The influence of risk estimates obtained from maternal serum screening on amniocentesis rates

A cost-effectiveness analysis of cell free DNA as a replacement for serum screening for Down syndrome

OBJECTIVE

The aim of this article is to determine the cost effectiveness of cell free DNA (cfDNA) as a replacement for integrated screening using a societal cost perspective.

METHOD

This study used Monte-Carlo simulation with one-way and probabilistic sensitivity analysis.

RESULTS

Cell free DNA is more effective and less costly than integrated screening. The incremental cost-effectiveness ratio for cfDNA relative to the integrated test was -$277 955 per case detected (95th percent confidence interval -$881 882 to $532 785).

CONCLUSION

Cell free DNA screening is a cost-effective replacement for maternal serum screening when the lifetime costs of Down syndrome live births are considered. The adoption of cfDNA screening would save approximately $277 955 for each additional case detected over integrated screening.

Clinical implementation of routine screening for fetal trisomies in the UK NHS: cell-free DNA test contingent on results from first-trimester combined test

OBJECTIVES

Cell-free DNA (cfDNA) analysis of maternal blood for detection of trisomies 21, 18 and 13 is superior to other methods of screening but is expensive. One strategy to maximize performance at reduced cost is to offer cfDNA testing contingent on the results of the first-trimester combined test that is used currently. The objectives of this study were to report the feasibility of implementing such screening, to examine the factors affecting patient decisions concerning their options for screening and decisions on the management of affected pregnancies and to report the prenatal diagnosis of fetal trisomies and outcome of affected pregnancies following the introduction of contingent screening.

METHODS

We examined routine clinical implementation of contingent screening in 11,692 singleton pregnancies in two National Health Service (NHS) hospitals in the UK. Women with a risk ≥ 1 in 100 (high-risk group) were offered options of invasive testing, cfDNA testing or no further testing, and those with a risk between 1 in 101 and 1 in 2500 (intermediate-risk group) were offered cfDNA testing or no further testing. The trisomic status of the pregnancies was determined by prenatal or postnatal karyotyping or by examination of the neonates.

RESULTS

In the study population of 11,692 pregnancies, there were 47 cases of trisomy 21 and 28 of trisomies 18 or 13. Screening with the combined test followed by invasive testing for all patients in the high-risk group potentially could have detected 87% of trisomy 21 and 93% of trisomies 18 or 13, at a false-positive rate of 3.4%; the respective values for cfDNA testing in the high- and intermediate-risk groups were 98%, 82% and 0.25%. However, in the high-risk group, 38% of women chose invasive testing and 60% chose cfDNA testing; in the intermediate-risk group 92% opted for cfDNA testing. A prenatal diagnosis was made in 43 (91.5%) pregnancies with trisomy 21 and all pregnancies with trisomies 18 or 13. In many affected pregnancies the parents chose to avoid testing or termination and 32% of pregnancies with trisomy 21 resulted in live births.

CONCLUSIONS

Screening for fetal trisomies by cfDNA analysis of maternal blood, contingent on the results of the combined test, can be implemented easily in routine clinical practice. In the high-risk group from the combined test, most but not all women chose cfDNA testing rather than invasive testing. Performance of screening for trisomy 21 was superior by the cfDNA test than by the combined test. However, prenatal detection of trisomies and pregnancy outcome depend not only on performance of screening tests but also on parental choice.

UK NHS pilot study on cell-free DNA testing in screening for fetal trisomies: factors affecting uptake

OBJECTIVE

This study reports on the clinical implementation of cell-free DNA (cfDNA) testing, contingent on the results of the combined test, in screening for fetal trisomies 21, 18 and 13 in two UK National Health Service hospitals. Women with a combined-test risk of ≥ 1:100 (high risk) were offered the options of chorionic villus sampling (CVS), cfDNA testing or no further testing and those with a risk of 1:101 to 1:2500 (intermediate risk) were offered cfDNA or no further testing. The objective of the study was to examine the factors affecting patient decisions concerning their options.

METHODS

Combined screening was performed in 6651 singleton pregnancies in which the risk for trisomies was high in 260 (3.9%), intermediate in 2017 (30.3%) and low in 4374 (65.8%). Logistic regression analysis was used to determine which factors among maternal characteristics, fetal nuchal translucency thickness (NT) and risk for trisomies were significant predictors of opting for CVS in the high-risk group and opting for cfDNA testing in the intermediate-risk group.

RESULTS

In the high-risk group, 104 (40.0%) women opted for CVS; predictors for CVS were increasing fetal NT and increasing risk for trisomies, while the predictor against CVS was being of Afro-Caribbean racial origin (r = 0.366). In the intermediate-risk group, 1850 (91.7%) women opted for cfDNA testing; predictors for cfDNA testing were increasing maternal age, increasing risk for trisomies and university education, while predictors against cfDNA testing were being of Afro-Caribbean racial origin, smoking and being parous (r = 0.105).

CONCLUSIONS

This study has identified factors that can influence the decision of women undergoing combined screening in favor of or against CVS and in favor of or against cfDNA testing.

Assessing the impact of the SOGC recommendations to increase access to prenatal screening on overall use of health resources in pregnancy

OBJECTIVES

The recommendation by the Society of Obstetricians and Gynaecologists of Canada that prenatal screening for fetal aneuploidy be offered to all pregnant women is an important change in clinical obstetrics. However, it is unknown how this recommendation might affect the use of other health resources during pregnancy.

METHODS

Twelve clinical and administrative databases were linked, and care paths outlining typical service use in pregnancy were created based on the type of prenatal screening accessed (first trimester screening [FTS], maternal serum screening [MSS], invasive testing only, or no screening and/or diagnosis). Logistic, Poisson, and negative binomial models were applied to the data to examine the association between use of prenatal screening/diagnosis and other health services during pregnancy.

RESULTS

Women who accessed prenatal screening/diagnosis were significantly more likely to have a consultation with a medical geneticist (FTS OR 2.42; 95% CI 1.75 to 3.33; MSS OR 4.84; 95% CI 2.92 to 8.03; and invasive testing OR 8.58; 95% CI 5.28 to 13.94), and women who accessed FTS had more prenatal visits (FTS incidence rate ratio 1.03; 95% CI 1.01 to 1.05) than women who did not access prenatal screening/diagnosis. Uptake of invasive tests did not differ between women who accessed FTS and those who accessed MSS. Use of prenatal screening/diagnosis was not significantly associated with use of most other health resources

CONCLUSION

In a publicly funded health care system, understanding the impact of recommendations to increase access to a specific service on other services is important. Recommendations to increase access to prenatal screening services may have some unanticipated downstream effects on the use of other services during pregnancy. However, most aspects of health resource use in pregnancy do not appear to be influenced by the use of prenatal screening services.

Factors determining uptake of invasive testing following first-trimester combined testing

OBJECTIVE

This study aims to analyze differences in characteristics between women who opted for invasive testing after first-trimester combined testing and those who did not.

METHOD

Follow-up was performed in 20 215 combined tests conducted between 2007 and 2011 in the central region of the Netherlands. Multivariate logistic regression analysis compared variables (Down syndrome risk estimate, maternal age, previous Down syndrome pregnancy, IVF/ICSI, parity and nuchal translucency measurement) between different groups.

RESULTS

65.4% of women with a Down syndrome risk estimate ≥1 in 200 opted for invasive 49 testing. In a multivariate model, women opting for invasive testing were significantly younger (odds ratio 0.92; 95% confidence interval 0.88-0.95) and less likely to have had IVF/ICSI (odds ratio 0.57; 95% confidence interval 0.37-0.87) than women opting out on invasive testing. In this high risk group, women <36 years opted for invasive testing more frequently, regardless of their Down syndrome risk estimate magnitude. Women ≥36 years let the magnitude of the risk estimate count significantly in their decision to opt for invasive testing.

CONCLUSION

Because of the dissimilarity in the offer of prenatal screening and invasive diagnosis in the Dutch prenatal screening policy, women <36 years and women >36 years make different choices when confronted with similar Down syndrome risk estimates.

A systematic review of issues around antenatal screening and prenatal diagnostic testing for genetic disorders: women of Asian origin in western countries

Antenatal screening has become standard practice in many countries. However, not all pregnant women choose to be tested. In the UK, the incidence of some birth defects is found to be higher in babies of Asian women than in those of women from other ethnic groups, while there is some evidence suggesting that ethnic minorities, especially Asian women, are less likely to undergo antenatal screening and prenatal diagnosis, the reasons for which are unclear. This study aims to identify and describe the literature on issues around antenatal screening and prenatal diagnostic testing for genetic disorders among women of Asian descent in western countries. The Medline, CINAHL, ASSIA and PsycInfo databases were searched for the period of 1995 and 2010. Twenty-one studies met the inclusion criteria and were therefore reviewed. In general, Asian women were found to hold favourable attitudes towards testing. However, they reported a poorer understanding of testing than white women and not being offered a test, and were less able to make informed choices. Asian women in the UK and Australia were found to be less likely than their white counterparts to have undergone prenatal diagnosis, while such differences were not found in the USA and Canada. The equity of access to quality antenatal care, alongside comprehensive well thought out antenatal screening programmes, can be assured if strategies are in place which actively involve all ethnic groups and take account of social and cultural appropriateness for the population served. An understanding of broad factors that inform women's decision-making on test uptake would help health professionals provide women and their families with more culturally sensitive information and support that they may additionally need to make more informed choices.

Noninvasive prenatal diagnosis: pregnant women's interest and expected uptake

OBJECTIVE

To investigate pregnant women's level of future interest in noninvasive prenatal diagnosis (NIPD) and what factors might affect expected uptake of this testing.

METHOD

Written questionnaires were administered to women in their third trimester.

RESULTS

One hundred fourteen women returned the questionnaire (80.9% response rate). Of these, 71.9% reported interest in NIPD, 22.7% were ambivalent, and 5.4% were uninterested. Safety of the fetus was the single most important factor in 75% of women's decisions. Factors associated with increased interest in NIPD included: older age (p = 0.036), higher education (p = 0.013), Caucasian or Asian ethnicity (p = 0.011), and higher likelihood to terminate an affected pregnancy (p = 0.002). Nearly 20% of women reported that they would do whatever their doctor recommended regarding NIPD, and 94.4% of women wished to meet with a genetic counselor at some point to discuss NIPD.

CONCLUSION

The majority of pregnant women report hypothetical interest in NIPD, primarily because of increased safety for the fetus, although a significant minority are uninterested or ambivalent. Discussions with healthcare providers regarding NIPD, and their recommendations, are likely to be an important factor in women's decisions about this testing. As such, adequate discussion of the implications of prenatal diagnostic testing will be critical.

Uptake of prenatal diagnostic testing and the effectiveness of prenatal screening for Down syndrome

OBJECTIVES

To map prenatal screening and diagnostic testing pathways in Victorian pregnant women during 2003 to 2004; measure the impact of prenatal diagnostic testing uptake on the effectiveness of prenatal screening for Down syndrome; and assess factors influencing uptake of diagnostic testing following screening.

METHODS

State-wide data collections of prenatal screening and diagnostic tests were linked to all Victorian births and pregnancy terminations for birth defects.

RESULTS

Overall, 52% of women had a prenatal test (65 692/126 305); screening (44.9%), diagnostic testing (3.9%), or both (3.2%). Uptake of diagnostic testing was 71.4% (2390/3349) after an increased risk screen result, and 2.5% (1381/54 286) after a low risk result. Variation in uptake of diagnostic testing reduced the effectiveness of the screening program by 11.2%: from 87.4% (sensitivity - 125/143) to 76.2% (prenatal diagnoses of Down syndrome - 109/143). In both the increased and low risk groups, uptake was influenced by absolute numerical risk, as well as by the change in numerical risk from a priori risk.

CONCLUSIONS

This comprehensive follow-up demonstrates clearly that numerical risk is being used to aid in decision making about confirmatory diagnostic testing. Collectively, these fundamental individual decisions will impact on the overall effectiveness of screening programmes for Down syndrome.

Prenatal testing for Down syndrome: comparison of screening practices in the UK and USA

Prenatal testing for Down Syndrome is a topic covered in every genetic counselor's training as it constitutes the main workload of genetic counselors in prenatal settings. Most Western countries nowadays offer some type of testing for Down Syndrome. However, practices vary according to country with regards to what tests are offered, insurance coverage and the legal situation concerning the option of terminating an affected pregnancy. In view of the growing interest in international genetic counseling issues, this article aims to compare prenatal testing practices in two English-speaking countries: the United Kingdom and the United States of America. A case will be presented to highlight some of the differences in practice. The topic underlines important implications for genetic counseling practice, such as patients' understanding of testing practices, risk perception, counseling provision and impact of prenatal testing results.

Does labeling prenatal screening test results as negative or positive affect a woman's responses?

OBJECTIVE

We tested whether adding interpretive labels (eg, "negative test") to prenatal genetic screening test results changes perceived risk and preferences for amniocentesis.

STUDY DESIGN

Women (N = 1688) completed a hypothetical pregnancy scenario on the Internet. We randomly assigned participants into 2 groups: high risk of fetal chromosomal problems (12.5/1000) or low risk (2/1000). After prenatal screening, estimated risk was identical (5/1000) for all participants, but results were provided either alone or with interpretive labels.

RESULTS

When receiving test results without labels, all participants react similarly. With labels, the participants who received "positive" or "abnormal" results reported a higher perceived risk (P < .001), greater worry (P < .001), and greater interest in amniocentesis (57% vs 37%; P < .001) than did the participants who received "negative" or "normal" results.

CONCLUSION

Interpretive labels for test results can induce larger changes to a woman's risk perception and behavioral intention than can numeric results alone, which create decision momentum. This finding has broad clinical implications for patient-provider communication.