Comparison of First and Second Trimester Aneuploidy Risk Assessment

Perinatal outcomes in euploid pregnancies with 'double-positive' first trimester prenatal screening for trisomy 18 and 21

OBJECTIVE

The objective of this study was to investigate whether women who screened positive for both trisomy 18 (T18) and trisomy 21 (T21) yet had euploid karyotypes were at increased risk for adverse pregnancy outcomes.

STUDY DESIGN

This was a retrospective cohort study of women who had first trimester aneuploidy screening. Double-positive subjects had risks greater than screening cutoffs for T21 and T18 and confirmed euploid karyotypes. Singleton subjects were matched 1:2 by maternal age to controls with normal screening. Perinatal outcomes were investigated using t-tests and χ(2)-tests; statistical significance was set at P<0.05.

RESULT

Of 9733 women who had first trimester screening, 33 euploid pregnancies screened positive for both T21 and T18. Compared with controls, these study subjects were more likely to have abnormalities identified by prenatal ultrasounds, including renal, fetal membrane and fluid, as well as multiple anomalies (P=0.01). In addition, double-positive subjects had a lower mean gestational age at birth (P=0.02) and lower mean birth weight (P=0.03) than controls. Maternal outcomes were not significantly different.

CONCLUSION

Pregnancies with double false-positive first trimester aneuploidy screening were associated with pregnancy/fetal abnormalities.

Meeting patients' education and decision-making needs for first trimester prenatal aneuploidy screening

OBJECTIVE

First trimester aneuploidy screening introduces unique challenges to patient education and informed decision-making. Our study assessed the decision-making process among those pregnant patients presenting for this new form of aneuploidy screening.

METHOD

A survey instrument was used to assess components of decision-making among women who presented for first trimester aneuploidy screening. Knowledge and leading factors in the decision-making process were measured.

RESULTS

Participants (n = 139) demonstrated understanding of the etiology of Down syndrome, but less understanding of its cognitive (65.2%) and physical manifestations (58.7%). Few were able to determine risk from first trimester screen results (36.7%). Participants were more familiar with amniocentesis (84.2%) than chorionic villus sampling (73.4%), though less familiar with procedural risks (29.5% and 28.1%, respectively). The majority of participants ranked the following as key information in their decision: knowledge of their intentions about the outcome of the pregnancy based on the test results (92.4%), knowledge of chorionic villus sampling to evaluate an abnormal result (92.0%), and values and beliefs about termination (89.1%).

CONCLUSION

First trimester aneuploidy screening generates education and decision-making benchmarks for patients and providers. It is important to address these barriers as this new screen becomes a growing part of current prenatal genetic testing offerings.

Risk and uncertainty: shifting decision making for aneuploidy screening to the first trimester of pregnancy

PURPOSE

The clinical introduction of first trimester aneuploidy screening uniquely challenges the informed consent process for both patients and providers. This study investigated key aspects of the decision-making process for this new form of prenatal genetic screening.

METHODS

Qualitative data were collected by nine focus groups that comprised women of different reproductive histories (N = 46 participants). Discussions explored themes regarding patient decision making for first trimester aneuploidy screening. Sessions were audio recorded, transcribed, coded, and analyzed to identify themes.

RESULTS

Multiple levels of uncertainty characterize the decision-making process for first trimester aneuploidy screening. Baseline levels of uncertainty existed for participants in the context of an early pregnancy and the debate about the benefit of fetal genetic testing in general. Additional sources of uncertainty during the decision-making process were generated from weighing the advantages and disadvantages of initiating screening in the first trimester as opposed to waiting until the second. Questions of the quality and quantity of information and the perceived benefit of earlier access to fetal information were leading themes. Barriers to access prenatal care in early pregnancy presented participants with additional concerns about the ability to make informed decisions about prenatal genetic testing.

CONCLUSIONS

The option of the first trimester aneuploidy screening test in early pregnancy generates decision-making uncertainty that can interfere with the informed consent process. Mechanisms must be developed to facilitate informed decision making for this new form of prenatal genetic screening.

Cost-effectiveness and accuracy of prenatal Down syndrome screening strategies: should the combined test continue to be widely used?

OBJECTIVE

We analyzed the cost-effectiveness (CE) and performances of commonly used prenatal Down syndrome (DS) screening strategies.

STUDY DESIGN

We performed computer simulations to compare 8 screening options by applying empirical data from Serum, Urine, and Ultrasound Screening Study trials on the population of 110,948 pregnancies. Screening strategies outcomes, CE ratios, and incremental CE ratios were measured.

RESULTS

The most CE DS screening strategy was the contingent screening method (CE ratio of Can$26,833 per DS case). Its incremental CE ratio compared to the second-most CE strategy (serum integrated screening) was Can$3815 per DS birth detected. Among the procedures respecting guidelines, our results identified the combined test as the screening strategy with the highest CE ratio (Can$47,358) and the highest number of procedure-related euploid miscarriages (n = 71).

CONCLUSION

In regard to CE, contingent screening is the best choice. The combined test, which is the most popular screening strategy, shows many limitations.

Improving residents' understanding of issues, comfort levels, and patient needs regarding screening for and diagnosing Down syndrome

OBJECTIVE

This study assessed obstetrics and gynecology and pediatrics residents' knowledge about Down syndrome (DS) and their comfort in delivering a prenatal or postnatal diagnosis of DS before and after interaction with a web-based tutorial.

STUDY DESIGN

A team of physicians, parents, and educational specialists developed an interactive tutorial that asked resident physicians to provide their own responses to "virtual patient" cases related to DS diagnoses in utero and at birth. We tested resident knowledge and comfort-level changes and their satisfaction with the web-based tool.

RESULTS

The study yielded significant improvement in knowledge and level of comfort changes with both obstetrics and gynecology and pediatric resident physicians at 16 programs nationally. There were no significant differences between the 2 specialties.

CONCLUSION

This interactive tutorial is effective in improving physicians' knowledge of and comfort level with imparting accurate, balanced information about DS pre- and postnatally.

Decisional needs assessment regarding Down syndrome prenatal testing: a systematic review of the perceptions of women, their partners and health professionals

OBJECTIVE

To identify decisional needs of women, their partners and health professionals regarding prenatal testing for Down syndrome through a systematic review.

METHODS

Articles reporting original data from real clinical situations on sources of difficulty and/or ease in making decisions regarding prenatal testing for Down syndrome were selected. Data were extracted using a taxonomy adapted from the Ottawa Decision-Support Framework and the quality of the studies was assessed using Qualsyst validated tools.

RESULTS

In all 40 publications covering 32 unique studies were included. The majority concerned women. The most often reported sources of difficulty for decision-making in women were pressure from others, emotions and lack of information; in partners, emotion; in health professionals, lack of information, length of consultation, and personal values. The most important sources of ease were, in women, personal values, understanding and confidence in the medical system; in partners, personal values, information from external sources, and income; in health professionals, peer support and scientific meetings.

CONCLUSION

Interventions regarding a decision about prenatal testing for Down syndrome should address many decisional needs, which may indeed vary among the parties involved, whether women, their partners or health professionals. Very little is known about the decisional needs of partners and health professionals.

Psychiatric phenotypes associated with neurogenetic disorders

Advances in understanding the human genome and clinical application have led to identification of genetically based disorders that have distinctive behavioral phenotypes and risk for serious psychiatric disorders. Some patients have unrecognized genetic disorders presenting as psychiatric symptoms. Practitioners must be knowledgeable about the association between symptoms and underlying genetic bases. Treatment of neurogenetic disorders includes providing information about causes and prognoses. Patients are served best if they remain long term with a multidisciplinary team of providers who recognize the realities of a lifetime course, the high risk for symptom recurrence, and the need for providing information and support to families and coordinating medical and psychiatric care.

Comparison of different strategies in prenatal screening for Down's syndrome: cost effectiveness analysis of computer simulation

OBJECTIVES

To assess and compare the cost effectiveness of three different strategies for prenatal screening for Down's syndrome (integrated test, sequential screening, and contingent screenings) and to determine the most useful cut-off values for risk.

DESIGN

Computer simulations to study integrated, sequential, and contingent screening strategies with various cut-offs leading to 19 potential screening algorithms.

DATA SOURCES

The computer simulation was populated with data from the Serum Urine and Ultrasound Screening Study (SURUSS), real unit costs for healthcare interventions, and a population of 110 948 pregnancies from the province of Québec for the year 2001.

MAIN OUTCOME MEASURES

Cost effectiveness ratios, incremental cost effectiveness ratios, and screening options' outcomes.

RESULTS

The contingent screening strategy dominated all other screening options: it had the best cost effectiveness ratio ($C26,833 per case of Down's syndrome) with fewer procedure related euploid miscarriages and unnecessary terminations (respectively, 6 and 16 per 100,000 pregnancies). It also outperformed serum screening at the second trimester. In terms of the incremental cost effectiveness ratio, contingent screening was still dominant: compared with screening based on maternal age alone, the savings were $C30,963 per additional birth with Down's syndrome averted. Contingent screening was the only screening strategy that offered early reassurance to the majority of women (77.81%) in first trimester and minimised costs by limiting retesting during the second trimester (21.05%). For the contingent and sequential screening strategies, the choice of cut-off value for risk in the first trimester test significantly affected the cost effectiveness ratios (respectively, from $C26,833 to $C37,260 and from $C35,215 to $C45,314 per case of Down's syndrome), the number of procedure related euploid miscarriages (from 6 to 46 and from 6 to 45 per 100,000 pregnancies), and the number of unnecessary terminations (from 16 to 26 and from 16 to 25 per 100,000 pregnancies).

CONCLUSIONS

Contingent screening, with a first trimester cut-off value for high risk of 1 in 9, is the preferred option for prenatal screening of women for pregnancies affected by Down's syndrome.

Application of proteomics for the identification of differentially expressed protein markers for Down syndrome in maternal plasma

BACKGROUND

Despite the large impact of ultrasonographic and biochemical markers on prenatal screening, the ability to accurately diagnose Down syndrome (DS) is still limited and better diagnostic testing is needed.

METHODS

Plasma from 8 women carrying a DS foetus and 12 with non-DS foetuses matched for gestational age, maternal age and ethnicity, in the second trimester of pregnancy, was analysed by two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in order to identify biomarkers for DS.

RESULTS

Gel comparison revealed nine proteins differentially expressed in maternal plasma in women with DS foetuses. Eight proteins, transthyretin (TTHY), ceruloplasmin (CERU), afamin (AFAM), alpha-1-microglobulin (AMBP), apolipoprotein E (APOE), serum amyloid P-component (SAMP), histidine-rich glycoprotein (HRG) and alpha-1-antitrypsin (A1AT) were up-regulated and one, clusterin (CLUS), down-regulated. All nine proteins are known to be involved in foetal growth and development. APOE, SAMP, AFAM and CLUS are associated with the DS phenotype. Western blot and densitometric analysis of APOE and SAMP confirmed the increase of both proteins by 19 and 48% respectively.

CONCLUSIONS

All differentially expressed proteins are candidate biomarkers for DS, providing opportunities for the development of non-invasive prenatal diagnosis. As these are preliminary findings, follow-up experiments are needed for their evaluation.