Down's syndrome risk estimates demonstrate considerable heterogeneity despite homogeneity of input

Reynolds, Tim; Ellis, Andy; Jones, Rick
November 2004
Annals of Clinical Biochemistry;Nov2004, Vol. 41 Issue 6, p464
Academic Journal
Background: Due to concerns about screening quality, Down's syndrome screening laboratories were surveyed to identify the range of variation in risk-calculation software. Methods: All UK Down's syndrome screening laboratories were sent the confidential survey via the National External Quality Assessment Scheme. This covered the software used, its origin, the risk calculation methodology and the Gaussian population parameters. Laboratories were also given multiples of the median (MoM) data from five representative cases and asked to calculate Down's syndrome risks on their systems. Results: Most parameter sets could be traced to published literature. The range of risk results for identical patient data was wide; the largest differences between lowest and highest risk for a test MoM set were: α-fetoprotein (AFP)+human chorionic gonadotrophin (hCG), 1:95 to 1:388 = 408%; AFP+hCG+urine estriol (UE3), 1:2011 to 1:7000 = 348%; AFP+free-β-hCG, 1:280 to 1:1681 = 600%; AFP+free-β-hCG+UE3, 1:340 to 1:13000 = 3823%. Two explanations for this variation – the prior age risk result (half-year correction) and the population parameters – are described. Conclusions: (a) All laboratories should apply half-year correction for maternal age risk calculation. (b) Triple-test parameter variations result in huge variation of risk estimates, and a single national risk threshold of 1 in 250 will be unlikely to improve screening equity unless attention is also paid to standardizing population parameters. Down's syndrome screening has been controversial since it was introduced, and the possibility that more central control (including listing acceptable population parameters) may be necessary to ensure comparability of results is certain to ensure that this controversy continues.


Related Articles

  • Estimation of Median in the Presence of Three Known Quartiles of an Auxiliary Variable. Singha, Housila P.; Shanmugamb, Ramalingam; Singhc, Sarjinder; Jong-Min Kim // Communications for Statistical Applications & Methods;2014, Vol. 21 Issue 5, p363 

    This paper has improved several ratio type estimators of the population median including their generalization in the presence of three known quartiles of an auxiliary variable. The properties of the improved estimators are discussed and applied. Both the empirical and simulation studies confirm...

  • Arterial Structure and Function in Mild Primary Hyperparathyroidism Is Not Directly Related to Parathyroid Hormone, Calcium, or Vitamin D. Ring, Margareta; Farahnak, Parastou; Gustavsson, Tomas; Nilsson, Inga-Lena; Eriksson, Maria J.; Caidahl, Kenneth // PLoS ONE;Jul2012, Vol. 7 Issue 7, p1 

    Objective: Elevated levels of calcium and parathyroid hormone (PTH), characteristics of primary hyperparathyroidism (PHPT), may be associated with cardiovascular morbidity and mortality in the general population. We evaluated the possible vascular effects of these risk factors in patients with...

  • Modeling and analysis of some methods of entomological data collection. Nedorezov, L. V. // Computational Ecology & Software;Jun2012, Vol. 2 Issue 2, p83 

    In current publication the stochastic model of individual migrations within the limits of closed domain and processes of data collections using in entomology are considered. The behavior of data variation with respect to changing of population size is analyzed. In particular, it was shown that...

  • Indiana's Pushing Forty: Latest Population Projections for Indiana Counties and Regions. Besl, John R.; Marcus, Morton J.; Gr�nbjerg, Kirsten A.; Park, Hun Myoung // Indiana Business Review;Summer2003, Vol. 78 Issue 2, p1 

    The article reports on latest population projections for Indiana counties and regions. New population projections released by the Indiana Business Research Center (IBRC) at Indiana University's Kelley School of Business portray big changes on the horizon in the size, geographic distribution, and...

  • Nonparametric Tests of Differences in Medians: Comparison of the Wilcoxon–Mann–Whitney and Robust Rank-Order Tests. Feltovich, Nick // Experimental Economics;Nov2003, Vol. 6 Issue 3, p273 

    The nonparametric Wilcoxon–Mann–Whitney test is commonly used by experimental economists for detecting differences in central tendency between two samples. This test is only theoretically appropriate under certain assumptions concerning the population distributions from which the...

  • The XperCount, a fast and cost-effective method for the enumeration of organisms in environmental media. Masson, S.; Lavigne, S.; Robitaille, V.; Andrews, C. // Journal of Xenobiotics;2013, Vol. 3 Issue 1s, p26 

    The article presents a study which examined the potential of the XperCount developed by XpertSea Solutions Inc. for reducing variability in population size estimation of live aquatic cultures. Topics discussed include the optoelectronic features of the equipment, measurement, and dynamic data...

  • Multistage Median Ranked Set Sampling for Estimating the Population Median. Aziz Jemain, Abdul; Al-Omari, Amer; Ibrahim, Kamarulzaman // Journal of Mathematics & Statistics;2007, Vol. 3 Issue 2, p58 

    We modify RSS to come up with new sampling method, namely, Multistage Median Ranked Set Sampling (MMRSS). The MMRSS was suggested for estimating the population median and to increase the efficiency of the estimator for specific value of the sample size. The MMRSS was compared to the Simple...

  • Selection of snap bean recombined inbred lines by using EGT and SSD. Vilela, Felipe Oliveira; do Amaral, Júnior, Antonio Teixeira; Freitas, Júnior, Silvério de Paiva; Viana, Alexandre Pio; Pereira, Messias Gonzaga; de Morais Silva, Marcelo Geraldo // Euphytica;Jan2009, Vol. 165 Issue 1, p21 

    With the objective of selecting superior recombinant lines of snap bean, four segregating F2 populations were selected by early generation testing and advanced by single seed descent. In a randomized complete block design with two replications within sets 120 F6:7 lines were obtained and...

  • Gen Kaynaklarinin ve BiyoçeÅŸitliliÄŸin Korunmasi Kapsaminda Yerli At Irklarinin Genetik Karakterizasyonu. Aksu, Soner; Aktopraklig&idot;l, Diğdem; Koban, Evren; Aslan, Özgür; Den&idot;zc&idot;, Melis; Balcioglu, Koray; Özdem&idot;r Bahadir, Aylin; Erdag, Berrin; Bagiş, Haydar; Arat, Sezen // Research Journal of Biological Sciences;2010, Vol. 5 Issue 1, p129 

    Nowadays, animal genetic resources are rapidly decreasing due to environmental and economic conditions. In order to protect genetic diversity that we have, the molecular characterization of domestic animal genetic resources and in vitro conservation studies have been initiated by the...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics