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KILINÇDEMİR Ü, SEZİK M. İlk trimester tarama testi risk kategorilerinin gebelik sonuçları ile ilişkisi The association between first trimester screening test risk category and pregnancy outcomes. KAHRAMANMARAŞ SÜTÇÜ İMAM ÜNIVERSITESI TIP FAKÜLTESI DERGISI 2020. [DOI: 10.17517/ksutfd.798187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Durković J, Ubavić M, Durković M, Kis T. Prenatal Screening Markers for Down Syndrome: Sensitivity, Specificity, Positive and Negative Expected Value Method. J Med Biochem 2018; 37:62-66. [PMID: 30581343 PMCID: PMC6294102 DOI: 10.1515/jomb-2017-0022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 04/13/2017] [Indexed: 11/21/2022] Open
Abstract
Background Genetic screening for chromosomopathy is performed in the first trimester of pregnancy by determining fetal nuchal translucency (NT), and the pregnancy associated plasma protein-A (PAPP-A) and free human chorionic gonadotropin (free-beta HCG) biomarkers in maternal serum. Methods We tested the sensitivity, specificity, positive and negative expected values of each marker with the aim of setting a model for prenatal screening readings. Statistical data treatment has been performed on a sample of 340 pregnant women with positive results of prenatal screening. Results Sensitivity of PAPP-A was 0.6250 (probability 62.50%), free beta HCG 0.5893 (58.93%), NT 0.1785 (17.85%). Specificity of PAPP-A was 0.5106 (probability 51.06%), free beta HCG 0.5246 (52.46%), NT 0.9718 (97.18%). Positive expected value of PAPP-A was 0.2011 (probability 20.11%), free beta HCG 0.1964 (19.64%), NT 0.556 (55.56%). Negative expected value of PAPP-A was 0.8735 (probability 87.35%), free beta HCG 0.8662 (86.62%), NT 0.8571 (85.71%). The NT marker has a significantly higher specificity, which means that its normal value will significantly reduce the final risk of trisomy 21. The sensitivity of NT is much lower than that of biochemical markers, which means that a pathological value of NT does not have a significant influence on the final risk, i.e. the significantly higher sensitivity of biochemical markers will reduce the final risk of trisomy 21. Conclusions The analyses stress the importance of using a software which has the possibility to separate the level of a biochemical risk by correlating PAPP-A and free beta HCG and, by adding the NT marker, calculate the level of a final risk of Down syndrome.
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Affiliation(s)
| | | | - Milica Durković
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Tibor Kis
- Faculty of Economics, Subotica, Serbia
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Alldred SK, Takwoingi Y, Guo B, Pennant M, Deeks JJ, Neilson JP, Alfirevic Z. First trimester ultrasound tests alone or in combination with first trimester serum tests for Down's syndrome screening. Cochrane Database Syst Rev 2017; 3:CD012600. [PMID: 28295158 PMCID: PMC6464518 DOI: 10.1002/14651858.cd012600] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Down's syndrome occurs when a person has three, rather than two copies of chromosome 21; or the specific area of chromosome 21 implicated in causing Down's syndrome. It is the commonest congenital cause of mental disability and also leads to numerous metabolic and structural problems. It can be life-threatening, or lead to considerable ill health, although some individuals have only mild problems and can lead relatively normal lives. Having a baby with Down's syndrome is likely to have a significant impact on family life.Non-invasive screening based on biochemical analysis of maternal serum or urine, or fetal ultrasound measurements, allows estimates of the risk of a pregnancy being affected and provides information to guide decisions about definitive testing.Before agreeing to screening tests, parents need to be fully informed about the risks, benefits and possible consequences of such a test. This includes subsequent choices for further tests they may face, and the implications of both false positive and false negative screening tests (i.e. invasive diagnostic testing, and the possibility that a miscarried fetus may be chromosomally normal). The decisions that may be faced by expectant parents inevitably engender a high level of anxiety at all stages of the screening process, and the outcomes of screening can be associated with considerable physical and psychological morbidity. No screening test can predict the severity of problems a person with Down's syndrome will have. OBJECTIVES To estimate and compare the accuracy of first trimester ultrasound markers alone, and in combination with first trimester serum tests for the detection of Down's syndrome. SEARCH METHODS We carried out extensive literature searches including MEDLINE (1980 to 25 August 2011), Embase (1980 to 25 August 2011), BIOSIS via EDINA (1985 to 25 August 2011), CINAHL via OVID (1982 to 25 August 2011), and The Database of Abstracts of Reviews of Effects (the Cochrane Library 2011, Issue 7). We checked reference lists and published review articles for additional potentially relevant studies. SELECTION CRITERIA Studies evaluating tests of first trimester ultrasound screening, alone or in combination with first trimester serum tests (up to 14 weeks' gestation) for Down's syndrome, compared with a reference standard, either chromosomal verification or macroscopic postnatal inspection. DATA COLLECTION AND ANALYSIS Data were extracted as test positive/test negative results for Down's and non-Down's pregnancies allowing estimation of detection rates (sensitivity) and false positive rates (1-specificity). We performed quality assessment according to QUADAS criteria. We used hierarchical summary ROC meta-analytical methods to analyse test performance and compare test accuracy. Analysis of studies allowing direct comparison between tests was undertaken. We investigated the impact of maternal age on test performance in subgroup analyses. MAIN RESULTS We included 126 studies (152 publications) involving 1,604,040 fetuses (including 8454 Down's syndrome cases). Studies were generally good quality, although differential verification was common with invasive testing of only high-risk pregnancies. Sixty test combinations were evaluated formed from combinations of 11 different ultrasound markers (nuchal translucency (NT), nasal bone, ductus venosus Doppler, maxillary bone length, fetal heart rate, aberrant right subclavian artery, frontomaxillary facial angle, presence of mitral gap, tricuspid regurgitation, tricuspid blood flow and iliac angle 90 degrees); 12 serum tests (inhibin A, alpha-fetoprotein (AFP), free beta human chorionic gonadotrophin (ßhCG), total hCG, pregnancy-associated plasma protein A (PAPP-A), unconjugated oestriol (uE3), disintegrin and metalloprotease 12 (ADAM 12), placental growth factor (PlGF), placental growth hormone (PGH), invasive trophoblast antigen (ITA) (synonymous with hyperglycosylated hCG), growth hormone binding protein (GHBP) and placental protein 13 (PP13)); and maternal age. The most frequently evaluated serum markers in combination with ultrasound markers were PAPP-A and free ßhCG.Comparisons of the 10 most frequently evaluated test strategies showed that a combined NT, PAPP-A, free ßhCG and maternal age test strategy significantly outperformed ultrasound markers alone (with or without maternal age) except nasal bone, detecting about nine out of every 10 Down's syndrome pregnancies at a 5% false positive rate (FPR). In both direct and indirect comparisons, the combined NT, PAPP-A, free ßhCG and maternal age test strategy showed superior diagnostic accuracy to an NT and maternal age test strategy (P < 0.0001). Based on the indirect comparison of all available studies for the two tests, the sensitivity (95% confidence interval) estimated at a 5% FPR for the combined NT, PAPP-A, free ßhCG and maternal age test strategy (69 studies; 1,173,853 fetuses including 6010 with Down's syndrome) was 87% (86 to 89) and for the NT and maternal age test strategy (50 studies; 530,874 fetuses including 2701 Down's syndrome pregnancies) was 71% (66 to 75). Combinations of NT with other ultrasound markers, PAPP-A and free ßhCG were evaluated in one or two studies and showed sensitivities of more than 90% and specificities of more than 95%.High-risk populations (defined before screening was done, mainly due to advanced maternal age of 35 years or more, or previous pregnancies affected with Down's syndrome) showed lower detection rates compared to routine screening populations at a 5% FPR. Women who miscarried in the over 35 group were more likely to have been offered an invasive test to verify a negative screening results, whereas those under 35 were usually not offered invasive testing for a negative screening result. Pregnancy loss in women under 35 therefore leads to under-ascertainment of screening results, potentially missing a proportion of affected pregnancies and affecting test sensitivity. Conversely, for the NT, PAPP-A, free ßhCG and maternal age test strategy, detection rates and false positive rates increased with maternal age in the five studies that provided data separately for the subset of women aged 35 years or more. AUTHORS' CONCLUSIONS Test strategies that combine ultrasound markers with serum markers, especially PAPP-A and free ßhCG, and maternal age were significantly better than those involving only ultrasound markers (with or without maternal age) except nasal bone. They detect about nine out of 10 Down's affected pregnancies for a fixed 5% FPR. Although the absence of nasal bone appeared to have a high diagnostic accuracy, only five out of 10 affected Down's pregnancies were detected at a 1% FPR.
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Affiliation(s)
- S Kate Alldred
- The University of LiverpoolDepartment of Women's and Children's HealthFirst Floor, Liverpool Women's NHS Foundation TrustCrown StreetLiverpoolUKL8 7SS
| | - Yemisi Takwoingi
- University of BirminghamInstitute of Applied Health ResearchEdgbastonBirminghamUKB15 2TT
| | - Boliang Guo
- University of NottinghamSchool of MedicineCLAHRC, C floor, IHM, Jubilee CampusUniversity of Nottingham, Triumph RoadNottinghamEast MidlandsUKNG7 2TU
| | - Mary Pennant
- Cambridgeshire County CouncilPublic Health DirectorateCambridgeUK
| | - Jonathan J Deeks
- University of BirminghamInstitute of Applied Health ResearchEdgbastonBirminghamUKB15 2TT
| | | | - Zarko Alfirevic
- The University of LiverpoolDepartment of Women's and Children's HealthFirst Floor, Liverpool Women's NHS Foundation TrustCrown StreetLiverpoolUKL8 7SS
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Rosignoli L, Tonni G. Should cell-free fetal DNA be included in first trimester screening (FTS) for common trisomy? A possible scenario on 6697 women screened over 10 years. J Eval Clin Pract 2016; 22:899-906. [PMID: 27345561 DOI: 10.1111/jep.12557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 04/06/2016] [Accepted: 04/06/2016] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The primary aim was to determine the performance of the first trimester screening (FTS) test in a general obstetrics population. Cost-benefit analysis of a hypothetic model based on implementation of the FTS test by cell-free fetal (cff) DNA was calculated. METHODS A total of 6697 women were screened using FTS test. A two-step strategy based upon nuchal translucency, serum screening and ultrasound assessment of nasal bone (NB) was applied. Three groups were identified (high-risk: >1:250; intermediate-risk: 1:251-1:999 and low-risk group: <1:1000). Women at intermediate-risk (1:251-1:999) underwent NB assessment and recalculation of individual risk. All women at high-risk were offered fetal karyotyping. RESULTS A total of 321 women (4.8%) resulted at high-risk while 480 women (7.1%) with intermediate-risk underwent assessment of the NB, which was absent in 15 fetuses. Overall, 54 aneuploidies were detected for a 96.4% sensitivity, a 96.1% specificity, a 99.9% negative predictive value and a false positive rate of 4.8%. Audit was conducted on a yearly basis and lost to follow up was 0.47% (32 cases). CONCLUSIONS Public health system would not be able to cover the cost of including cff DNA in women undergoing first trimester screening on universal basis. However, assuming a possible scenario based on implementation of FTS by cff DNA in women at high-risk would result in a 6-fold reduction in the number of invasive procedures while avoiding two false negative results (trisomy 21) that were diagnosed in women with intermediate-risk using current screening strategy by combined test.
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Affiliation(s)
- Lucia Rosignoli
- Center for Prevention of Fetal Malformations, Department of Obstetrics and Gynecology, Hospital Meyer, Florence, Italy
| | - Gabriele Tonni
- Prenatal Diagnostic Center, Department of Obstetrics and Gynecology, Guastalla Civil Hospital, AUSL Reggio Emilia, Reggio Emilia, Italy
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Alldred SK, Takwoingi Y, Guo B, Pennant M, Deeks JJ, Neilson JP, Alfirevic Z. First trimester serum tests for Down's syndrome screening. Cochrane Database Syst Rev 2015; 2015:CD011975. [PMID: 26617074 PMCID: PMC6465076 DOI: 10.1002/14651858.cd011975] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Down's syndrome occurs when a person has three, rather than two copies of chromosome 21; or the specific area of chromosome 21 implicated in causing Down's syndrome. It is the commonest congenital cause of mental disability and also leads to numerous metabolic and structural problems. It can be life-threatening, or lead to considerable ill health, although some individuals have only mild problems and can lead relatively normal lives. Having a baby with Down's syndrome is likely to have a significant impact on family life.Noninvasive screening based on biochemical analysis of maternal serum or urine, or fetal ultrasound measurements, allows estimates of the risk of a pregnancy being affected and provides information to guide decisions about definitive testing. However, no test can predict the severity of problems a person with Down's syndrome will have. OBJECTIVES The aim of this review was to estimate and compare the accuracy of first trimester serum markers for the detection of Down's syndrome in the antenatal period, both as individual markers and as combinations of markers. Accuracy is described by the proportion of fetuses with Down's syndrome detected by screening before birth (sensitivity or detection rate) and the proportion of women with a low risk (normal) screening test result who subsequently had a baby unaffected by Down's syndrome (specificity). SEARCH METHODS We conducted a sensitive and comprehensive literature search of MEDLINE (1980 to 25 August 2011), Embase (1980 to 25 August 2011), BIOSIS via EDINA (1985 to 25 August 2011), CINAHL via OVID (1982 to 25 August 2011), The Database of Abstracts of Reviews of Effectiveness (The Cochrane Library 25 August 2011), MEDION (25 August 2011), The Database of Systematic Reviews and Meta-Analyses in Laboratory Medicine (25 August 2011), The National Research Register (Archived 2007), Health Services Research Projects in Progress database (25 August 2011). We did forward citation searching ISI citation indices, Google Scholar and PubMed 'related articles'. We did not apply a diagnostic test search filter. We also searched reference lists and published review articles. SELECTION CRITERIA We included studies in which all women from a given population had one or more index test(s) compared to a reference standard (either chromosomal verification or macroscopic postnatal inspection). Both consecutive series and diagnostic case-control study designs were included. Randomised trials where individuals were randomised to different screening strategies and all verified using a reference standard were also eligible for inclusion. Studies in which test strategies were compared head-to-head either in the same women, or between randomised groups were identified for inclusion in separate comparisons of test strategies. We excluded studies if they included less than five Down's syndrome cases, or more than 20% of participants were not followed up. DATA COLLECTION AND ANALYSIS We extracted data as test positive or test negative results for Down's and non-Down's pregnancies allowing estimation of detection rates (sensitivity) and false positive rates (1-specificity). We performed quality assessment according to QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria. We used hierarchical summary ROC meta-analytical methods or random-effects logistic regression methods to analyse test performance and compare test accuracy as appropriate. Analyses of studies allowing direct and indirect comparisons between tests were undertaken. MAIN RESULTS We included 56 studies (reported in 68 publications) involving 204,759 pregnancies (including 2113 with Down's syndrome). Studies were generally of good quality, although differential verification was common with invasive testing of only high-risk pregnancies. We evaluated 78 test combinations formed from combinations of 18 different tests, with or without maternal age; ADAM12 (a disintegrin and metalloprotease), AFP (alpha-fetoprotein), inhibin, PAPP-A (pregnancy-associated plasma protein A, ITA (invasive trophoblast antigen), free βhCG (beta human chorionic gonadotrophin), PlGF (placental growth factor), SP1 (Schwangerschafts protein 1), total hCG, progesterone, uE3 (unconjugated oestriol), GHBP (growth hormone binding protein), PGH (placental growth hormone), hyperglycosylated hCG, ProMBP (proform of eosinophil major basic protein), hPL (human placental lactogen), (free αhCG, and free ßhCG to AFP ratio. Direct comparisons between two or more tests were made in 27 studies.Meta-analysis of the nine best performing or frequently evaluated test combinations showed that a test strategy involving maternal age and a double marker combination of PAPP-A and free ßhCG significantly outperformed the individual markers (with or without maternal age) detecting about seven out of every 10 Down's syndrome pregnancies at a 5% false positive rate (FPR). Limited evidence suggested that marker combinations involving PAPP-A may be more sensitive than those without PAPP-A. AUTHORS' CONCLUSIONS Tests involving two markers in combination with maternal age, specifically PAPP-A, free βhCG and maternal age are significantly better than those involving single markers with and without age. They detect seven out of 10 Down's affected pregnancies for a fixed 5% FPR. The addition of further markers (triple tests) has not been shown to be statistically superior; the studies included are small with limited power to detect a difference.The screening blood tests themselves have no adverse effects for the woman, over and above the risks of a routine blood test. However some women who have a 'high risk' screening test result, and are given amniocentesis or chorionic villus sampling (CVS) have a risk of miscarrying a baby unaffected by Down's. Parents will need to weigh up this risk when deciding whether or not to have an amniocentesis or CVS following a 'high risk' screening test result.
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Affiliation(s)
- S Kate Alldred
- The University of LiverpoolDepartment of Women's and Children's HealthFirst Floor, Liverpool Women's NHS Foundation TrustCrown StreetLiverpoolUKL8 7SS
| | - Yemisi Takwoingi
- University of BirminghamPublic Health, Epidemiology and BiostatisticsEdgbastonBirminghamUKB15 2TT
| | - Boliang Guo
- University of NottinghamSchool of MedicineCLAHRC, C floor, IHM, Jubilee CampusUniversity of Nottingham, Triumph RoadNottinghamEast MidlandsUKNG7 2TU
| | - Mary Pennant
- Cambridgeshire County CouncilPublic Health DirectorateCambridgeUK
| | - Jonathan J Deeks
- University of BirminghamPublic Health, Epidemiology and BiostatisticsEdgbastonBirminghamUKB15 2TT
| | - James P Neilson
- The University of LiverpoolDepartment of Women's and Children's HealthFirst Floor, Liverpool Women's NHS Foundation TrustCrown StreetLiverpoolUKL8 7SS
| | - Zarko Alfirevic
- The University of LiverpoolDepartment of Women's and Children's HealthFirst Floor, Liverpool Women's NHS Foundation TrustCrown StreetLiverpoolUKL8 7SS
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Lee FK, Chen LC, Cheong ML, Chou CY, Tsai MS. First trimester combined test for Down syndrome screening in unselected pregnancies — A report of a 13-year experience. Taiwan J Obstet Gynecol 2013; 52:523-6. [DOI: 10.1016/j.tjog.2013.10.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 10/30/2012] [Indexed: 11/29/2022] Open
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Bueno JAS, García M, Fernández A, Turmo E, Garrido R. New contingent sequential screening model for Down syndrome based on the combined test associated with modified genetic sonography. J Matern Fetal Neonatal Med 2013; 26:1792-8. [PMID: 23713967 DOI: 10.3109/14767058.2013.806895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The aim of this study is to evaluate the possibility of implementing a contingent sequential screening test for Down syndrome (DS) based on the combined test (CT) associated with modified genetic sonography (MGS). We evaluate sensitivity (Sen), false positive rate (FPR), and economic costs. METHOD We compiled data from the results of a prospective screening programme for DS during a 5-year study period (July 2005-December 2011). Pregnancies were offered the CT as the first step in the contingent sequential test. We identified an intermediate risk group (1/101-1/1000) using CT results, and offered these individuals a MGS (major malformation and nuchal fold). RESULTS A total of 19 440 pregnancies (103 chromosome abnormalities and 66 cases of DS) were administered the CT. We performed a MGS on 99.6% of individuals in the intermediate risk group (2188/2197); in this group, we observed 22 chromosome abnormalities (17 DS). The CT provided a Sen for DS of 80.30% (95%CI: 68.68-89.07) (53/66), and a Sen for all chromosome abnormalities of 76.70% (95%CI: 67.34-84.46) (79/103), with a FPR of 3.79% (95%CI: 3.52-4.05) (732/19 374). The contingent sequential strategy produced a Sen for DS of 81.82% (95%CI: 70.39-90.24) (54/66) and a Sen for all chromosome abnormalities of 79.61% (95%CI: 70.54-86.91) (82/103), with a FPR of 1.16% (95%CI: 1.02-1.33) (224/19 457). The economic costs of the CT and the contingent sequential model were 9 70 275 Euros and 9 41 716 Euros, respectively. CONCLUSIONS We present a new sequential contingent strategy for DS screening and demonstrate its usefulness for reducing FPR while maintaining a high level of Sen for DS, without requiring an increase in economic costs.
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Sainz JA, Serrano R, Borrero C, Turmo E. First trimester contingent test as a screening method for Down's syndrome. A prospective study in the general population. J Matern Fetal Neonatal Med 2012; 25:2221-4. [PMID: 22524587 DOI: 10.3109/14767058.2012.684168] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES To evaluate the possibility of implementing a contingent test as a screening method for Down's syndrome (DS) in the first trimester of pregnancy, and assess its sensitivity (Sen) and false positive rate (FPR). METHODS Prospective study covering a 4-year study period (July 2006-June 2010). Pregnant women were offered a combined test (CT) as the first step of a contingent test. An intermediate risk group is identified in the CT (1/101 and 1/1000) and offered an ultrasound assessment of secondary s (nasal bone, ductus venosus, tricuspid regurgitation). RESULTS CTs were performed on 10,452 pregnant women (24 cases of DS). In the intermediate risk group, which had 7 cases of DS, we performed secondary ultrasound marker assessment on 98.1% (1,017/1,036). The CT and the contingent test had a Sen of 83% (95% CI; 67.9-98) (20/24) and 70.8% (95% CI; 52.6-88.9) (17/24) with an FPR of 3% (95% CI; 2.7-3.3) (316/10,430) and 2% (95% CI; 1.7-2.3) (220/10,408), respectively. CONCLUSIONS With the contingent test, we managed to reduce the FPR, but the Sen was too low for use as a screening method for DS.
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Affiliation(s)
- José A Sainz
- Department of Obstetrics and Gynaecology, Valme University Hospital, Seville, Spain.
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Muñoz-Cortes M, Arigita M, Falguera G, Seres A, Guix D, Baldrich E, Acera A, Torrent A, Rodriguez-Veret A, Lopez-Quesada E, Garcia-Moreno R, Gonce A, Borobio V, Borrell A. Contingent screening for Down syndrome completed in the first trimester: a multicenter study. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2012; 39:396-400. [PMID: 21674658 DOI: 10.1002/uog.9075] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
OBJECTIVE To assess a new contingent screening strategy for Down syndrome completed in the first trimester. METHODS First-trimester screening combining nuchal translucency thickness measurement and assessment of serum analytes (combined test) was offered to pregnant women who presented for prenatal care during the first trimester to nine health centers and community hospitals in the area served by the Catalan Public Health Service. If an intermediate risk (1/101-1/1000) for Down syndrome was identified, women were referred to the Hospital Clinic Barcelona for risk reassessment that included the use of secondary ultrasound markers (nasal bone, ductus venosus blood flow and tricuspid flow). Intermediate-risk women were divided into two subgroups for further analysis: high-intermediate risk (1/101-1/250) and low-intermediate risk (1/251-1/1000). We compared feasibility and efficacy of both combined and contingent screening strategies. RESULTS The combined test, the first screening stage, was performed in 16 001 pregnant women, of whom 1617 (10.1%) were found to have an intermediate risk. Further division of this group showed that 1.8% (n = 289) of women were at high-intermediate risk and 8.3% (n = 1328) at low-intermediate risk. The contingent screening strategy significantly reduced the false-positive rate, from 3.0% to 1.3-1.8% (P < 0.001), without affecting the detection rate (which was 75-79% and 76%, with and without the contingent screening strategy, respectively). However, only 45% of intermediate-risk patients underwent the second screening step due to a preference among high-intermediate-risk (1/101-1/250) women for invasive testing and to low uptake among low-intermediate-risk (1/251-1/1000) women. CONCLUSIONS The proposed first-trimester contingent strategy reduces the screen false-positive rate without impacting on the detection rate of Down syndrome. The low compliance observed in our study may prevent its use in certain populations.
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Affiliation(s)
- M Muñoz-Cortes
- Prenatal Diagnosis Unit, Hospital Clinic de Barcelona, Barcelona, Catalonia, Spain
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Singh Sahota D, Leung WC, Kee To W, Pan Chan W, Lau TK, Yeung Leung T. Quality assurance of nuchal translucency for prenatal fetal Down syndrome screening. J Matern Fetal Neonatal Med 2011; 25:1039-43. [DOI: 10.3109/14767058.2011.614658] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Sahota DS, Chen M, Leung TY, Chan LW, Fung TY, Ting YH, Lau TK. Assessment of sonographer nuchal translucency measurement performance – central tendency and dispersion. J Matern Fetal Neonatal Med 2011; 24:812-6. [DOI: 10.3109/14767058.2010.531310] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Affiliation(s)
- Kypros H Nicolaides
- Harris Birthright Research Centre for Fetal Medicine, King's College Hospital,London, UK and Department of Fetal Medicine, University College Hospital, London, UK.
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Kagan KO, Staboulidou I, Cruz J, Wright D, Nicolaides KH. Two-stage first-trimester screening for trisomy 21 by ultrasound assessment and biochemical testing. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2010; 36:542-547. [PMID: 20503223 DOI: 10.1002/uog.7663] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
OBJECTIVES This study was carried out to examine the performance of a contingent policy in first-trimester screening for trisomy 21, in which the estimated risk was first derived by a combination of maternal age, fetal nuchal translucency (NT) thickness, presence/absence of the nasal bone, blood flow in the ductus venosus or flow across the tricuspid valve, and biochemical testing was carried out only in those who were found to have an intermediate risk. We also examined the performance of a policy in which the estimated risk was first derived by a combination of maternal age and biochemical testing, and ultrasound examination was carried out only in those with an intermediate risk. METHODS The data for this study were derived from prospective screening for trisomy 21 in singleton pregnancies, using, as markers, a combination of maternal age, fetal NT thickness and maternal-serum free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A), in a one-stop clinic for first-trimester assessment of risk at 11 + 0 to 13 + 6 weeks of gestation. Assessment of the fetal nasal bone, ductus venosus flow and tricuspid flow were also routinely performed by appropriately trained sonographers. The performance of different screening policies was examined. RESULTS The study population consisted of 19 614 pregnancies with a normal karyotype or delivery of a phenotypically normal baby (euploid group) and 122 cases of trisomy 21. The best performance was achieved by a contingent policy in which first-stage screening was based on maternal age, fetal NT thickness and either tricuspid valve or ductus venosus blood flow, followed by biochemical testing only those with an intermediate risk, of 1 in 51 to 1 in 1000 (which constituted about 20% of the total). The performance of contingent screening in which first-stage testing relies on biochemistry was poorer than when first-stage screening was performed by ultrasound examination because, in order to achieve the same detection rate, the false-positive rate was twice as high. CONCLUSION Effective first-trimester screening for trisomy 21 can be achieved by a contingent policy in which first-stage testing is based on ultrasound examination and second-stage biochemical testing is carried out in only 20% of the patients.
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Affiliation(s)
- K O Kagan
- Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK
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Sahota DS, Leung TY, Chen M, Chan LW, Fung TY, Lau TK. Comparison of likelihood ratios of first-trimester nuchal translucency measurements: multiples of median, delta or mixture. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2010; 36:15-19. [PMID: 20503228 DOI: 10.1002/uog.7677] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
OBJECTIVE To compare the likelihood ratios (LR) determined for a measured nuchal translucency (NT) using the multiples of the median (MoM), delta-NT and mixture model approaches. METHODS This was a retrospective study of singleton pregnancies with known outcome screened at the 12(th) week of pregnancy between January 2006 and May 2008. NT, crown-rump length (CRL) and LR for trisomy 21 using the delta-NT approach (LRNT-delta) were extracted from The Fetal Medicine Foundation trisomy 21 risk-calculation software database. NT measurements were converted into their equivalent MoM by dividing by the expected CRL-specific median NT. LR for trisomy 21 based on the MoM (LRNT-MoM) of each case was then calculated as the ratio of the Gaussian probability density functions using published trisomy 21 risk-screening parameters. The LR using the mixture model (LRNT-mixture) was calculated as the ratio of individual composite probability densities reported for trisomy 21 and unaffected pregnancies. The intraclass correlation coefficient (ICC) was used to assess the agreement between the three different approaches while the paired t-test was used to perform pairwise comparisons. RESULTS Of the 5907 pregnancies with known outcome, 14 had trisomy 21. The ICC between the three approaches to determining an LR was 0.947 (95% CI, 0.943-0.951; P < 0.0001). Pairwise comparison indicated that differences between LR were statistically significant (P < 0.0001). Likelihood ratios determined via the delta-NT model were in general greater than those produced by both the mixture model (z = 5.58, P < 0.0001) and the MoM approaches (z = 32.8, P < 0.0001). For a 5% false-positive rate the detection rate of trisomy 21 (DR) was 78.6% (95% CI, 57.1-99.9%) The screen positive thresholds to achieve this DR were 1 : 200 for the delta-NT approach, 1 : 220 for the mixture approach and 1 : 290 for the MoM approach. CONCLUSION No single method of determining NT-associated LR outperformed the others in its ability to detect a trisomy 21-affected pregnancy.
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Affiliation(s)
- D S Sahota
- Department of Obstetrics and Gynaecology, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
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