Combining Multiple Markers Into a Risk Based Screen

As a marker for risk of Down syndrome, MSAFP by itself measured solely for the purpose of estimating the risk of Down syndrome would not be powerful enough to be justified. However, because MSAFP is widely used for ONTD screening, use of its modest additional information about the risk of Down syndrome is easily justified. Screening for Down syndrome also benefited from screening for ONTD in that the concept of the MoM had already been developed for ONTD screening (see Using the MoM to Adjust...