Reproductive behaviour following spontaneous loss of pregnancy after prenatal diagnosis

Cost utility of prenatal diagnosis and the risk-based threshold

BACKGROUND

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.

METHODS

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.

FINDINGS

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.

INTERPRETATION

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.

Decision analysis of prenatal testing for chromosomal disorders: what do the preferences of pregnant women tell us?

Current guidelines recommend offering invasive testing for chromosomal disorders only to women who are aged 35 or older, or who are at similarly elevated risk (as determined by maternal serum and/or ultrasonographic screening). We conducted a decision analysis, using preference scores obtained from pregnant women, to determine whether current guidelines maximize the health-related quality of life of these women. If only miscarriage and chromosomal abnormalities are considered, the expected value of testing exceeds that of not testing for women 30 years of age or older. However, if a comprehensive range of relevant testing outcomes is considered, testing offers a higher expected value than not testing, regardless of age. Furthermore, patient preferences for specific testing outcomes play a much more substantial role in determining the course of action with the highest expected value than does the probability of any of the possible testing outcomes. The current age- and risk-based guideline for prenatal diagnosis does not maximize expected value and fails to appropriately consider individual patient preferences. For counseling purposes, how an individual values the presence and timing of fetal chromosomal information should be carefully understood.