translucency measurements in antenatal screening for Down's syndrome.

Journal of medical screening

J P Bestwick, W J Huttly, N J Wald

Affiliations

  1. Wolfson Institute of Preventive Medicine, Barts and the London Queen Marys School of Medicine and Dentistry, Charterhouse Square, London EC1M 6BQ, UK. [email protected]

PMID: 20356940 PMCID: PMC3104819 DOI: 10.1258/jms.2010.009108

Abstract

OBJECTIVES: A mixture model of crown-rump length (CRL)-dependent and CRL-independent nuchal translucency (NT) measurements has been proposed for antenatal screening for Down's syndrome. We here compare the efficacy of the mixture model method with the standard method, which uses NT multiple of the median (MoM) values in a single distribution. Settings A routine antenatal screening programme for Down's syndrome comprising 104 affected and 22,284 unaffected pregnancies.

METHODS: The ability of NT to distinguish between affected and unaffected pregnancies was compared using the mixture model method and the standard MoM method by using published distribution parameters for the mixture model of NT and parameters derived from these for the standard MoM method. The accuracy of the two methods was compared for NT and maternal age by comparing the median estimated risk with the prevalence of Down's syndrome in different categories of estimated risk.

RESULTS: Using NT alone observed estimates of discrimination using the two methods are similar; at a 70% detection rate the false-positive rates were 12% using the mixture model method and 10% using the MoM method. Risk estimation was marginally (but not statistically significantly) more accurate using the standard MoM method.

CONCLUSIONS: The mixture model method offers no advantage over the standard MoM method in antenatal screening for Down's syndrome, is more complicated and less generalizable to other data-sets. The standard MoM method remains the method of choice.

References

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  2. J Med Screen. 2006;13(4):166-71 - PubMed
  3. Ultrasound Obstet Gynecol. 2008 Apr;31(4):376-83 - PubMed
  4. J Med Screen. 2010;17(1):8-12 - PubMed

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