New Down Syndrome DNA Test Effective and Economical

Karyn Hede

February 01, 2013

A new type of noninvasive prenatal test for Down syndrome is more effective and less costly than traditional prenatal screening methods, according to new study published online January 28 in the Journal of Maternal-Fetal & Neonatal Medicine.

For pregnant women older than 35 years, screening for chromosomal abnormalities such as Down syndrome has become routine. Until recently, such testing involved invasive procedures such as chorionic villus sampling and amniocentesis, which are accurate but carry a risk for procedure-related miscarriage. Within the last few years, noninvasive testing for Down syndrome, caused by trisomy (a third copy) of chromosome 21, has become available. Tests that look for blood serum markers in conjunction with ultrasound have a 5% false-positive rate and fail to detect up to 20% of cases. More recently, massively parallel gene sequencing has made it possible to identify and sequence fetal DNA in maternal blood with detection rates nearly as good as the more invasive procedures, but without the attendant risk to the fetus.

Ken Song, MD, chief executive officer, Ariosa Diagnostics Inc, San Jose, California, and colleagues scanned the published literature and reviewed abstracts from meetings, data from Medicare, and data from Ariosa Diagnostics, as well as its competitors, to compare outcomes and costs of the various screening options.

Using an analytic model, the research team concluded that noninvasive prenatal testing (NIPT) provided more accurate detection with fewer fetal losses at a lower cost compared with both first-trimester serum protein screening with ultrasound (FTS) and integrated screening, which included testing of additional blood protein markers. The analysis showed that NIPT detected 28% to 43% more trisomy 21 cases compared with the other methods examined and that NIPT reduced invasive procedures by more than 95%, resulting in lower overall costs to the healthcare system. Specifically, the authors conclude that the total screening strategy costs of NIPT was $382,844,191 less than FTS and $516,534,401 less than integrated screening. However, the analysis was based on a theoretical group of women giving birth in the United States and hinged on assumptions about screening performance and cost.

"To me, the crux of this paper is that NIPT detects more cases of Down syndrome with fewer procedure-related losses than other strategies," said George Macones, MD, 
director of maternal-fetal medicine and ultrasound at Washington University, St. Louis, Missouri. "I think that information alone is enough to justify the use of the test in high-risk women. I would also add that the cost of these tests will go down as the technology advances."

The American Congress of Obstetrics and Gynecology and the Society for Maternal-Fetal Medicine recommend NIPT for pregnant women aged 35 years and older, those with increased trisomy risk resulting from family or individual history, and those women at high risk for trisomy based on other kinds of prenatal screening, such as ultrasound.

One coauthor is a clinical advisor for Ariosa Diagnostics. Dr. Song and one coauthor are paid employees of Ariosa Diagnostics. Dr. Macones has disclosed no relevant financial relationships.

J Matern Fetal Neonatal Med. Published online January 28, 2013. Full text