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

Focus on the frontier issue: progress in noninvasive prenatal screening for fetal trisomy from clinical perspectives

The discovery of cell-free fetal DNA (cffDNA) in maternal blood and the rapid development of massively parallel sequencing have revolutionized prenatal testing from invasive to noninvasive. Noninvasive prenatal screening (NIPS) based on cffDNA enables the detection of fetal trisomy through sequencing, comparison, and bioassays. Its accuracy is better than that of traditional screening methods, and it is the most advanced clinical application of high-throughput sequencing technologies. However, the existing sequencing methods are limited by high costs and complex sequencing procedures. These limitations restrict the availability of NIPS for pregnant women. Many amplification methods have been developed to overcome the limitations of sequencing methods. The rapid development of non-sequencing methods has not been accompanied by reviews to summarize them. In this review, we initially describe the detection principles for sequencing-based NIPS. We summarize the rapidly evolving amplification technologies, focusing on the need to reduce costs and simplify the procedures. To ensure that the testing systems are feasible and that the testing processes are reliable, we expand our vision to the clinic. We evaluate the clinical validity of NIPS in terms of sensitivity, specificity, and positive predictive value. Finally, we summarize the application guidelines and discuss the corresponding quality control methods for NIPS. In addition to cffDNA, extracellular vesicle DNA, RNA, protein/peptide, and fetal cells can also be detected as biomarkers of NIPS. With the development of prenatal testing, NIPS has become increasingly important. Notably, NIPS is a screening test instead of a diagnostic test. The testing methods and procedures used in the NIPS process require standardization.

The quality of published health economic evaluations on screening programs in China: a systematic review and quantitative appraisal

BACKGROUND

This study seeks to assess the quality of HEEs reporting on screening programs over the last 20 years in China, to identify potential predictors of reporting quality.

METHODS

We performed a literature search of HEE studies published in PubMed, Embase, CNKI, and WANFANG from 2000 to 2021. The search terms included 'screening,' 'China,' 'CEA,' 'CBA,' 'CUA,' and all other names for health economic evaluation. Two reviewers independently extracted data and assessed the reporting quality using CHEERS checklist. A generalized linear regression analysis was used to identify the predictors of reporting quality.

RESULTS

133 of 1,281 identified studies was included. The reporting quality scores showed an increasing trend and the mean score was 0.56. Some items were underreported, such as study perspective, discount rate, measurement of effectiveness, analytical methods, uncertainty, heterogeneity etc. Five factors (year of publication, journal type, first author's affiliation, economic evaluation type, specialty journals or not) predicted a higher score of reporting quality in the regression analyses (P < 0.05).

CONCLUSIONS

Overall, the quality of HEEs on screening programs in China showed an improving trend. Given the significance of reporting quality, it is advisable to report HEE results following standard evaluation guidelines to improve their transparency.

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.

A Cost-Effectiveness Analysis of Screening Strategies Involving Non-Invasive Prenatal Testing for Trisomy 21

Introduction

In accordance with social development, the proportion of advanced maternal age (AMA) increased and the cost of non-invasive prenatal testing (NIPT) decreased.

Objective

We aimed to investigate the benefits and cost-effectiveness of NIPT as primary or contingent strategies limited to the high-risk population of trisomy 21 (T21).

Methods

Referring to parameters from publications or on-site verification, a theoretical model involving 1,000,000 single pregnancies was established. We presented five screening scenarios, primary NIPT (Strategy 1), contingent NIPT after traditional triple serum screening higher than 1/300 or 1/1,000 (Strategy 2-1 or 2-2), and age-based Strategy 3. Strategy 3 was stratified, with the following options: (1) for advanced maternal age (AMA) of 40 years and more, diagnostic testing was offered, (2) for AMA of 35-39 years, NIPT was introduced, (3) if younger than 35 years of age, contingent NIPT with risk higher than 1:300 (Strategy 3-1) or 1:1,000 (Strategy 3-2) will be offered. The primary outcome was an incremental cost analysis on the baseline and alternative assumptions, taking aging society, NIPT price, and compliance into consideration. The strategy was "appropriate" when the incremental cost was less than the cost of raising one T21 child (0.215 million US$). The second outcome included total cost, cost-effect, cost-benefit analysis, and screening efficiency.

Results

Strategy1 was costly, while detecting most T21. Strategy 2-1 reduced unnecessary prenatal diagnosis (PD) and was optimal in total cost, cost-effect, and cost-benefit analysis, nevertheless, T21 detection was the least. Strategy 3 induced most of the PD procedures. Then, setting Strategy2-1 as a baseline for incremental cost analysis, Strategy 3-1 was appropriate. In sensitivity analysis, when the NIPT price was lower than 47 US$, Strategy 1 was the most appropriate. In a society with more than 20% of people older than 35 years of age, the incremental cost of Strategy 3-2 was proper.

Conclusion

Combined strategies involving NIPT reduced unnecessary diagnostic tests. The AMA proportion and NIPT price played critical roles in the strategic decision. The age-based strategy was optimal in incremental cost analysis and was presented to be prominent as AMA proportion and NIPT acceptance increased. The primary NIPT was the most effective, but only at a certain price, it became the most cost-effective strategy.

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.

Psychometric Assessment of the Mandarin Version of the Decisional Conflict Scale with Pregnant Women Making Prenatal Test Decisions

PURPOSE

Women with high-risk pregnancies are often required to make choices about further prenatal testing for Down syndrome, but the decisional conflict they face is poorly understood. This study aimed to test the validity and reliability of the Mandarin version of the decisional conflict scale (M-DCS) in Chinese women with high-risk pregnancies making choices about further prenatal testing for Down syndrome.

PATIENTS AND METHODS

A methodological study was conducted to determine the psychometric properties of the M-DCS, specially, reliability and content, construct, and concurrent validity. The convenience sample comprised 240 pregnant women with high risk for Down syndrome attending the out-patient clinic of the study hospital in Guangzhou, China.

RESULTS

The five-factor model of M-DCS was supported by confirmatory factor analysis with a satisfactory fit to the data (RMSEA <0.08, RMR <0.05, GFI, CFI, NFI, and IFI all >0.90, except AGFI=0.88 PNFI = 0.76). The internal consistency of the M-DCS was high, with Cronbach's α of 0.94.

CONCLUSION

The reliability and validity (content, construct, and concurrent) of the M-DCS were all demonstrated as good. This instrument is an important tool for researchers and health-care providers working with women with high-risk pregnancies who need to make choices about further prenatal testing for Down syndrome.

The Knowledge, Attitude, Practices, and Satisfaction of Non-Invasive Prenatal Testing among Chinese Pregnant Women under Different Payment Schemes: A Comparative Study

Non-invasive prenatal testing (NIPT) for aneuploidy screening has been widely applied across China, and costs can affect Chinese pregnant women’s choices. This study aims to assess the knowledge, attitude, practices (KAP) and satisfaction regarding NIPT among pregnant women in China, and to further explore the relationship between payment schemes and women’s acceptability of and satisfaction with NIPT. A questionnaire survey was performed in Shenzhen and Zhengzhou, China, which separately applied “insurance coverage” and “out-of-pocket” payment scheme for NIPT. The major differences between the two cities were compared using chi-square test, Wilcoxon rank sum test, and propensity score matched analysis. Logistic regression models were applied to explore predictors for women’s acceptability and satisfaction. Compared with Zhengzhou participants, a higher proportion of Shenzhen women had heard of NIPT (87.30% vs. 64.03%), were willing to receive NIPT (91.80% vs. 80.43%) and had taken NIPT (83.12% vs. 54.54%), while their satisfaction level was lower. Having NIPT-related knowledge was associated with higher acceptability, and receiving genetic counseling helped to improve satisfaction. Besides, women with higher annual household incomes were more likely to take and be satisfied with NIPT. In conclusion, more attention should be paid to health education, subsidies for NIPT, and genetic counseling.

Is Noninvasive Prenatal Screening Appropriate for Pregnant Women Age 35 or Older In Cases if Isolated Fetal Nasal Bone Abnormalities in The Chinese Han Population?

Background

Ethnic background may affect the prevalence of nasal bone absence and the length of the nasal bone. This study aimed to elucidate the significance of absent or hypoplastic fetal nasal bone in the Chinese Han population and to formulate an optimal management plan for patients age 35 or older in cases of isolated abnormal fetal nasal bone.

Material/Methods

We prospectively assigned pregnant women whose fetuses had nasal bone absence or hypoplasia to separate groups according to their choice for noninvasive prenatal screening (NIPS) between January 1, 2013, and December 31, 2018. Demographic data, ultrasound findings, results of conventional maternal serum screening and NIPS, fetal karyotype, pregnancy outcomes, and expenses associated with prenatal testing were recorded. The incidence and odds ratio of nasal bone abnormality and the sensitivity and specificity of different prenatal genetic screening tests were calculated.

Results

A total of 1946 cases with fetal nasal bone absence or hypoplasia were included. Cases of isolated nasal bone abnormality (1736 cases) were divided into the NIPS group (Gr 1, n=429) and the non-NIPS group (Gr 2, n=1307). Sixty-four cases involved chromosomal abnormality. The sensitivity, specificity, and positive and negative predictive values of NIPS in Gr 1 were 100%, 100%, 100%, and 100%, respectively. The odds ratio of fetal chromosomal abnormalities for isolated fetal nasal bone abnormalities when maternal age was ≥35 was 4.615 (95% CI: 1.592–13.381). The cost-effectiveness ratio of contingent screening (NIPS first) was significantly lower than amniocentesis directly.

Conclusions

The nasal bone provides an important marker for chromosome abnormalities in some populations, but to a lesser extent in the Chinese Han population. NIPS is an excellent first option for follow-up among pregnant women age ≥35 in cases of absent or hypoplastic fetal nasal bone in the first trimester ultrasound scan.

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.