In British Columbia, prenatal genetic screening is offered to all pregnant women to determine the chance of their baby being born with a birth defect like Down syndrome, which is the most common chromosomal abnormality to affect fetuses. In Canada, the condition occurs in around 15.8/10,000 births. A number of different prenatal screening strategies can be used to determine the risk of Down syndrome, from amniocentesis and chorionic villus sampling, to the relatively new blood test known as non-invasive prenatal testing (NIPT).

Data show that NIPT is more sensitive and specific for trisomy 21 – the most common form of Down syndrome – when compared to conventional screening techniques. This means NIPT could reduce the risk of false results that need to be confirmed by potentially harmful invasive tests.

Dr. Aslam Anis, CHÉOS Director

CHÉOS Director Dr. Aslam Anis and Scientist Dr. Wei Zhang conducted a cost-effectiveness analysis comparing three Down syndrome screening techniques: contingent NIPT (second-tier use following initial serum integrated prenatal screening); serum-only screening; and universal NIPT (first-tier use). Their findings have been published in the peer-reviewed, open access scientific journal, PLoS ONE.

When speaking to the rationale for the study, Dr. Aslam Anis explains ‘previous publications have highlighted the effectiveness of NIPT in Down syndrome detection; however, the cost-effectiveness of the different NIPT strategies was unclear.’ He adds, ‘to overcome the limitations of past studies, we chose to assess the cost-effectiveness of the two proposed NIPT strategies using a microsimulation decision-analytic model from the perspective of the publicly funded health care payer in British Columbia.’

The research revealed that, based on the current cost of NIPT in the province, contingent NIPT is more cost-effective than serum-only screening; there’s lower long-term cost, lower cost per case detected, and higher gain in quality-adjusted life-years (QALY). When comparing contingent with universal NIPT, the long-term cost, QALY gain, and number of Down syndrome cases detected were higher with universal NIPT. Despite this, owing to the willingness-to-pay threshold in Canada, universal NIPT is overall deemed less cost-effective than contingent screening in the majority of pregnancies.

‘Our results were very sensitive to the current cost of NIPT in British Columbia. If the cost of NIPT changed to $200 or less, universal first-tier NIPT could become more cost-effective than contingent NIPT,’ explained Dr. Anis.

The analysis concluded NIPT use is generally beneficial when screening for Down syndrome. However, at current provincial prices, it is more cost-effective to use NIPT as a second-tier screening method versus a first-tier test.