Health economic evaluation of five prenatal screening strategies for Down's syndrome

Abstract

Objective To investigate the cost-effectiveness and cost-benefit of five screening strategies for Down syndrome (DS) to optimize prenatal screening strategy. Methods A retrospective analysis was conducted in 26 803 gravidas, who underwent the second trimester maternal serum screening ( maternal serum α-fetoprotein and β-human chorionic gonadotropin) from 2002 to 2003, whom were classified into three groups according to the results of serum DS screening: high risk group (≥1/270), borderline risk group (≥1/1 000-<1/270) and elderly gravida group (age at expected date of confinement≥35 years old). TreeAge Pro 2011 sofware was used to set up the decision tree model for cost-effectiveness and cost-benefit analysis. Strategy 1: Maternal serum screening was carried out on all gravidas, and then prenatal diagnosis was performed for women in high risk group. Strategy 2: Non-invasive prenatal testing (NIPT) was carried out on all gravidas, and then prenatal diagnosis was offered for women with positive or suspected results. Strategy 3: NIPT was only carried out on gravidas of advanced maternal age and maternal serum screening was performed on the rest population. Gravidas with positive or suspected positive results in NIPT or classified into the high risk group underwent prenatal diagnosis. Strategy 4: Maternal serum screening was carried out on all gravidas. Those at high risk received prenatal diagnosis, while those at borderline risk underwent NIPT first and followed by prenatal diagnosis if positive or suspected positive NIPT results were identified. Strategy 5: Maternal serum screening was carried out on all gravidas. Those at high or borderline risk would undergo NIPT followed by prenatal diagnosis if they were positive or suspected positive for NIPT. Results (1) Among 26 803 gravidas, 1 244 were at high risk group (4.64%) with five having trisomy 21; 3 925 were at bordelrine risk (14.64%) with four having trisomy 21; 300 women were of advanced age (1.12%) with one having trisomy 21. (2) Cost-effectiveness analysis: the incremental cost-effectiveness ratios of strategy 3 and 4 were negative and that of strategy 1 was 0 with a cost-effectiveness ratio of 15 833 764.53. The incremental cost-effectiveness ratio of strategy 2 was 49 865 746.10, which was far greater than that of strategy 5 (63 049.56). The cost-effectiveness ratio of strategy 4 is 586 703.63, which was less than those of strategy 1,2 and 3 but higher than that of strategy 5. The average cost-effectiveness ratio of strategy 5 was the lowest (508 431.20) among these five strategies, which meant that for every diagnosis of DS, strategy 5 had the lowest cost (508 400 yuan). (3) Cost-benefit analysis: The benefits of strategy 4 and 5 were greater than their costs. Strategy 5 had the highest benefit-cost ratio, followed by strategy 4, 2, 3 and 1. (4) When other factors remained unchanged and only the acceptance rate of prenatal diagnosis was adjusted from 50% to 100%, strategy 1 had the least cost expectation, followed by strategy 3, 5, 4 and 2. When the cost of NIPT was below 82.4 yuan, the cost expectation of strategy 2 that performed on all gravidas was the lowest, while when it was between 82.4 and 1 827.2 yuan, the screening cost of strategy 5 was the lowest. Conclusions Strategy 5 has the best cost-effectiveness and cost-benefit. It would be the best screening strategy for DS, if the cost of NIPT is between 82.4-1 827.2 yuan. Key words: Down syndrome; Neonatal screening; Prenatal diagnosis; Costs and cost analysis; Cost-benefit analysis; High-throughput nucleotide sequencing