Cost-effectiveness of prenatal screening and diagnostic strategies for Down syndrome: A microsimulation modeling analysis

Wei Zhang,Julie Sou,Aslam H Anis,Tima Mohammadi,Badri Padhukasahasram

doi:10.1371/journal.pone.0225281

Abstract

ObjectivesDown syndrome (DS) is the most frequently occurring fetal chromosomal abnormality and different prenatal screening strategies are used for determining risk of DS worldwide. New non-invasive prenatal testing (NIPT), which uses cell-free fetal DNA in maternal blood can provide benefits due to its higher sensitivity and specificity in comparison to conventional screening tests. This study aimed to assess the cost-effectiveness of using population-level NIPT in fetal aneuploidy screening for DS.MethodsWe developed a microsimulation decision-analytic model to perform a probabilistic cost-effectiveness analysis (CEA) of prenatal screening and diagnostic strategies for DS. The model followed individual simulated pregnant women through the pregnancy pathway. The comparators were serum-only screening, contingent NIPT (i.e., NIPT as a second-tier screening test) and universal NIPT (i.e., NIPT as a first-tier screening test). To address uncertainty around the model parameters, the expected values of costs and quality-adjusted life-years (QALYs) in the base case and all scenario analyses were obtained through probabilistic analysis from a Monte Carlo simulation.ResultsBase case and scenario analyses were conducted by repeating the micro-simulation 1,000 times for a sample of 45,605 pregnant women per the population of British Columbia, Canada (N = 4.8 million). Preliminary results of the sequential CEAs showed that contingent NIPT was a dominant strategy compared to serum-only screening. Compared with contingent NIPT, universal NIPT at the current test price was not cost-effective with an incremental cost-effectiveness ratio over $100,000/QALY. Contingent NIPT also had the lowest cost per DS case detected among these three strategies.ConclusionIncluding NIPT in existing prenatal screening for DS is shown to be beneficial over conventional testing. However, at current prices, implementation of NIPT as a second-tier screening test is more cost-effective than deploying it as a universal test.

Highlights

Prenatal screening for Down syndrome (DS) and other chromosomal abnormalities such as trisomy 13 and 18 are offered in many countries worldwide [1,2]
Preliminary results of the sequential costeffectiveness analysis (CEA) showed that contingent non-invasive prenatal testing (NIPT) was a dominant strategy compared to serum-only screening
Including NIPT in existing prenatal screening for DS is shown to be beneficial over conventional testing

Summary

Introduction

Prenatal screening for Down syndrome (DS) (trisomy 21) and other chromosomal abnormalities such as trisomy 13 and 18 are offered in many countries worldwide [1,2]. DS is the most common chromosomal abnormality and the risk of an affected fetus increases with maternal age. Different prenatal screening options are available and include various maternal serum biomarkers and ultrasound measurement of nuchal translucency (NT). Non-invasive prenatal testing (NIPT), a relatively new blood test that measures the amount of cell-free fetal DNA circulating in maternal serum, has been demonstrated to have a greater sensitivity (>99%) and specificity ( 99%) for DS compared to conventional screening tests [10,11,12,13]. Due to improved test performance, NIPT greatly reduces the number of false positives that need to be confirmed by invasive tests and avoids the potential for procedure-related fetal loss

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