Contingency Screening Research Articles

Предпочтения беременных и врачей в выборе метода пренатального скрининга: мировой опыт

Многие страны внедряют неинвазивное пренатальное тестирование (НИПТ) в систему общественного здравоохранения в качестве контингентного скрининга для беременных, что позволяет повысить эффективность выявления хромосомных аномалий (ХА) у плода и снизить количество необоснованных инвазивных процедур. Анализ литературных источников показал, что большинство врачей и беременных из групп высокого и промежуточного рисков готовы воспользоваться НИПТ в качестве дополнительного скрининга в связи с его безопасностью, высокой чувствительностью и возможностью раннего получения результатов. Однако обнаружены различия в выборе метода раннего пренатального скрининга ХА между странами, которые зависели от этнических, социо-демографических и религиозных характеристик опрошенных, а также от особенностей политики местного здравоохранения, связанных с необходимостью частичной или полной оплаты пренатального теста и доступностью прерывания беременности. Сделан вывод, что для каждой страны необходимы свои руководства, разработанные с учетом социального контекста, а вопрос о внедрении НИПТ в рутинную практику должен решаться по результатам социологических исследований в больших группах беременных и врачей страны. Many countries are introducing a non-invasive prenatal test, NIPT, into the public health system as a contingent screening for pregnant women, which improves the detection of chromosomal abnormalities of the fetus and reduces the number of unwarranted invasive procedures. Analysis of the literature showed that the majority of doctors and pregnant women from the high and intermediate risk groups are ready to use NIPT as an additional screening due to its safety, high sensitivity and the possibility of early reception of results. However, there were found differences between countries in choosing the method of prenatal screening for chromosomal abnormalities of the fetus, which depend on the ethnic, sociodemographic and religious characteristics of the respondents, as well as on the peculiarities of the local health policy related to the need for partial or full payment of the prenatal test and the availability of abortion. It was concluded that each country needs its own guidelines, developed with taking into account the social context, and the issue of introducing NIPT into routine practice should be decided by the results of sociological research among large groups of pregnant women and healthcare professionals in the country.

Multi-stage contingency-constrained co-planning for electricity-gas systems interconnected with gas-fired units and power-to-gas plants using iterative Benders decomposition

The increasing share of variable renewable energy sources and the improving requirements on system security and reliability are calling for important changes in the integrated energy systems. Hence this paper proposes a multi-stage contingency-constrained co-planning model for electricity-gas systems interconnected with gas-fired units and power-to-gas plants considering the uncertainties of load demand and wind power. The proposed model considers the long-term co-planning for electricity-gas systems with the short-term operation constraints and N-1 reliability criterion, which is formulated as a mixed-integer linear programming problem. First, a scenario reduction method based on affinity propagation clustering is utilized to handle the uncertainties. Afterwards, the N-1 criterion is tackled by a contingency screening method based on line outage distribution factors. Finally, an iterative Benders decomposition method is developed to divide the programming problem into one master investment problem and three subproblems. The iterative process will continue between master problem and each subproblem until an economic, reliable and fuel-supply feasible solution is obtained. In order to verify the feasibility of the proposed model and the effectiveness of the proposed method, case studies are conducted on two different scales of electricity-gas systems.

Non-invasive prenatal screening: A 20-year experience in Italy.

Over the past two decades, there has been a rapid evolution in prenatal screening for fetal chromosome abnormalities. Initially, testing was focused on the identification of affected pregnancies in either the first, or, the second trimester (e.g. the Combined test or the triple test). This was replaced by sequential modalities (e.g. contingent screening) that have enhanced detection while reducing the need for invasive testing. More recently, the introduction of technologies based on cell-free DNA (cfDNA) in maternal plasma and enrichment of fetal cells in maternal circulation have further refined the concept of sequential screening. In this review, we document our experience with serum and ultrasound-based contingent screening where we were able to achieve a detection rate of 96.8%, a false-positive rate of 2.8% and an odds of being affected given a positive result of 1:11. We also describe our initial experience with a novel sequential protocol that includes the analysis of fetal cells in maternal blood.Methods for enrichment for fetal cells cfDNA and cfDNA technologies offer the possibility of greater sensitivity and specificity as well as expansion in the scope of genetic disorders detectable. As costs decline, these technologies will become increasingly used as primary screening tools. In the meantime, sequential use offers a practical approach to maximizing the benefits of prenatal testing.

Evaluation of prenatal contingent screening for chromosomal alterations

Evaluation of prenatal contingent screening for chromosomal alterations

The International Federation of Gynecology and Obstetrics (FIGO) initiative on pre-eclampsia: A pragmatic guide for first-trimester screening and prevention.

The International Federation of Gynecology and Obstetrics (FIGO) initiative on pre-eclampsia: A pragmatic guide for first-trimester screening and prevention.

Research on a Contingency Screening Method for Reliability Evaluation Based on Intuitionistic Fuzzy Decision

Research on a Contingency Screening Method for Reliability Evaluation Based on Intuitionistic Fuzzy Decision

Cell-free DNA and contingent screening: Our first year

IntroductionAnalysis of cell-free DNA (cfDNA) from maternal blood has showed a great potential as a screening method for fetal aneuploidies. cfDNA can be used as a first line screening tool or in a contingent model, after the combined test. MethodsProspective study of women attending for first trimester combined screening in our Hospital, in the first year of contingent cfDNA screening. According to the combined screening test result patients were divided in high-risk (offered invasive test or routine follow-up), intermediate-risk (counselled for cfDNA, invasive or routine follow-up) or low-risk (routine ultrasound follow-up). Pregnancy outcomes and performance of screening were evaluated. A cost-effectiveness analysis was also done. ResultsThe majority of the 1272 enrolled participants were Caucasian (82,6%), multiparous (51,7%) and the median maternal age was 30 years old. Thirty women screened high-risk and 83,3% of them opted for an invasive test. Forty-nine patients had an intermediate risk and 75,5% of them choose cfDNA testing. Our rate of invasive tests decreased from 3.5% to 2.4%. DiscussionThe cut-offs used to determine high and intermediate-risk are based on a compromise between detection rate, pregnancy lost rate and cost. Above a determined cut-off in the intermediate-risk group, the cost for each additional detected trisomy case is very high. One major benefit of this contingent model was the decrease in invasive testing. ConclusionThe contingent cfDNA screening model can be easily implemented in a public hospital with a low-risk population. Since cost/benefit is an important issue, further studies are needed to determine the ideal cut-off for our country.

Online contingency analysis method for multi‐terminal DC distribution networks with renewable resources

In this study, an interval arithmetic-based method has been proposed for contingency analysis of line outage in DC distribution networks. This method incorporates the uncertainties in source/load which become considerable in the system with increasing renewable generations and time-varying loads. Two-stage contingency analysis approach is adopted in this method. For the first stage of contingency screening, a contingency filter has been developed based on interval matrix norm to quickly estimate the bounds of operating state in the post-outage period. For the second stage of detailed analysis to the selected contingencies, the interval analytical model is first transformed into a non-linear programming-based equivalent model. To solve this model accurately and efficiently, successive linear programming and reformulation-linearisation techniques are employed. The proposed method is benchmarked against Monte Carlo simulations and line outage distribution factor-based method.

Screening Hidden N-$k$ Line Contingencies in Smart Grids Using a Multi-Stage Model

This paper addresses an issue in the contingency screening that the probabilities of some high-order N- k contingencies involving multiple element failures may be significantly underestimated in the traditional screening processes. Considering the severe consequences of these hidden contingencies, this practice would impose a potential risk to the system operations. In this paper, we propose a multi-stage approach to screen out these N- k contingencies and reveal their hidden probabilities. The approach is formulated as a bi-level mixed integer linear programming problem and validated by simulations on the IEEE 14-bus and 118-bus systems.

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

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. 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. 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. 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.

Implementation of cell-free DNA-based non-invasive prenatal testing in a National Health Service Regional Genetics Laboratory.

Non-invasive prenatal testing (NIPT) for the detection of foetal aneuploidy through analysis of cell-free DNA (cfDNA) in maternal blood is offered routinely by many healthcare providers across the developed world. This testing has recently been recommended for evaluative implementation in the UK National Health Service (NHS) foetal anomaly screening pathway as a contingent screen following an increased risk of trisomy 21, 18 or 13. In preparation for delivering a national service, we have implemented cfDNA-based NIPT in our Regional Genetics Laboratory. Here, we describe our validation and verification processes and initial experiences of the technology prior to rollout of a national screening service. Data are presented from more than 1000 patients (215 retrospective and 840 prospective) from 'high- and low-risk pregnancies' with outcome data following birth or confirmatory invasive prenatal sampling. NIPT was by the Illumina Verifi® test. Our data confirm a high-fidelity service with a failure rate of ~0.24% and a high sensitivity and specificity for the detection of foetal trisomy 13, 18 and 21. Secondly, the data show that a significant proportion of patients continue their pregnancies without prenatal invasive testing or intervention after receiving a high-risk cfDNA-based result. A total of 46.5% of patients referred to date were referred for reasons other than high screen risk. Ten percent (76/840 clinical service referrals) of patients were referred with ultrasonographic finding of a foetal structural anomaly, and data analysis indicates high- and low-risk scan indications for NIPT. NIPT can be successfully implemented into NHS regional genetics laboratories to provide high-quality services. NHS provision of NIPT in patients with high-risk screen results will allow for a reduction of invasive testing and partially improve equality of access to cfDNA-based NIPT in the pregnant population. Patients at low risk for a classic trisomy or with other clinical indications are likely to continue to access cfDNA-based NIPT as a private test.

A contingent model for cell-free DNA testing to detect fetal aneuploidy after first trimester combined screening.

ObjectiveTo assess the results of the first trimester combined test to design a prenatal protocol for the introduction of the cell-free fetal DNA test as a contingent screening model.MethodAn observational retrospective study in 12,327 singleton pregnancies to analyze the results of the combined first trimester screening, the nuchal translucency ≥97.5 percentile, their cytogenetic results and birth outcomes.ResultsA total of 533 (4.3%) pregnant women had a risk in combined first trimester screening above 1/300. In this group, sixty nine had an unbalanced karyotype. The abnormal/normal karyotype ratio was 1/28 in pregnant women with intermediate risk (1/51-1/300) for trisomy 21 and trisomy 18, 1/58 with intermediate risk just for trisomy 21 and 1/37 with intermediate risk just for trisomy 18. A 19.8% of the unbalanced karyotypes had chromosomal abnormalities other than trisomies 21, 18 and 13. Two false negatives cases at first trimester combined screening presented a nuchal translucency ≥ p97.5th.ConclusionWe propose the introduction of the cell-free fetal DNA test when the risk of first trimester combined screening is intermediate (1/51–1/300) and when nuchal translucency is ≥ p97.5th with a low risk in the combined screening. This policy would allow us to continue to detect uncommon chromosomal abnormalities.

Wide-Area Damping Control using Reduced Copy under Intermittent Observation: A Novel Performance Measure

Insight into the application of observer-driven reduced copy (ORC) to deal with data packet dropout during wide-area oscillation damping control through wind farms (WFs) is developed. The ORC technique tries to emulate the behavior of the power system by using the information of the nominal dynamics under intermittent observation. This brief presents a direct performance measure for ORC. To that end, a standard lemma relating the bound on the norm of the integral over the product of two functions is presented, which is proven using Holder’s inequality. Based on the lemma, an expression is derived for the bound on the norm within an inter-sample interval for difference between the power system states in presence of data dropout and that under ideal communication. Such a bound, when evaluated in a relative sense, would be useful for system operators to perform online contingency screening and ranking from damping performance standpoint without running prohibitively expensive time-domain simulations. In addition, such a bound is also derived for the conventional feedback control (CFC). The data dropout is modeled using the Gilbert-Elliott model. The analytical results are validated using time-domain simulation of a 16-machine, 5-area New England-New York system with two doubly fed induction generator-based WFs.

Routine first-trimester screening for fetal trisomies in twin pregnancy: cell-free DNA test contingent on results from combined test.

To report on the routine clinical implementation of cell-free DNA (cfDNA) analysis of maternal blood for trisomies 21, 18 and 13, contingent on the results of the first-trimester combined test in twin pregnancy. Screening for trisomies 21, 18 and 13 was carried out in 959 twin pregnancies by assessment of a combination of maternal age, fetal nuchal translucency thickness, and serum free β-human chorionic gonadotropin and pregnancy-associated plasma protein-A at 11-13 weeks' gestation in two UK NHS hospitals. Women in the high-risk group (risk ≥ 1 in 100) were offered the option of invasive testing, cfDNA testing or no further testing, and those in the intermediate-risk group (risk 1 in 101 to 1 in 2500 in the first phase of the study and 1 in 101 to 1 in 500 in the second phase) were offered cfDNA or no further testing. The trisomic status of the pregnancies was determined by prenatal or postnatal karyotyping or examination of the neonates. In 42 (4.4%) of the 959 pregnancies, there was termination, miscarriage or stillbirth with no known karyotype or there was loss to follow-up. The 917 pregnancies with known trisomic status of both twins included six that were discordant for trisomy 21, four that were discordant for trisomy 18 and 907 with no trisomy 21, 18 or 13. Following combined screening, 47 (5.1%), 203 (22.1%) and 667 (72.7%) of the pregnancies were classified as high risk, intermediate risk and low risk, respectively. The high-risk group included five (83.3%) cases of trisomy 21 and three (75.0%) of trisomy 18. The cfDNA test was carried out in 224 pregnancies and results were provided in 214 (95.5%); this group included six pregnancies with trisomy 21, three with trisomy 18 and 206 with no trisomy 21, 18 or 13. The cfDNA test classified correctly as screen positive all six cases of trisomy 21 and two of the three with trisomy 18, and as screen negative for each of the trisomies all 206 unaffected pregnancies. Contingent screening led to prenatal detection of all cases of trisomy 21 and three of four with trisomy 18. This study has demonstrated the feasibility of introducing cfDNA testing, contingent on the results of the first-trimester combined test for major trisomies, in a routine population of twin pregnancies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Screening for Common Fetal Trisomies in Twin Pregnancies: First-Trimester Combined, Cell-Free DNA, or Both?

Objective: To examine the distribution of risks for fetal trisomies after first-trimester combined screening in twins and to investigate different strategies for clinical implementation of cell-free DNA (cfDNA) testing. Methods: We retrospectively analyzed all twin pregnancies undergoing first-trimester combined screening over a 10 years’ period. The population was stratified according to various risk cut-offs, and we examined different screening strategies for implementation of cfDNA testing in terms of impact on invasive testing rate, cfDNA test failure rate, and economic costs. Results: We included 572 twin pregnancies: 480 (83.92%) dichorionic and 92 (16.08%) monochorionic. Performing a first-line combined screening and offering cfDNA testing to the group with a risk between 1 in 10 and 1 in 1,000, would lead to an invasive testing rate of 2.45%, and cfDNA testing would be performed in 22.20% of the population. This strategy would be cost-neutral compared to universal combined screening alone. Conclusions: First-trimester combined screening results can be used to stratify twin pregnancies into different risk categories and select those that could be offered cfDNA testing. A contingent screening strategy would substantially decrease the need for invasive testing in twins and it would be cost-neutral compared to combined testing alone.

OP01.03: A clinical comparative study between conventional fetal aneuploidy screening and contingent screening using the non‐invasive prenatal testing

OP01.03: A clinical comparative study between conventional fetal aneuploidy screening and contingent screening using the non‐invasive prenatal testing

Probabilistic Performance Index based Contingency Screening for Composite Power System Reliability Evaluation

Composite power system reliability involves assessing the adequacy of generation and transmission system to meet the demand at major system load points. Contingency selection was being the most tedious step in reliability evaluation of large electric systems. Contingency in power system might be a possible event in future which was not predicted with certainty in earlier research. Therefore, uncertainty may be inevitable in power system operation. Deterministic indices may not guarantee the randomness in reliability assessment. In order to account for volatility in contingencies, a new performance index proposed in the current research. Proposed method assimilates the uncertainty in computational procedure. Reliability test systems like Roy Billinton Test System-6 bus system and IEEE-24 bus reliability test systems were used to test the effectiveness of a proposed method.

PMD38 - CELL-FREE FETAL DNA AS A CONTINGENT PRENATAL SCREENING OF TRISOMIES CONDITIONAL TO A RISK ≥ 1:1,000 FOR ITALIAN PREGNANT WOMEN: AN ECONOMIC EVALUATION

NIPT has been developed in order to introduce non-invasive genetic techniques in prenatal screening. They show high accuracy in the detection of common fetal autosomal trisomies (i.e. T21, T18, T13) in pregnant women. The aim of the study was to evaluate the financial and clinical impact on the Italian NHS of the contingent use of NIPT in comparison to current clinical practice. A budget impact analysis was developed in the short-term period until child birth, and the target population was represented by Italian singleton-pregnant women (508,705). The analysis compared two scenarios: current clinical practice vs introduction of NIPT as a contingent screening for women with a risk ≥ 1:1,000 from the current clinical practice. NIPT reduced the number of invasive tests performed by 71%, with a consequent decrease in the number of invasive-related miscarriages (from 532 to 156). The overall trisomy detection rate increased by 3% compared to the standard clinical practice. Following NIPT introduction, total short term costs per year decreased by €19.4 million (from million €86.6 to €67.2), due to the decrease of testing costs (by €17 million) and ancillary-care costs (by €2.4 million), even with an increase of the number of genetic counseling visits. The cost savings was € 40.49 per screened woman. The adoption of NIPT test, as a contingent screening for women with a trisomy risk ≥ 1:1,000 after standard of care screening, represents a benefit for the mother and fetus with the possibility of avoiding invasive diagnostic testing. Therefore, for both clinical and economic reasons, the adoption of NIPT under a reimbursement setting would be a cost-saving choice.

First-Trimester Contingent Screening for Trisomy 21 by Fetal Nuchal Translucency and Maternal Serum Biomarkers and Maternal Blood Cell-Free DNA Testing

AbstractAnalysis of cell-free DNA in maternal blood has been proposed as a novel screening method for evaluation of aneuploidies. The higher performance of this technique in screening of trisomies compared to all currently available methods would lead to widespread use of this technique in clinical settings. In total, 1,066,829 singleton pregnancies referred to Nilou Clinical Laboratory were screened for chromosomal trisomies during a period of 12 years. First-trimester screening (FTS), Triple and Quad markers of second-trimester screening (STS) as well as integrated results have been obtained from 444,515, 34,984, 560,857 and 26,473 singleton pregnancies respectively. Non-invasive prenatal test (NIPT) using cfDNA was applied in 3500 pregnant women. Risk cutoffs, detection rates (DRs) and false positive rates (FPRs) were assessed for combinations of screening strategies to identify the most efficient strategy for contingent cfDNA testing. Contingent screening including FTS and NIPT offer to 20% of cases would lead to detection of 98% of fetuses with trisomy 21 at a total invasive testing rate of 1.1%. Contingent screening including STS and NIPT offer to 9.0% of cases would lead to detection of 95.5% of fetuses with trisomy 21 at a total invasive testing rate of 4.5%. Contingent screening including FTS or STS and cfDNA testing are efficient strategies for screening of trisomy 21.

Culturally Contingent Electronic Word-of-Mouth Signaling and Screening: A Comparative Study of Product Reviews in the United States and Japan

Electronic word of mouth (eWOM) is an important source of influence on consumer decision making, yet little is known about cross-cultural differences in both the occurrence of eWOM and the relationship between eWOM and sales. The authors draw on signaling theory to develop a conceptual model and assess the relationships between country and the occurrence of eWOM, as well as between online ratings and relative product sales according to country. Online reviews and sales rank data for books, CDs, and DVDs were collected from Amazon U.S. and Amazon Japan in 2009 and 2017. Results suggest cross-national differences in both the occurrence of eWOM (eWOM signaling) and the relationship between eWOM and relative product sales (eWOM screening). These national differences appear to change over time: some remain stable, some disappear, and others emerge. The proposed culturally contingent signaling and screening model may be adopted as a framework for future research on cross-cultural eWOM. The results also inform the literature on cultural change by suggesting that cultural differences in eWOM change in nuanced patterns over time.