Limiting the use of invasive prenatal diagnostic testing (amniocentesis and chorionic villus sampling) to women aged 35 years and older was originally recommended because at 35 years the risk of a procedure-related miscarriage (0.5 to 1 percent) is about equal to the risk of giving birth to an infant affected by a chromosomal disorder such as Down syndrome. Current guidelines recommend offering noninvasive screening tests (maternal serum screening and/or ultrasound) to women younger than age 35 and reserving invasive diagnostic testing for women who are aged 35 or older (or have been found via screening to be at similarly elevated risk).
Findings from two recent studies, supported in part by the Agency for Healthcare Research and Quality (HS07373) and led by A. Eugene Washington, M.D., of the University of California, San Francisco, question this approach. The first study recommends that prenatal diagnostic testing be offered to all women, not just those deemed at increased risk. The second study concludes that prenatal diagnostic testing can be cost effective at any age or risk level. Both studies are discussed here.
Caughey, A.B., Washington, A.E., Gildengorin, V., and Kuppermann, M. (2004, March). "Assessment of demand for prenatal diagnostic testing using willingness to pay." Obstetrics & Gynecology 103, pp. 539-545.
About one-third of women younger than 35 in this study indicated an interest in undergoing invasive prenatal diagnostic testing and a willingness to pay for at least a portion of the costs. Because the benefit of invasive prenatal testing is primarily to improve quality of life of patients, the patient herself is the best one to determine whether the benefits from such testing outweigh the risks, according to the investigators. They surveyed a racially, ethnically, and socioeconomically diverse group of 447 women of varying ages to assess their desire to undergo and willingness to pay for invasive prenatal testing for fetal chromosomal disorders.
Overall, 49 percent of the women indicated an interest in undergoing invasive prenatal diagnostic testing. Women aged 35 years and older were more likely to desire testing than younger women (72 vs. 36 percent). Among women under 35 who desired testing, 31 percent indicated that they would be willing to pay the full price of $1,300, whereas 73 percent were willing to pay a portion of the cost. Women who were 35 or older and women who were willing to have an elective abortion of a fetus with Down syndrome were 3.3 and 2.8 times more likely, respectively, to want to undergo prenatal diagnostic testing, after controlling for income, race/ethnicity, and education.
Women who were 35 or older and women who had an income over $35,000 were 3.5 and 2.3 times, respectively, more willing to pay the full price of testing. The researchers conclude that guidelines on use of prenatal genetic testing should be expanded to offer testing to all women, not just those deemed at high risk of having a child with chromosomal abnormalities.
Harris, R.A., Washington, A.E., Nease, Jr., R.F., and Kuppermann, M. (2004, January). "Cost utility of prenatal diagnosis and the risk-based threshold." Lancet 363, pp. 276-282.
Prenatal diagnostic testing can be cost effective at any age or risk level, according to this study. The investigators did a cost-utility analysis of chorionic villus sampling and amniocentesis vs. no invasive testing. They used data from randomized trials, case registries, and a utility assessment (a woman's preference for certain outcomes) of 534 pregnant women aged 16 to 47 years. They calculated that in the United States, amniocentesis costs less than $15,000 per quality-adjusted life year (QALY) gained for women of all ages and risk levels compared with no diagnostic testing. This cost is lower than the $50,000 per QALY gained that is considered acceptable for health care interventions.
These results did not depend on maternal age or risk of Down syndrome-affected birth. The cost-utility ratio for any individual woman depended on her preferences for reassurance about the chromosomal status of her fetus and, to a lesser extent, for miscarriage. Thus, the researchers found no economic evidence to support the existing guidelines. In fact, they found no age threshold below which prenatal diagnosis would not be cost effective (greater than $50,000 per QALY gained). They recommend that instead of focusing on age and risk thresholds for offering or denying testing, guidelines should take into consideration women's preferences and emphasize ways to support informed choice by women of all ages and risk levels.
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