Fetal Down syndrome screening models for developing countries; Part II: Cost-benefit analysis

Abstract

BackgroundTo identify the most cost-beneficial model as a national policy of screening and diagnosis of fetal Down syndrome (DS) in developing countries.MethodsCost-benefit analysis (CBA) was performed based on the effectiveness and probabilities derived from a large prospective study on MSS (maternal serum screening) among Thai population. Various models including maternal age alone, STS (second trimester screen), I-S (independent screen: first or second trimester screen depending on the time of first visit), C-S (contingent serum screen) plus STS, maternal age with NIPS (non-invasive prenatal test), STS alone with NIPS, I-S with NIPS, C-S plus STS with NIPS, and Universal NIPS were compared.ResultsI-S with NIPS as a secondary screening was most cost-beneficial (Benefit/Cost ratio 4.28). Cost-benefit is directly related to the costs of NIPS.ConclusionIn addition to simplicity and feasibility, I-S with expensive NIPS as a secondary screening is the most cost-beneficial method for low resource settings and should be included in universal healthcare coverage as a national policy. This study could be a model for developing countries or a guideline for international health organizations to help low resource countries, probably leading to a paradigm shift in prenatal diagnosis of fetal DS in the developing world.

Ethnic-specific reference range affects the efficacy of quadruple test as a universal screening for Down syndrome in a developing country

“…Thus, maternal weight adjustment for serum calculation has an important role as this will vary among nations [ 7 , 20 ]. Moreover, our study and previous studies have shown that race and ethnic factors have an important effect on serum concentrations both in DS and normal fetuses throughout the gestational period [ 7 , 10 – 12 , 20 ]. Another study from our institution reported the same evidence from first trimester serum screening for DS [ 21 ].…”

“…This was in contrast to a study by Tana et al [ 20 ], which was also done in Thai pregnant women but reported the detection rate of triple serum markers, and which found that using the ethnic-specific factor resulted in a remarkable decrease in the false positive rate although the detection rate was still the same. Many studies in Asian populations have found that using ethnic factors had an impact on the results of quadruple serum screening [ 7 , 10 , 25 – 28 ]. Our study and evidence from previous studies support the idea that using an ethnic-specific reference range has a significant impact on the diagnostic performance in each population [ 29 – 31 ].…”

“…Although there is a more accurate cell-free fetal DNA test, due to the high cost of this test, the quadruple test is still being used for fetal DS screening, especially in low-resource countries [4][5][6]. Many studies have confirmed the screening efficacy of this test in developing countries with an acceptable detection rate for DS screening [7][8][9][10]. Because this test is convenient and not costly, it is appropriate for pregnant women who present later than the first trimester and for health care services that lack expertise in ultrasound to measure nuchal translucency or evaluate the second trimester sonomarkers of DS.…”

“…Many studies have reported that using an incorrect ethnic factor with different reference ranges of serum markers leads to higher numbers of false positives. For example, using the Western European descent factor (WF), which is programmed into most automatic testing machines, to calculate DS risk in Thailand was found to have false positive rates as high as 13% in the triple test compared with an average false positive rate of 7.8% when using the ethnic-specific Thai factor (TF) in Thailand [ 7 ]. However, there are limited data regarding the efficacy and false positive rate in the Thai population for the quadruple test, which the National Thai Health Policy has selected as the universal DS screening test for pregnant Thai women.…”

Cost-Benefit Analysis of Down Syndrome Screening in Iran

“…In the social perspective, all direct and indirect costs and benefits are taken into account, regardless of who incurs or benefits from it (24). It is recommended to perform CBA method from the societal perspective because both taking care of a DS child and the loss of a healthy fetus following diagnostic tests are all societal burden (25).…”