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Study calls for end to age thresholds for prenatal genetic testing


US research in this week's issue of THE LANCET challenges the health policies common in many countries in relation to maternal age and prenatal testing for chromosomal abnormalities such as Down's syndrome. Authors of the research conclude that current evidence does not support the conventional view that the balance between health risks and cost make prenatal testing appropriate only for women aged 35 years or over.

Prenatal testing guidelines recommend offering amniocentesis or chorionic villus sampling (analysis of placenta cells) to women aged 35 years or older, or who have been found by screening to be at a similarly high risk of giving birth to an infant with Down's syndrome or another chromosomal abnormality. This threshold was chosen, in part, because 35 was the approximate age at which amniocentesis was cost-beneficial when testing guidelines were developed in the USA in the 1970s.

Miriam Kuppermann from the University of California, San Francisco, USA, and colleagues did a cost-utility analysis of chorionic villus sampling and amniocentesis compared with no invasive testing using data from previously published randomised trials, case registries, and a utility assessment of 534 diverse pregnant women aged 16-47 years. The investigators found prenatal diagnostic testing to be cost effective (less than $15,000 per quality-adjusted life year gained for each woman)-regardless of age or risk at the time of testing.

Dr. Kuppermann comments: "We found that cost-utility analysis does not support the current practice of reserving chorionic villus sampling and amniocentesis for women who are 35 or older, or who are at similarly high risk of carrying a fetus affected by a chromosomal abnormality. Instead, prenatal diagnostic testing should be offered to pregnant women irrespective of maternal age or risk, and guidelines should emphasise the important role of individual preference when making decisions about prenatal diagnostic testing."

In an accompanying Commentary (p 258), Stavros Petrou from the University of Oxford, UK, concludes: "A positive decision to offer prenatal diagnostic testing to all pregnant women may have broader consequences, for obstetric and other health services. In many cash-limited systems, there would be a knock-on effect of increased service provision and need for training on the availability of staff for other services. A single economic evaluation provides necessary but insufficient information about the appropriate level of service. Good evidence for decisions about effectiveness is growing (eg, the Cochrane Library), but choosing how to allocate resources between options requires additional evidence from well-conducted economic studies of a wider range of competing technologies at the margin of provision."


Contact: UCSF Public Information Representative Eve Harris: 415-885-7277; F) 415-476-2557; E):
Dr. Stavros Petrou, National Perinatal Epidemiology Unit, Institute of Health Sciences, University of Oxford, Old Road, Headington, OX3 7LF Oxford, UK; T) Press Office 44-0-186-528-0528; E):

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