Cost-effectiveness threshold of first-trimester Down syndrome maternal serum screening for the use of cell-free DNA as a second-tier screening test.

Abstract

We aimed to identify the most relevant cost-effectiveness threshold of first-trimester Down syndrome (DS) maternal serum screening (T21T1) for the use of cell-free DNA (cfDNA) as a second-tier test in the French context. A cost-effectiveness analysis was performed on 108,121 singleton pregnancies using a simulation model. The threshold of T21T1 screening was ranged from 1/51 to 1/1,000 in steps of 1/50. The most relevant threshold was based on cost-effectiveness ratio (CER; costs =direct medical costs after T21T1 screening/ effectiveness =number of DS cases identified). In the sample, 161cases of DS were identified. At the threshold of ≥1/50, 47.2% of total DS cases were diagnosed. In the simulation model, for a threshold ≥ 1/250, 73.9% of total DS cases were diagnosed, for ≥ 1/500, 78.8% and for ≥ 1/1,000, only two additional cases were diagnosed. The slope of the cost increase was slight from threshold ≥ 1/250 (978,634€), then steep up to 1/500 (1,966,576€) and increased exponentially to 1/1,000 (3,980,216€). The CER was 38,560 for a threshold ≥ 1/500. The most cost-effective threshold for cfDNA as a second-tier test seems to be ≥1/500. For higher thresholds, costs increase dramatically for only a few additional cases of DS identified.