UK NHS pilot study on cell-free DNA testing in screening for fetal trisomies: factors affecting uptake

Abstract

Objective: This study reports on the clinical implementation of cell-free DNA (cfDNA) testing, contingent on the results of the combined test, in screening for fetal trisomies 21, 18 and 13 in two UK National Health Service hospitals. Women with a combined-test risk of ≥ 1:100 (high risk) were offered the options of chorionic villus sampling (CVS), cfDNA testing or no further testing and those with a risk of 1:101 to 1:2500 (intermediate risk) were offered cfDNA or no further testing. The objective of the study was to examine the factors affecting patient decisions concerning their options.

Methods: Combined screening was performed in 6651 singleton pregnancies in which the risk for trisomies was high in 260 (3.9%), intermediate in 2017 (30.3%) and low in 4374 (65.8%). Logistic regression analysis was used to determine which factors among maternal characteristics, fetal nuchal translucency thickness (NT) and risk for trisomies were significant predictors of opting for CVS in the high-risk group and opting for cfDNA testing in the intermediate-risk group.

Results: In the high-risk group, 104 (40.0%) women opted for CVS; predictors for CVS were increasing fetal NT and increasing risk for trisomies, while the predictor against CVS was being of Afro-Caribbean racial origin (r = 0.366). In the intermediate-risk group, 1850 (91.7%) women opted for cfDNA testing; predictors for cfDNA testing were increasing maternal age, increasing risk for trisomies and university education, while predictors against cfDNA testing were being of Afro-Caribbean racial origin, smoking and being parous (r = 0.105).

Conclusions: This study has identified factors that can influence the decision of women undergoing combined screening in favor of or against CVS and in favor of or against cfDNA testing.

Keywords: cell-free DNA; chorionic villus sampling; decision making; first trimester; first-trimester screening; prenatal diagnosis.