Model-based analysis of costs and outcomes of non-invasive prenatal testing for Down's syndrome using cell free fetal DNA in the UK National Health Service

Clinical strategy study on prenatal screening and diagnostic model for Down syndrome

Exploring efficient and easily implementable prenatal screening strategies aims at birth defect prevention and control. However, there have been limited economic evaluations of non-invasive prenatal screening (NIPS) strategies in China. Furthermore, these studies were predominantly confined to local or geographically proximate provinces and lacked universality and representativeness. This study assesses the health economics of current prenatal screening strategies and NIPS as first-line screening programs, analyzing their efficacy to determine an optimal strategy. From the perspective of health economics, cost-effectiveness, cost-benefit, and single-factor sensitivity were conducted for five different screening strategies using a decision tree model. Among pregnant women aged < 35 years who underwent only one screening for foetal Down syndrome (DS), the detection rate, false positive rate and positive predictive value of NIPS for foetuses with DS were superior to those of the other four serological screening methods. Although applying NIPS as first-line screening method yields the highest efficacy and benefits, it currently lacks cost-effectiveness when compared to serological screening and sequential NIPS screening strategies.

Impact of Structural Differences on the Modeled Cost-Effectiveness of Noninvasive Prenatal Testing

BACKGROUND

Noninvasive prenatal testing (NIPT) was developed to improve the accuracy of prenatal screening to detect chromosomal abnormalities. Published economic analyses have yielded different incremental cost-effective ratios (ICERs), leading to conclusions of NIPT being dominant, cost-effective, and cost-ineffective. These analyses have used different model structures, and the extent to which these structural variations have contributed to differences in ICERs is unclear.

AIM

To assess the impact of different model structures on the cost-effectiveness of NIPT for the detection of trisomy 21 (T21; Down syndrome).

METHODS

A systematic review identified economic models comparing NIPT to conventional screening. The key variations in identified model structures were the number of health states and modeling approach. New models with different structures were developed in TreeAge and populated with consistent parameters to enable a comparison of the impact of selected structural variations on results.

RESULTS

The review identified 34 economic models. Based on these findings, demonstration models were developed: 1) a decision tree with 3 health states, 2) a decision tree with 5 health states, 3) a microsimulation with 3 health states, and 4) a microsimulation with 5 health states. The base-case ICER from each model was 1) USD$34,474 (2023)/quality-adjusted life-year (QALY), 2) USD$14,990 (2023)/QALY, (3) USD$54,983 (2023)/QALY, and (4) NIPT was dominated.

CONCLUSION

Model-structuring choices can have a large impact on the ICER and conclusions regarding cost-effectiveness, which may inadvertently affect policy decisions to support or not support funding for NIPT. The use of reference models could improve international consistency in health policy decision making for prenatal screening.

HIGHLIGHTS

NIPT is a clinical area in which a variety of modeling approaches have been published, with wide variation in reported cost-effectiveness.This study shows that when broader contextual factors are held constant, varying the model structure yields results that range from NIPT being less effective and more expensive than conventional screening (i.e., NIPT was dominated) through to NIPT being more effective and more expensive than conventional screening with an ICER of USD$54,983 (2023)/QALY.Model-structuring choices may inadvertently affect policy decisions to support or not support funding of NIPT. Reference models could improve international consistency in health policy decision making for prenatal screening.

Women's preferences for NIPT as a first-line test in England and France: Challenges for genetic counseling practices

Non-invasive prenatal testing (NIPT) is provided in the private and public sectors worldwide as a first- or second-tier test. In England and France, NIPT is fully funded and offered as a contingent strategy with different probability cut-offs (1:150 and 1:1000). These different approaches to define the target population for NIPT have implications for how women experience their antenatal care. The paper explores and compares the perceptions and difficulties of women in England and France who took NIPT as a second-tier screening test. It is based on a semi-structured qualitative interview study with 17 women in England and France conducted between September 2021 and May 2022. The interviews were cross-analyzed using thematic analysis. Our findings show that most women express a preference for the offer of NIPT as a first-line screening test. Some issues with the contingent model, related to the access to information and termination of pregnancy (TOP), the disparities of NIPT uptake, and risks of generating anxiety with combined first-trimester screening (cFTS), could be addressed by a universal strategy for T21, T13, and T18. Nevertheless, this strategy could present some challenges for genetic counseling due to: women's understanding and expectations of NIPT; adequate information and counseling about the scope and limits of NIPT; concerns about the routinization of NIPT in the first-line offer; limitations and uncertainties associated with the provision of expanded NIPT in France; the remaining importance of other screening tests; and associated costs.

COMBINED FIRST TRIMESTER SCREENING FOR FETAL DOWN SYNDROME AT THE SPLIT UNIVERSITY HOSPITAL CENTER: A SEVEN-YEAR EXPERIENCE

The aim of this study was to present the results and to explore the success of combined screening at the Split University Hospital Center. A cross-sectional retrospective study was performed, including all pregnant women who underwent combined screening at the Split University Hospital Center from 2011 to 2017. Data were collected from the hospital archives. During the research period, a total of 6898 pregnant women underwent combined screening. With the high risk cut-off value set at 1:250, the sensitivity of combined screening was 81.0% and specificity 96.8% (AUC 0.929, 95% CI 0.859-1.000; p<0.001). The mean value of a priori risk of Down syndrome based on age was higher than the one calculated by combined screening (1:487.57 vs. 1:13216.9; p<0.001). The number of women who were a priori at a high risk of Down syndrome was significantly higher than the number of those at a high risk based on combined screening results (1457 vs. 239; p<0.001). With the increase in women's age, a statistically significant increase was detected in the mean value of a priori risk of Down syndrome, as well as in the risk based on combined screening results (p<0.001). Combined screening detected a high risk in 8.09% (118/1457) of pregnant women a priori at a high risk of Down syndrome, as well as in 2.22% (121/5441) of pregnant women a priori at a low risk of it. Thus, combined screening placed 121 pregnant women a priori at a low risk in the high-risk group. Down syndrome was subsequently confirmed in 17 (14.05%) women. Analysis of the combined screening results confirmed the validity of using the said fetal Down syndrome screening method in the study population of pregnant women.

Issues associated with possible implementation of Non-Invasive Prenatal Testing (NIPT) in first-tier screening: A rapid scoping review

In recent years, as the implementation and use of Non-Invasive Prenatal Testing (NIPT) have increased, the cost of the test has been decreasing. The cost of NIPT is expected to fall further in the upcoming years. As a result of the decreasing cost of NIPT, many jurisdictions may change their prenatal screening policies toward abandoning serum-based screening and instead, implement and support NIPT as the first-tier screening for all women. There are several concerns in replacing first-trimester screening with NIPT. In this scoping review, we aimed to map the existing knowledge about possible issues in the systematic implementation of NIPT as the primary method of first-tier screening and to assess if any jurisdiction has altered its policy and discontinued serum-based prenatal screening in exchange for NIPT. The Medline database (Ovid) and Google Scholar was searched and all the studies discussing, investigating, or reporting on the systematic implementation of NIPT as the primary method of first-tier screening were included. All the studies went through a two-stage screening process and included full-text articles were reviewed. We did not find any articles indicating a country or region that replaced traditional prenatal screening by NIPT. The included articles were charted, and the data about the possible issues in the systematic implementation of NIPT as the primary method of first-tier screening are summarized narratively and presented in tables in four categories. The findings of this scoping review may be informative for stakeholders and policymakers regarding recent changes in NIPT implementation policies around the world and may aid with developing policy for NIPT implementation with a broader perspective.

Global Trends in Research on Cell-Free Nucleic Acids in Obstetrics and Gynecology during 2017–2021

Objectives. The objectives of this study were to identify global trends in research on cell-free deoxyribonucleic acid (cfDNA) from a bibliometric perspective and provide researchers with new research hotspots. Methods. In all, we extracted 5038 pieces of literature from PubMed and 527 articles from the Web of Science Core Collection (WoSCC) database related to cfDNA published from 1 January 2017 to 31 December 2021. For PubMed literature, we employed co-word, biclustering, and strategic diagram analysis to describe the trends in research on cfDNA in the said five years. Then, we used VOSviewer analysis for the WoSCC database to display the trends in research on cfDNA in obstetrics and gynecology during 2017–2021. Results. Strategy diagram analysis of 95 major Medical Subject Headings terms extracted from 5038 pieces of literature indicated that cfDNA sequence analysis for non-invasive prenatal and genetic testing and its application in the fields of neoplasm genetics and diagnosis is a newly emerging immature theme of cfDNA. VOSviewer analysis of 527 articles showed the global trends in research on cfDNA in obstetrics and gynecology, for example, in terms of most influential authors, institutions, countries, journals, and five research hotspots: (1) cfDNA application in prenatal screening and prenatal diagnosis, (2) cfDNA application in assisted reproductive technology, (3) cfDNA application in pre-eclampsia, DNA methylation, etc., (4) cfDNA application in placental dysfunction and fetal growth restriction, and (5) cfDNA application in fetal chromosomal abnormalities (fetal aneuploidy). Conclusions. Comprehensive visual analysis provides information regarding authors, organizations, countries/regions, journals, research hotspots, and emerging topics in the field of cfDNA for obstetrics and gynecology research. This comprehensive study could make it easier to find a partner for project development and build a network of knowledge on this emerging topic.

Critical appraisal of droplet digital polymerase chain reaction application for noninvasive prenatal testing

Maternal-fetal medicine (FM) is currently a highly demanding branch and is gaining importance as increasing number of genetic disorders rise in incidence. Prenatal testing helps to detect such abnormalities that could affect the health status of the developing fetus like birth defects or genetic disorders. Considering the rising trend of genetic disorders, there is a need for a highly sensitive way of noninvasive prenatal testing (NIPT) that may reduce the incidence of unnecessary invasive procedures and iatrogenic fetal loss. The concept of NIPT for screening of genetic disorders is continuously evolving over the last two decades and multiple techniques have come up to utilize this in the field of FM. The crucial factor which decides the accuracy of NIPS is cell free fetal DNA (cffDNA) that is present in extremely low fraction (10%-15%) in the maternal plasma. Among the available methods, the next generation sequencing (NGS) is considered as the gold standard. However, the higher cost diminishes its utility in low-resource settings. Droplet digital Polymerase chain reaction (ddPCR), a type of digital PCR is a novel technique that is frugal, equally sensitive, less labor intensive, less time-consuming and plain algorithm dependent method for detecting cffDNA fraction. Considering these impressive attributes of ddPCR, we decided to critically review the existing literature on ddPCR for NIPT whilst highlighting the clinical utility, challenges and its advantages over NGS.

Optimising Exome Prenatal Sequencing Services (EXPRESS): a study protocol to evaluate rapid prenatal exome sequencing in the NHS Genomic Medicine Service

Background

Prenatal exome sequencing (ES) for the diagnosis of fetal anomalies was implemented nationally in England in October 2020 by the NHS Genomic Medicine Service (GMS). is the GMS is based around seven regional Genomic Laboratory Hubs (GLHs). Prenatal ES has the potential to significantly improve NHS prenatal diagnostic services by increasing genetic diagnoses and informing prenatal decision-making. Prenatal ES has not previously been offered routinely in a national healthcare system and there are gaps in knowledge and guidance.

Methods

Our mixed-methods evaluation commenced in October 2020, aligning with the start date of the NHS prenatal ES service . Study design draws on a framework developed in previous studies of major system innovation. There are five interrelated workstreams. Workstream-1 will use interviews and surveys with professionals, non-participant observations and documentary analysis to produce in-depth case studies across all GLHs. Data collection at multiple time points will track changes over time. In Workstream-2 qualitative interviews with parents offered prenatal ES will explore experiences and establish information and support needs. Workstream-3 will analyse data from all prenatal ES tests for nine-months to establish service outcomes (e.g. diagnostic yield, referral rates, referral sources). Comparisons between GLHs will identify factors (individual or service-related) associated with any variation in outcomes. Workstream-4 will identify and analyse practical ethical problems. Requirements for an effective ethics framework for an optimal and equitable service will be determined. Workstream-5 will assess costs and cost-effectiveness of prenatal ES versus standard tests and evaluate costs of implementing an optimal prenatal ES care pathway. Integration of findings will determine key features of an optimal care pathway from a service delivery, parent and professional perspective.

Discussion

The proposed formative and summative evaluation will inform the evolving prenatal ES service to ensure equity of access, high standards of care and benefits for parents across England.

Health economic evaluation of noninvasive prenatal testing and serum screening for down syndrome

Background

Down syndrome (DS), also known as trisomy 21 (T21), is the most common genetic disorder associated with intellectual disability. There are two methods commonly used for prenatal testing of DS: serum screening (SS) for biomarkers in maternal serum and noninvasive prenatal testing (NIPT) for aneuploidy by cell-free DNA (cfDNA) in maternal plasma. However, cost-effectiveness analyses of these two methods are mostly based on data derived from simulations with various models, with theoretical values calculated. In this study, we statistically analyzed clinical DS screening data and pregnancy outcomes during the follow-up of pregnant women in Zhuhai City, China. The economics of the two mainstream prenatal DS screening methods was evaluated from a public health perspective.

Methods

A retrospective analysis was performed on the data of 17,363 pregnant women who received SS and NIPT during gestation in Zhuhai from 2018 to 2019, and a cost-effectiveness analysis was performed with four screening strategies. In strategy I, all pregnant women received SS, and those with T21 risk ≥1/270 had invasive prenatal diagnosis (IPD). In strategy II, all pregnant women received SS, those with T21 risk ≥ 1/270 had IPD, and those with 1/270 > T21 risk ≥ 1/1,000 had NIPT; then, women at high risk based on NIPT also had IPD. In strategy III, all pregnant women received SS, and those with T21 risk ≥1,000 had NIPT; then, women at high risk based on NIPT results had IPD. In strategy IV, all pregnant women received NIPT and those at high risk based on NIPT results had IPD. Finally, to assess the cost and effectiveness of DS screening, the total costs were calculated as the sum of screening and diagnosis as well as the direct and indirect economic burden during the average life cycle of DS patients.

Results

A total of 22 of the 17,363 (1/789) pregnant women had DS, of which only one woman was over 35 years of age. SS detected 1,024 cases at high risk of T21 (≥1/270), 8 cases were true positive, with a positive predictive value of 0.78% and a detection rate of 36.4%. NIPT detected 27 cases at high risk of T21 (Z ≥ 3) and 22 cases of DS, with a positive predictive value of 81.5% and a detection rate of 100%. Strategy I had the largest total cost of 65.54 million CNY, strategy II and III had similar total costs of 40 million CNY, and strategy IV had the lowest total cost of 14.91 million CNY. By comparison, the screening strategy with NIPT alone had the highest health economic value for DS.

Conclusions

SS was greatly affected by nuchal translucency and the accuracy of gestational age measured by ultrasonography. Unstandardized ultrasonography was an important reason for the low DS detection rate with SS. The influence of interfering factors on NIPT was much lower than in SS. NIPT can be used as an alternative to SS and as a primary screening strategy of prenatal DS screening for secondary prevention and control of birth defects. NIPT greatly decreased the frequency of IPD and the miscarriages associated with IPD, saved the limited medical and health resources, and greatly increased DS detection rate. Therefore, NIPT has great social and economic benefits.

Biochemical Serum Markers Influencing Maternal Age Risk for Down's Syndrome in Quadruple Marker

Objective: Maternal age is the primary risk factor associated with Down syndrome (DS) in the fetus. Biochemical serum markers in maternal screenings have improved DS detection rates in prenatal screenings. However, there is a dilemma regarding which age group should undergo preliminary noninvasive screening before undergoing invasive diagnostic procedures. Based on recommendations, all pregnancies are at risk of chromosomal abnormalities. While all women should be offered screenings, those over 35 are mainly offered an invasive diagnostic procedure, and serum screening tests are of little benefit for this age group. This study evaluated the maternal serum screening population and the significance of the final screen positivity rate in the risk group aged above 35 years.

Method: An observational retrospective study was conducted on a cohort of pregnancies in the second trimester (14-20 weeks and 6 days of gestation) over a period of one year. The quadruple test consisted of serum alpha-fetoprotein (AFP), free beta hCG, unconjugated estriol e3 (Ue3), and inhibin-A. The risk for DS was calculated using software with corrections for ethnicity, smoking, weight, and age. We compared the age risk for DS with the biochemical risk. Statistical analysis was done using McNemar’s test to test the proportion of screen-positive (SP) cases between the two calculation methods, i.e., age alone versus final risk calculation with biomarkers.

Results: The proportion of SP cases from age risk and final risk were 56.3% and 12.6%, respectively. The computed McNemar’s chi-square test statistic was 97.959 (p < 0.001), which showed a significant reduction in SP cases when biomarkers were added to screen for trisomy 21 women aged >35 years.

Conclusion: The age risk of DS increased with increasing maternal age. Notably, the final biochemical risk in this population was significantly lower. Consequently, we proposed that a noninvasive serum screening be used to screen all age groups to rule out negative screen cases before subjecting them to invasive procedures.

Machine learning-based evaluation of application value of the USM combined with NIPT in the diagnosis of fetal chromosomal abnormalities

OBJECTIVE

To explore the soft ultrasound marker (USM) combined with non-invasive prenatal testing (NIPT) in diagnosing fetal chromosomal abnormalities based on machine learning and data mining techniques.

METHODS

To analyze the data of ultrasonic examination from 856 cases with high-risk single pregnancy during early and middle pregnancy stage. NIPT was applied in 642 patients. All 856 patients accepted amniocentesis and chromosome karyotype analysis to determine the efficacy of USM, Down's syndrome screening, and NIPT in detecting fetal chromosomal abnormalities.

RESULTS

Among the 856 fetuses, 129 fetuses (15.07%) with single positive USM and 36 fetuses (4.21%) with two or more positive USM. There were 81 fetuses (9.46%) with chromosomal abnormalities. In the group with multiple USM, chromosomal abnormalities were found in 36.11% of them. It was higher than the group without USM, which was 6.22% (P < 0.01), and the group with just a single USM (19.38%, P < 0.05). The sensitivity, specificity and accuracy were 96.72%, 98.45% and 98.29% when the combination of USM, Down's syndrome screening and NIPT was used to diagnose fetal chromosomal abnormalities further evaluating the accuracy and effectiveness of the above diagnostic criteria and methods with mainstream Classifiers based evaluation indicators of accuracy, f1 score, AUC.

CONCLUSIONS

The combination of USM, Down's syndrome screening and NIPT is valuable for the diagnosis of fetal chromosomal abnormalities.

Introducing the non-invasive prenatal testing for detection of Down syndrome in China: a cost-effectiveness analysis

OBJECTIVE

This study aimed to compare the health economic value of a non-invasive prenatal testing (NIPT) strategy against a second-trimester triple screening (STS) strategy for the detection of Down syndrome based on real-world data from China.

DESIGN

A decision-analytical model was developed to compare the cost-effectiveness of five strategies from a societal perspective. Cost and probability input data were obtained from the real-world surveys and published sources.

SETTING

China.

PARTICIPANTS

Women with a singleton pregnancy.

INTERVENTIONS

The five strategies for screening were: (A) maternal age with STS (no NIPT); (B) STS plus NIPT screening; (C) age-STS plus NIPT screening (the currently referral strategy in China); (D) maternal age with NIPT screening and (E) universal NIPT screening.

MAIN OUTCOME MEASURES

Incremental cost-effectiveness ratios (ICERs) per additional Down syndrome case terminated, univariate and probabilistic sensitivity analysis and cost-effectiveness acceptability curves were obtained.

RESULTS

Strategy A detected the least number of Down syndrome cases. Compared with the cheapest Strategy B, Strategy D had the lowest ICER (incremental cost, US$98 944.85 per additional Down syndrome case detected). Strategy D had the highest probability of being cost-effective at the willingness-to-pay level between US$110 000.00 and US$535 000.00 per additional Down syndrome case averted. Strategy E would not be cost-effective unless the unit cost of the NIPT could be decreased to US$60.50.

CONCLUSION

Introducing NIPT screening strategies was beneficial over the use of STS strategy alone. Evaluating maternal age in combination with the NIPT screening strategy performs better than China's currently referral strategy in terms of cost-effectiveness and safety. Lowering the price of NIPT and optimising payment methods are effective measures to promote universal NIPT strategies in China.

Towards a better understanding of preimplantation genetic screening and cumulative reproductive outcome: transfer strategy, diagnostic accuracy and cost-effectiveness

A decision model was constructed to compare genetic testing and not testing, for the transfer of all suitable embryos, one at a time, from a cycle with up to ten embryos, until a first live birth was achieved or there were no more embryos available (a full cycle). Two strategies were investigated: (i) a fresh transfer with subsequent serial warmed cryopreserved embryo replacement, and (ii) freeze-all prior to serial embryo replacement. Sensitivity analyses were performed to assess the effect of embryo warming survival and diagnostic accuracy on cumulative rates. Cost-effectiveness was assessed using the incremental cost-effectiveness ratio for a live birth event, and a clinical miscarriage avoided. Reproductive outcome probabilities were obtained from published prospective non-selection studies, and costs from websites and publications.

Given 100% embryo warming survival and no false abnormal genetic test results, the live birth rate for a full cycle was the same with and without testing for both transfer strategies. Compared to not testing, it was theoretically possible for testing to be favoured for live birth only for the fresh and frozen transfer strategy, where more than one embryo was available, and dependent on the efficiency of warming survival and the positive predictive value of the test; however, this was unlikely to be cost-effective from a society perspective without a substantial reduction in genetic testing costs. For both transfer strategies, when more than one embryo was available, testing was more likely to achieve a live birth event following the first attempt with fewer attempts required overall. Testing was likely to be effective to avoid a clinical miscarriage but also to be expensive from a society perspective compared to the cost of dilation and curettage.

Uptake of fetal aneuploidy screening after the introduction of the non-invasive prenatal test: A national population-based register study

INTRODUCTION

The introduction of the non-invasive prenatal test (NIPT) has shifted the prenatal screening landscape. Countries are exploring ways to integrate NIPT in their national prenatal screening programs, either as a first- or second-tier test. This study aimed to describe how the uptake of fetal aneuploidy screening changed after the introduction of NIPT as a second-tier and as a first-tier test within the national prenatal screening program of the Netherlands.

MATERIAL AND METHODS

A population-based register study in the Netherlands, recording uptake of fetal aneuploidy screening. Data from all pregnant women choosing to have the first-trimester combined test (FCT) or first-tier NIPT between January 2007 and March 2019 were retrospectively collected using national registration systems. Uptake percentages for fetal aneuploidy screening (FCT and NIPT) were calculated and stratified by region and maternal age. Statistical significance was determined using trend analysis and chi-squared tests.

RESULTS

Between 2007 and 2013 FCT uptake increased from 14.8% to 29.5% (P = .004). In April 2014 NIPT was introduced as a second-tier test for high-risk women after FCT (TRIDENT-1 study). FCT uptake rose from 29.5% in 2013 to 34.2% in 2015 (P < .0001). After the introduction of NIPT as a first-tier test for all women in April 2017 (TRIDENT-2 study), FCT uptake declined significantly from 35.8% in 2016 to 2.6% in 2018 (P < .0001). NIPT uptake increased to 43.4% in 2018. Regionally, NIPT uptake ranged from 31.8% to 67.9%. Total uptake (FCT and NIPT) between 2007 and 2018 increased significantly from 14.8% to 45.9% (P < .0001). However, total uptake stabilized at 46% for both years of TRIDENT-2 (April 2017-March 2019).

CONCLUSIONS

An increase in total fetal aneuploidy screening uptake up to 45.9% was observed after the introduction of NIPT. Uptake appears to have stabilized within a year after introducing first-tier NIPT.

Introducing cell-free DNA noninvasive testing in a Down syndrome public health screening program: a budget impact analysis

BACKGROUND

Non-invasive prenatal testing (NIPT) using cell-free fetal DNA in maternal plasma is a high accurate test for prenatal screening for Down syndrome. Although it has been reported to be cost effective as a contingent test, evidence about its budget impact is lacking.

OBJECTIVE

To evaluate, using computer simulations, the budget impact of implementing NIPT as a contingent test in the Quebec Program of screening for Trisomy 21.

METHODS

A semi-Markov analytic model built to simulate the budget impact of implementing NIPT into the current Quebec Trisomy 21 public Prenatal Screening, Serum Integrated prenatal screening (SIPS). Comparisons were made for a virtual population similar to that of expected Quebec pregnant women in 2015 in terms of size and age. Data input parameters were retrieved from a thorough literature search and in government databases, especially data from Quebec Program of screening for Trisomy 21. The 2015-2016 fiscal year budget impact was estimated from the Quebec healthcare system perspective and was expressed as the difference in the overall costs between the two alternatives (SIPS minus SPS + NIPT).

RESULTS

Our study found that, at a baseline cost for NIPT of CAD$ 795, NIPT as a second-tier test offered to high-risk women identified by current screening program (SIPS + NIPT) may be affordable for Quebec health care system. Compared to the current screening program, it would be implemented at a neutral cost, considering a modest annual savings of $ 80,432 (95% CI $ 79, $ 874-$ 81,462). Results were sensitive to the NIPT costs and the uptake-rate of invasive diagnostic tests.

CONCLUSION

Introducing NIPT as a contingent test in the Quebec Trisomy 21 screening program is an affordable strategy compared to the current practice. Further research is needed to confirm if our results can be reproduced in other healthcare jurisdictions.

Eliciting women's preference for prenatal testing in China: a discrete choice experiment

Background

Pregnancy tests can be used for the early diagnosis of fetal problems and can prevent abnormal birth in pregnancies. Yet, testing preferences among Chinese women are poorly investigated.

Methods

We developed a Discrete Choice Experiment with 5 attributes: test procedure, detection rate, miscarriage rate, time to wait for result, and test cost. By studying the choices that the women make in the hypothetical scenarios and comparing the attributes and levels, we can analyze the women’s preference of prenatal testing in China.

Results

Ninety-two women completed the study. Respondents considered the test procedure as the most important attribute, followed by detection rate, miscarriage rate, wait time for result, and test cost, respectively. The estimated preference weight for the non-invasive procedure was 0.928 (P < 0.0001). All other attributes being equal, the odds of choosing a non-invasive testing procedure over an invasive one was 2.53 (95% confidence interval, 2.42–2.64; P < 0.001). Participants were willing to pay up to RMB$28,810 (approximately US$4610) for a non-invasive test, RMB$6061(US$970) to reduce the miscarriage rate by 1% and up to RMB$3356 (US$537) to increase the detection rate by 1%. Compared to other DCE (Discrete Choice Experiment) studies regarding Down’s syndrome screening, women in our study place relatively less emphasis on test safety.

Conclusions

The present study has shown that Chinese women place more emphasis on detection rate than test safety. Chinese women place great preference on noninvasive prenatal testing, which indicate a popular need of incorporating noninvasive prenatal testing into the health insurance coverage in China. This study provided valuable evidence for the decision makers in the Chinese government.

A Retrospective Analysis Of Different Contingent Screening Models For Fetal Down Syndrome In Southwestern China

To discuss combinations of traditional screening and noninvasive prenatal screening (NIPS) and to compare which traditional screening is the most suitable first-line screening approach to NIPS, pregnant women were recruited in this retrospective observational study. Pregnant women underwent one of four traditional screening tests. The 9 contingent models were combined by high risk cut-offs of 1:50, 1:100, 1:270 and intermediate risk cut-offs of 1:1000, 1:1500, 1:2000. We analyzed cost and performance of various screening models with contingent screening of different risk cut-offs. Compared with other screening tests, combined first-trimester screening (CFTS) had the lowest proportion of high risk (≥1:270) with the highest detection rate (DR) (78.79%) and the lowest proportion of intermediate risk (1:271~1:1000). When intermediate risk was 1:51 ~1:1500, CFTS as first-line screening had the lowest cost with DR of 93.94%. Other screening tests as the first-line screening with intermediate risk of 1:51~1:1000 had the lowest cost, there DR were 90.91%, 84.62%, 91.67%, respectively. Our study demonstrated if only one traditional screening was allowed to screen pregnant women, CFTS was recommended as the first choice. According to local health and economic conditions, adopting appropriate traditional screening with suitable cut-offs as first-line screening will contributed to a cost-effective screening model.

Missed Down Syndrome Cases after First Trimester False-Negative Screening-Lessons to be Learned

Background and Objectives: Here, we performed a descriptive analysis of Down syndrome (DS) cases that were misdiagnosed and/or false-negative diagnosed after first trimester traditional screening via risk evaluation using ultrasound, biochemical markers, and different software programs. Our objective was to demonstrate the clear need to improve the application of prenatal DS screening programs using standardized ultrasound measurements, accurate pregnancy dating, analytical immunoassay performance, and properly selected medians. Materials and Methods: We performed a database search for the period 2010–2015 to analyze DS cases that were false-negative diagnosed after the first trimester of pregnancy, before the introduction of cell free fetal DNA-based tests by Romanian laboratories in 2015. First-trimester screening was performed using two software programs for prenatal DS risk calculation: Astraia and Prisca. The rationale for using both software programs was to assess the full risk using the maternal age combined test (based on nuchal translucency thickness, nasal bone, ductus venosus flow, tricuspid flow, free beta-human chorionic gonadotropin level, and serum pregnancy-associated plasma protein-A) and, in some cases, the triple test. Results: We identified seven DS cases that exhibited low risk for trisomy 21, and 6540 cases with a low risk for trisomy 21 and euploid fetus in the first trimester. Using Astraia software, 14 cases were diagnosed, and three cases were missed after risk calculation. Using Prisca software, four cases were missed. Additionally, one neonate had a missed prenatal diagnosis of atrio-ventricular canal defect. Conclusion: In Romania, the evaluation of DS risk depends on patient choice (without knowing the accuracy of the utilized tests) and on the operators’ skills. Both Astraia and Prisca software were developed by experts, who can prove their performance in DS screening. However, even in an ideal situation, false-negative results are possible. The application of first and second-trimester combined screening based on biochemical markers could be improved by the implementation of standardized protocols, professional guidelines for test application, and audit control.

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

Objectives

Down 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.

Methods

We 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.

Results

Base 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.

Conclusion

Including 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.

The role of information provision in economic evaluations of non-invasive prenatal testing: a systematic review

BACKGROUND

Technological progress has led to changes in the antenatal screening programmes, most significantly the introduction of non-invasive prenatal testing (NIPT). The availability of a new type of testing changes the type of information that the parent(s) require before, during and after screening to mitigate anxiety about the testing process and results.

OBJECTIVES

To identify the extent to which economic evaluations of NIPT have accounted for the need to provide information alongside testing and the associated costs and health outcomes of information provision.

METHODS

A systematic review of economic evaluations of NIPTs (up to February 2018) was conducted. Medline, Embase, CINAHL and PsychINFO were searched using an electronic search strategy combining a published economic search filter (from NHS economic evaluations database) with terms related to NIPT and screening-related technologies. Data were extracted using the Consolidated Health Economic Evaluation Reporting Standards framework and the results were summarised as part of a narrative synthesis.

RESULTS

A total of 12 economic evaluations were identified. The majority of evaluations (n = 10; 83.3%) involved cost effectiveness analysis. Only four studies (33.3%) included the cost of providing information about NIPT in their economic evaluation. Two studies considered the impact of test results on parents' quality of life by allowing utility decrements for different outcomes. Some studies suggested that the challenges of valuing information prohibited their inclusion in an economic evaluation.

CONCLUSION

Economic evaluations of NIPTs need to account for the costs and outcomes associated with information provision, otherwise estimates of cost effectiveness may prove inaccurate.

Nicht invasive Pränataldiagnostik mittels molekulargenetischer Tests (NIPT) zur Erkennung der Trisomien 13, 18 und 21

Hintergrund

Molekulargenetische Tests (NIPT) auf Trisomie sind längst Teil der nicht invasiven Pränataldiagnostik (NIPD). In Deutschland wird derzeit geprüft, ob und für wen diese Tests von den gesetzlichen Krankenkassen künftig bezahlt werden sollen.

Fragestellung

(I) Diagnostische Eigenschaften der NIPT zur Entdeckung der Trisomien 13, 18 und 21 und (II) hypothetische Berechnung der möglichen Anwendung der NIPT in verschiedenen Gruppen.

Methoden

(I) Systematische Recherche nach Primärliteratur und systematischen Übersichten in MEDLINE und vier weiteren Datenbanken. Einschlusskriterien: Studien mit schwangeren Frauen, Indextest: NIPT mittels molekulargenetischer Analyse von cffDNA im mütterlichen Blut zur Bestimmung des Trisomie-Risikos; Referenztest: zytogenetische Diagnostik oder postnatale klinische Untersuchung. (II) Orientierende Recherche. Hypothetische Berechnungen für (1) alle schwangeren Frauen nach aktuellem Vorgehen ohne NIPT am Beispiel von Ersttrimesterscreening (ETS), (2) Anwendung bei schwangeren Frauen mit erhöhtem Risiko, z. B. nach vorgeschaltetem auffälligem ETS und (3) NIPT in einer Population mit und ohne erhöhtes Risiko für eine Trisomie.

Ergebnisse

Bei 22 eingeschlossenen Studien lagen die Sensitivität und die Spezifität zur Erkennung der Trisomie 21 bei 99,13 % (95 %-KI: [97,39 %; 99,72 %]) und 99,95 % (95 %-KI: [99,88 %; 99,98 %]). Der mögliche Einfluss von Testversagern blieb bei den Berechnungen unberücksichtigt, womit die Sensitivität oder die Spezifität der NIPT möglicherweise überschätzt wurde. Für die Erkennung der Trisomien 13 und 18 konnte jeweils die Sensitivität nicht robust geschätzt werden.

Diskussion

Bei Frauen mit erhöhtem Risiko können NIPT die Zahl der invasiven Tests und damit der testbedingten Fehlgeburten vermutlich verringern.

A proof-of-concept study on the effects of low total cfDNA content and solutions to increase the NIPT trisomy 21 detection rate

Background

Non‐invasive prenatal testing (NIPT) is routinely used in clinical practice for fetal trisomy screening, but low total cfDNA content and low fetal fraction (LFF) are two factors that affect the detection rate. Samples with low total cfDNA or LFF usually end up with “no‐call” results, followed by the blood redraw and re‐testing, which is inconvenient for pregnant women and clinicians.

Methods

We created mock trisomy 21 (T21) samples to investigate the effects of low total cfDNA with low LFF and possible solutions to increase their detection rate.

Results

Samples with low total cfDNA resulted in the decreased unique reads number and increased duplication rate. Abnormal correlations between library concentration and raw reads number and the coverage fluctuation value, ZsdNorm, were also discovered, suggesting that low total cfDNA could lead to the overestimation of the library concentration. Additionally, a non‐reference‐based derivative value method (DV method) was evaluated and the data demonstrated that the detection sensitivity of trisomy 21 was increased from 33.33% (6/18) to 94.44% (17/18) in samples with 5% fetal fraction comparing with the z‐score approach, whereas for LFF (3.5%) group, the performance was raised from 0% to 35.29% (6/17).

Conclusion

Low total cfDNA has significant impacts on NIPT performance by altering sequencing quality. The non‐reference‐based DV method could increase the T21 detection rate in samples with limited cfDNA content and 5% fetal fraction, but it was not as effective for those with LFF.

Clinical validation of a novel automated cell-free DNA screening assay for trisomies 21, 13, and 18 in maternal plasma

Objective

To evaluate clinical performance of a new automated cell‐free (cf)DNA assay in maternal plasma screening for trisomies 21, 18, and 13, and to determine fetal sex.

Method

Maternal plasma samples from 1200 singleton pregnancies were analyzed with a new non–sequencing cfDNA method, which is based on imaging and counting specific chromosome targets. Reference outcomes were determined by either cytogenetic testing, of amniotic fluid or chorionic villi, or clinical examination of neonates.

Results

The samples examined included 158 fetal aneuploidies. Sensitivity was 100% (112/112) for trisomy 21, 89% (32/36) for trisomy 18, and 100% (10/10) for trisomy 13. The respective specificities were 100%, 99.5%, and 99.9%. There were five first pass failures (0.4%), all in unaffected pregnancies. Sex classification was performed on 979 of the samples and 99.6% (975/979) provided a concordant result.

Conclusion

The new automated cfDNA assay has high sensitivity and specificity for trisomies 21, 18, and 13 and accurate classification of fetal sex, while maintaining a low failure rate. The study demonstrated that cfDNA testing can be simplified and automated to reduce cost and thereby enabling wider population‐based screening.

What is already known about this topic?

Maternal plasma cell‐free (cf)DNA analysis with next-generation sequencing has a high sensitivity and specificity for fetal trisomy 21 and other common autosomal trisomies.

A new amplification-free, nonsequencing, and targeted cfDNA assay has been developed.

Proof‐of‐principle analysis found the new assay has promising results in screening for trisomy 21.

What does this study add?

The new assay has high sensitivity and specificity for trisomies 21, 18, and 13 in singleton pregnancies.

It can accurately determine fetal sex.

It is suitable for use in biochemical screening laboratories since it is highly automated and does not require specialized personnel.

No. 348-Joint SOGC-CCMG Guideline: Update on Prenatal Screening for Fetal Aneuploidy, Fetal Anomalies, and Adverse Pregnancy Outcomes

OBJECTIVE

To review the available prenatal screening options in light of the recent technical advances and to provide an update of previous guidelines in the field of prenatal screening.

INTENDED USERS

Health care providers involved in prenatal screening, including general practitioners, obstetricians, midwives, maternal fetal medicine specialists, geneticists, and radiologists.

TARGET POPULATION

All pregnant women receiving counselling and providing informed consent for prenatal screening.

EVIDENCE

Published literature was retrieved through searches of Medline, PubMed, and the Cochrane Library in and prior to March 2016 using an appropriate controlled vocabulary (prenatal diagnosis, amniocentesis, chorionic villi sampling, non-invasive prenatal screening) and key words (prenatal screening, prenatal genetic counselling). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies written in English and published from January 1985 to May 2016. Searches were updated on a regular basis and incorporated in the guideline. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical speciality societies.

GUIDELINE UPDATE

Evidence will be reviewed 5 years after publication to determine whether all or part of the guideline should be updated. However, if important new evidence is published prior to the 5-year cycle, the review process may be accelerated for a more rapid update of some recommendations.

Cost-Effectiveness Analysis of Non-invasive Prenatal Testing for Down Syndrome in China

OBJECTIVES

There is little evidence in China regarding the cost-effectiveness of non-invasive prenatal testing (NIPT) for Down syndrome (DS). This study aims to evaluate the cost-effectiveness of NIPT and provide evidence to inform decision-making.

METHODS

To determine the cost-effectiveness of NIPT for DS, a decision-analytic model was developed using the TreeAge Pro software from a societal perspective in a simulated cohort of 10 000 pregnant women. Main indicators were based on field surveys from sampled hospitals in four locations in China and a literature review.

RESULTS

The conventional maternal serum screening (CMSS) strategy, contingent screening strategy (NIPT delivered to high risk pregnant women after CMSS), and universal screening strategy could prevent 3.02, 7.53, and 9.97 DS births, respectively. NIPT would decrease unnecessary invasive procedures, resulting in fewer procedure-related miscarriages. The cost-effectiveness ratio of the contingent screening strategy was the lowest. When compared with the CMSS strategy, the incremental cost per DS birth averted by the contingent screening strategy and universal screening strategy were USD 20,160 and 352,388, respectively. One-way sensitivity analysis showed that, if the cost of NIPT could be decreased to USD 76.92, the cost-effectiveness ratio of the universal screening strategy would be lower than the CMSS strategy.

CONCLUSIONS

Although NIPT has the merits of greater effectiveness and safety, CMSS is unlikely to be replaced by NIPT at this time because of NIPT's higher cost. Contingent screening may be an appropriate strategy to balance the effectiveness and cost factors of the new genetic testing technology.

Preferences for aspects of antenatal and newborn screening: a systematic review

BACKGROUND

Many countries offer screening programmes to unborn and newborn babies (antenatal and newborn screening) to identify those at risk of certain conditions to aid earlier diagnosis and treatment. Technological advances have stimulated the development of screening programmes to include more conditions, subsequently changing the information required and potential benefit-risk trade-offs driving participation. Quantifying preferences for screening programmes can provide programme commissioners with data to understand potential demand, the drivers of this demand, information provision required to support the programmes and the extent to which preferences differ in a population. This study aimed to identify published studies eliciting preferences for antenatal and newborn screening programmes and provide an overview of key methods and findings.

METHODS

A systematic search of electronic databases for key terms identified eligible studies (discrete choice experiments (DCEs) or best-worst scaling (BWS) studies related to antenatal/newborn testing/screening published between 1990 and October 2018). Data were systematically extracted, tabulated and summarised in a narrative review.

RESULTS

A total of 19 studies using a DCE or BWS to elicit preferences for antenatal (n = 15; 79%) and newborn screening (n = 4; 21%) programmes were identified. Most of the studies were conducted in Europe (n = 12; 63%) but there were some examples from North America (n = 2; 11%) and Australia (n = 2; 11%). Attributes most commonly included were accuracy of screening (n = 15; 79%) and when screening occurred (n = 13; 68%). Other commonly occurring attributes included information content (n = 11; 58%) and risk of miscarriage (n = 10; 53%). Pregnant women (n = 11; 58%) and healthcare professionals (n = 11; 58%) were the most common study samples. Ten studies (53%) compared preferences across different respondents. Two studies (11%) made comparisons between countries. The most popular analytical model was a standard conditional logit model (n = 11; 58%) and one study investigated preference heterogeneity with latent class analysis.

CONCLUSION

There is an existing literature identifying stated preferences for antenatal and newborn screening but the incorporation of more sophisticated design and analytical methods to investigate preference heterogeneity could extend the relevance of the findings to inform commissioning of new screening programmes.

The consequences of implementing non-invasive prenatal testing with cell-free foetal DNA for the detection of Down syndrome in the Spanish National Health Service: a cost-effectiveness analysis

BACKGROUND

DNA-based non-invasive prenatal testing (NIPT) using maternal blood constitutes an emerging technology for the detection of Down syndrome (DS). The aim of the study was to conduct a cost-effectiveness analysis to evaluate the economic costs and health implications of the introduction of NIPT based on cell-free foetal DNA analysis through different screening strategies for the detection of DS.

METHODS

An analytical short-term decision model was developed, from the payer´s perspective (Spanish National Health Service). The main outcome measure was the number of DS cases detected. Secondary measures included associated miscarriages, women undergoing current screening, women undergoing NIPT, positive NIPT and invasive procedures performed. The study setting was the Spanish National Health Service. Three strategies were compared: (a) first- and second-trimester screening (current screening); (b) NIPT as contingent testing; and (c) NIPT as first-line testing. Modelling was based on a hypothetical cohort of 100,000 Spanish pregnant women. Population data were obtained from the database of the Basque Antenatal Screening Programme. Deterministic sensitivity analyses were performed to assess variations in the cost of NIPT, screening risk cut-off, screening uptake-rate and rate of failure of NIPT.

RESULTS

NIPT as contingent testing (strategy b) led to fewer miscarriages following invasive procedures and a slight reduction in the number of DS cases detected compared to current screening. However, lowering the screening cut-off to ≥ 1:500 would improve the overall effectiveness of NIPT as contingent testing, increasing the number of DS cases detected and decreasing foetal losses as compared to the current screening, despite there would be an extra-cost of 3.5%. When NIPT was used as first-line testing (strategy c), the screening would be more effective but also more expensive, with incremental cost-effectiveness ratios (ICERs) per additional case of DS detected of €1,299,763 and €1,232,763, compared with strategies a and b, respectively. Results were sensitive to the different parameters considered in the analysis.

CONCLUSIONS

Both, as first-line testing and as contingent testing when screening cut-off was lowered ≥ 1:500, NIPT would lead to more favourable outcomes as compared to the current screening (both in terms of DS cases detected and miscarriages avoided), but at a greater cost.

Update in non-invasive prenatal testing

Non-invasive prenatal testing (NIPT) has revolutionized the approach to prenatal diagnosis and, to date, it is the most superior screening method for the common autosomal aneuploidies, mostly trisomy 21. This screening is having a significant population-wide impact on the uptake of conventional screening and diagnostic testing. In recent years, emerging genomic technologies, largely based around next generation sequencing, have expanded the analyses to the sub-chromosomal aneuploidies. However, further clinical validation studies are needed to better characterize this technology. These tests bring advantage through providing a higher diagnostic yield, without risks of miscarriage than previously available diagnostic test, but also raise the question of harms related to an increase in uncertain and unknown results. In view of the revolution brought about by the NIPT, numerous scientific societies have published recommendations regarding the appropriate application of cell-free DNA screening in pregnancy. In this review, we discuss the progress that has been made to date in NIPT.

Cost-effectiveness of cell-free DNA in maternal blood testing for prenatal detection of trisomy 21, 18 and 13: a systematic review

The aim of this paper was to conduct a systematic review of the cost-effectiveness of the analysis of cell-free DNA in maternal blood, often called the non-invasive prenatal test (NIPT), in the prenatal screening of trisomy in chromosomes 21, 18 and 13. MEDLINE, MEDLINE in process, EMBASE, and Cochrane Library were searched in April 2017. We selected: (1) economic evaluations that estimated the costs and detected cases of trisomy 21, 18 or 13; (2) comparisons of prenatal screening with NIPT (universal or contingent strategies) and the usual screening without NIPT, (3) in pregnant women with any risk of foetal anomalies. Studies were reviewed by two researchers. Data were extracted, the methodological quality was assessed and a narrative synthesis was prepared. In total, 12 studies were included, four of them performed in Europe. Three studies evaluated NIPT as a contingent test, three studies evaluated a universal NIPT, and six studies evaluated both. The results are heterogeneous, especially for the contingent NIPT where the results range from NIPT being dominant to a dominated strategy. Universal NIPT was found to be more effective but also costlier than the usual screening, with very high incremental cost-effectiveness ratios. One advantage of screening with NIPT is lower invasive procedure-related foetal losses than with usual screening. In conclusion, the cost-effectiveness of contingent NIPT is uncertain according to several studies, while the universal NIPT is not cost-effective currently.

Clinical and Economic Impact of Adopting Noninvasive Prenatal Testing as a Primary Screening Method for Fetal Aneuploidies in the General Pregnancy Population

OBJECTIVE

To evaluate the clinical and economic impact of adopting noninvasive prenatal testing (NIPT) using circulating cell-free DNA as a first-line screening method for trisomy 21, 18, and 13 in the general pregnancy population.

METHODS

A decision-analytical model was developed to assess the impact of adopting NIPT as a primary screening test compared to conventional screening methods. The model takes the Belgium perspective and includes only the direct medical cost of screening, diagnosis, and procedure-related complications. NIPT costs are EUR 260. Clinical outcomes and the cost per trisomy detected were assessed. Sensitivity analysis measured the impact of NIPT false-positive rate (FPR) on modelled results.

RESULTS

The cost per trisomy detected was EUR 63,016 for conventional screening versus EUR 66,633 for NIPT, with a difference of EUR 3,617. NIPT reduced unnecessary invasive tests by 94.8%, decreased procedure-related miscarriages by 90.8%, and increased trisomies detected by 29.1%. Increasing the FPR of NIPT (from < 0.01 to 1.0%) increased the average number of invasive procedures required to diagnose a trisomy from 2.2 to 4.5, respectively.

CONCLUSION

NIPT first-line screening at a reasonable cost is cost-effective and provides better clinical outcomes. However, modelled results are dependent on the adoption of an NIPT with a low FPR.

Prenatal diagnostic testing and atypical chromosome abnormalities following combined first-trimester screening: implications for contingent models of non-invasive prenatal testing

OBJECTIVES

To investigate by means of a population-based analysis of a cohort of women who underwent combined first-trimester screening (CFTS), changes in uptake of invasive prenatal diagnosis according to risk of trisomy 21 (T21) on CFTS, and prevalence and methods for ascertainment of atypical chromosome abnormalities.

METHODS

This was a retrospective cohort study using state-wide prenatal datasets from Victoria, Australia. A three-step approach was taken to analyze the data: (1) linkage of records between serum screening and diagnostic results; (2) comparison of rates of diagnostic testing according to CFTS T21 risk result category in a 2014-2015 cohort with those of a historical 2002-2004 cohort; (3) detailed analysis of atypical abnormalities in the 2014-2015 group according to CFTS T21 risk result, individual serum analyte level and other indications for invasive diagnostic testing.

RESULTS

In 2014-2015, there were 100 418 CFTS results issued for 146 776 births (68.4%). The overall prevalence of atypical chromosome abnormalities in the entire CFTS cohort was 0.10% and was highest in those with CFTS T21 risk > 1 in 10 (4.6%), or serum analyte levels < 0.2 multiples of the median (MoM) (6.9% for pregnancy-associated plasma protein-A (PAPP-A) and 5.2% for beta-human chorionic gonadotropin (β-hCG)). Almost half (49.2%) of women with PAPP-A < 0.2 MoM had a risk for T21 on CFTS of less than 1 in 100. The majority (55%) of atypical abnormalities occurred in women with CFTS T21 risk below 1 in 300, and were most commonly detected on ultrasound examination (47.1%).

CONCLUSION

Concerns regarding missed diagnoses of atypical chromosome abnormalities when non-invasive prenatal testing is offered after a result of high risk on CFTS can be mitigated if invasive diagnostic testing is offered to those women with CFTS T21 risk of > 1 in 100, serum PAPP-A or β-hCG < 0.2 MoM, or ultrasound-detected abnormality. This has implications for contingent models of screening. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Cell-free DNA noninvasive prenatal screening for aneuploidy versus conventional screening: A systematic review of economic evaluations

Although noninvasive prenatal testing (NIPT) for aneuploidies using cell-free fetal DNA in maternal blood has been reported to have a high accuracy, only little evidence about its cost-effectiveness is available. We systematically reviewed and assessed quality of economic evaluation studies published between January 1, 2009 and January 1, 2016 where NIPT was compared to the current screening practices consisting of biochemical markers with or without nuchal translucency (NT) and/or maternal age. We included 16 studies and we found that, at current level of NIPT prices, contingent NIPT provide the best value for money, especially for publicly funded screening programs. NIPT as first-line test was found not cost-effective in the majority of studies. The NIPT unit cost, the risk cut-offs for current screening practice, the screening uptake rates (first- and second-line screening) as well as the costs and uptake rates of invasive diagnostic screening were the most common uncertain variables. The overall quality of included studies was fair. Considering a possible drop in prices and an ongoing NIPT expansion to include other chromosomes abnormalities other than T21, T18, T13 and sex chromosomes aneuploidies, future research are needed to examine the potential cost-effectiveness of implementing NIPT as first-line test.

Recent developments in genetics and medically assisted reproduction: from research to clinical applications

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Recent developments in genetics and medically-assisted reproduction: from research to clinical applications†‡

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively-parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Challenges in non-invasive prenatal screening for sub-chromosomal copy number variations using cell-free DNA

Non-invasive prenatal screening (NIPS) has revolutionized the approach to prenatal fetal aneuploidy screening. Many commercial providers now offer analyses for sub-chromosomal copy number variations (CNVs). Here, we review the use of NIPS in the context of screening for microdeletions and microduplications, issues surrounding the choice of disorders tested for, and the advantages and disadvantages associated with the inclusion of microdeletions to current NIPS. Several studies have claimed benefits; however, we suggest that microdeletions have not demonstrated a low enough false positive rate to be deemed practical or ethically acceptable, especially considering their low positive predictive values. Because a positive NIPS result should be confirmed using diagnostic techniques, and false positive rates are as high as 90% for some microdeletions, diagnostic testing seems preferable when the goal is to maximize the detection of microdeletion or microduplication syndromes.

Cell-Free DNA-Based Non-invasive Prenatal Screening for Common Aneuploidies in a Canadian Province: A Cost-Effectiveness Analysis

OBJECTIVE

Yearly, 450 000 pregnant Canadians are eligible for voluntary prenatal screening for trisomy 21. Different screening strategies select approximately 4% of women for invasive fetal chromosome testing. Non-invasive prenatal testing (NIPT) using maternal blood cell-free DNA could reduce those invasive procedures but is expensive. This study evaluated the cost-effectiveness of NIPT strategies compared with conventional strategies.

METHODS

This study used a decision analytic model to estimate the cost-effectiveness of 13 prenatal screening strategies for fetal aneuploidies: six frequently used strategies, universal NIPT, and six strategies incorporating NIPT as a second-tier test. The study considered a virtual cohort of pregnant women of similar size and age as women in Quebec. Model data were obtained from published sources and government databases. The study predicted the number of chromosomal anomalies detected (trisomies 21, 13, and 18), invasive procedures and euploid fetal losses, direct costs, and incremental cost-effectiveness ratios.

RESULTS

Of the 13 strategies compared, eight identified fewer cases at a higher cost than at least one of the remaining five strategies. Integrated serum screening with conditional NIPT had the lowest cost, and the cost per case detected was $63 139, with a 90% reduction of invasive procedures. The number of cases identified was improved with four other screening strategies, but with increasing of incremental costs per case (from $61 623 to $1 553 615). Results remained robust, except when NIPT costs and risk cut-offs varied.

CONCLUSION

NIPT as a second-tier test for high-risk women is likely to be cost-effective as compared with screening algorithms not involving NIPT.

Expanded conventional first trimester screening

Objective

The study aims to determine the performance of a five (5) serum marker plus ultrasound screening protocol for T21, T18 and T13.

Method

Specimens from 331 unaffected, 34 T21, 19 T18 and 8 T13 cases were analyzed for free Beta human chorionic gonadotropin, pregnancy‐associated plasma protein A, alpha‐fetoprotein, placental growth factor and dimeric inhibin A. Gaussian distributions of multiples of the median values were used to estimate modeled false positive and detection rates (DR).

Results

For T21, at a 1/300 risk cut‐off, DR of screening with all five serum markers along with nuchal translucency and nasal bone was 98% at a 1.2% false positive rate (FPR). Using a 1/1000 cut‐off, the DR was 99% with a 2.6% FPR. For T18/13 with free Beta human chorionic gonadotropin, pregnancy‐associated plasma protein A, placental growth factor and nuchal translucency at a 1/150 cut‐off, DR was 95% at a 0.5% FPR while at a 1/500 risk cut‐off, DR was 97% at a 1.2% FPR.

Conclusion

An expanded conventional screening test can achieve very high DRs with low FPRs. Such screening fits well with proposed contingency protocols utilizing cell‐free DNA as a secondary or reflex but also provides the advantages of identification of pregnancies at risk for other adverse outcomes such as early‐onset preeclampsia. © 2017 Eurofins NTD, LLC. Prenatal Diagnosis published by John Wiley & Sons, Ltd.

What's already known about this topic?

Conventional Down syndrome screening with ultrasound markers and free Beta hCG and PAPP‐A has been successfully utilized for nearly 20 years to screen for trisomies 21, 18 and 13.

Cell‐free DNA screening has much higher detection and lower false positive rates but is expensive.

What does this study add?

An expanded conventional screen with nuchal translucency and nasal bone that includes additional serum markers AFP, placental growth factor and dimeric inhibin A can detect 98% of trisomy 21 and 95% of trisomy 18/13 cases at a false positive rate of 1.2% and 0.5%, respectively.

Offering cell‐free DNA testing to those patients found at increased risk with the expanded screen maintains the detection efficiency but brings the invasive testing rate to an exceedingly low level.

Development and evaluation of training resources to prepare health professionals for counselling pregnant women about non-invasive prenatal testing for Down syndrome: a mixed methods study

BACKGROUND

The availability of non-invasive prenatal testing (NIPT) for aneuploidies is expanding rapidly throughout the world. Training health professionals to offer NIPT in a way that supports informed choice is essential for implementation. The aim of this study was to develop and evaluate a training package for health professionals to support the introduction of NIPT into clinical practice.

METHODS

Training on NIPT was offered to health professionals, primarily midwives, involved in Down syndrome screening and testing in eight hospitals located in England and Scotland as part of a research study evaluating the implementation of NIPT in the UK National Health Service. Training was evaluated using a mixed methods approach that included quantitative questionnaires at three time points and post-training qualitative interviews. The questionnaires measured confidence, self-perceived knowledge and actual knowledge about NIPT for Down syndrome. Interviews explored opinions about the training and experiences of offering NIPT.

RESULTS

The training provided to the health professionals was found to positively impact on their confidence in discussing NIPT with women in their clinic, and both their perceived and actual knowledge and understanding of NIPT was improved. Knowledge remained weak in four areas; cell-free fetal DNA levels increase with gestation; turnaround time for NIPT results; cell-free fetal DNA is placental in origin; and NIPT false positive rate.

CONCLUSIONS

Training materials, including a lesson plan, PowerPoint presentation and written factsheet on NIPT, have been developed and evaluated for use in educating midwives and supporting the introduction of NIPT. Implementation of training should include a greater focus on the areas where knowledge remained low. Some groups of midwives will need additional training or support to optimise their confidence in discussing NIPT with women.

Diagnostic performance and costs of contingent screening models for trisomy 21 incorporating non-invasive prenatal testing

BACKGROUND

Contingent screening for trisomy 21 using non-invasive prenatal testing has the potential to reduce invasive diagnostic testing and increase the detection of trisomy 21.

AIM

To describe the diagnostic and economic performance of prenatal screening models for trisomy 21 that use non-invasive prenatal testing as a contingent screen across a range of combined first trimester screening risk cut-offs from a public health system perspective.

METHODS

Using a hypothetical cohort of 300 000 pregnancies, we modelled the outcomes of 25 contingent non-invasive prenatal testing screening models and compared these to conventional screening, offering women with a high-risk (1 > 300) combined first trimester screening result an invasive test. The 25 models used a range of risk cut-offs. High-risk women were offered invasive testing. Intermediate-risk women were offered non-invasive prenatal testing. We report the cost of each model, detection rate, costs per diagnosis, invasive tests per diagnosis and the number of fetal losses per diagnosis.

RESULTS

The cost per prenatal diagnosis of trisomy 21 using the conventional model was $51 876 compared to the contingent models which varied from $49 309-66 686. The number of diagnoses and cost per diagnosis increased as the intermediate-risk threshold was lowered. Results were sensitive to trisomy 21 incidence, uptake of testing and cost of non-invasive prenatal testing.

CONCLUSION

Contingent non-invasive prenatal testing models using more sensitive combined first trimester screening risk cut-offs than conventional screening improved the detection rate of trisomy 21, reduced procedure-related fetal loss and could potentially be provided at a lower cost per diagnosis than conventional screening.

First trimester contingent screening for trisomies 21,18,13: is this model cost efficient and feasible in public health system?

PURPOSE

To evaluate the effectiveness of three different first trimester screening models for trisomies 21, 18 and 13, in terms of detection rate, invasive test rate and final costs.

MATERIAL AND METHODS

We analyzed the distribution of risk for trisomies 21, 18 and 13 in a population of 20,831 singleton pregnancies based on maternal age, fetal heart rate, nuchal translucency, free beta human chorionic gonadotropin and pregnancy-associated plasma protein A (Combined test). On the basis of our data, we estimated the performance and cost of screening for trisomies using three different models at specific cutoffs: Combined test; Cell free DNA test and Contingent screening test.

RESULTS

Using Combined test, DR for major trisomies was estimated to be 94.92%, invasive test rate was 6.3%. cfDNA would result in a DR of 97.92%, with an invasive test rate of 3.64%. Contingent screening approach would result in an overall DR of 97.82, with a rate for invasive procedure of 1.36% and a final cost lower than other screening policies (2,338,433 euro vs 5,796,060 of cfDNA and 2,385,473 of Combined test).

CONCLUSIONS

Contingent screening test could be a cost-efficient and feasible first trimester screening test for aneuploidies in public health system.