Cost utility of prenatal diagnosis and the risk-based threshold

Prenatal testing guidelines recommend offering amniocentesis or chorionic villus sampling 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. We aimed to assess the economic validity of thresholds based on age or risk for offering invasive prenatal diagnosis.

We did a cost-utility analysis of chorionic villus sampling and amniocentesis versus no invasive testing using data from randomised trials, case registries, and a utility assessment of 534 diverse pregnant women aged 16-47 years.

In the USA, compared with no diagnostic testing, amniocentesis costs less than US15000 dollars per quality-adjusted life year gained for women of all ages and risk levels. The results do not depend on maternal age or risk of Down's syndrome-affected birth. The cost-utility ratio for any individual woman depends on her preferences for reassurance about the chromosomal status of her fetus, and, to a lesser extent, for miscarriage.

Prenatal diagnostic testing can be cost effective at any age or risk level. Current guidelines should be changed to offer testing to all pregnant women, not just those whose risk of carrying an affected fetus exceeds a specified threshold.