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Sahota DS, Tsang FHK, Gu JS, Fung WKV, Mok KY, Wong CL. A technical and clinical evaluation of the new ThermoFisher BRAHMS unconjugated estriol and inhibin-A assays and their use in second trimester Down syndrome screening. Scandinavian Journal of Clinical and Laboratory Investigation 2021; 81:371-378. [PMID: 34060966 DOI: 10.1080/00365513.2021.1929439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
To evaluate second-trimester Down syndrome screening performance of the new ThermoFisher BRAHMS GOLD unconjugated estriol (uE3) and inhibin-A assays. Serum samples were analyzed for levels of uE3 and inhibin-A using the ThermoFisher BRAHMS GOLD immunoanalyzer and compared to other platforms. Levels were transformed to multiples of the median (MoM) in unaffected pregnancies. Log10 MoM distributions in unaffected and Down syndrome pregnancies were assessed for central tendency (mean) and dispersion (SD). Empirical and estimated screening performances were determined. Correlation between BRAHMS and AutoDELFIA® uE3 and inhibin-A were 0.63 and 0.97, respectively, the respective mean difference was 31.3% [95%CI 50.2% to -112.8%] and -23.3% [95%CI -41.9% to -4.7%]. Passing-Bablok indicated significant systematic (-2.78 [95%CI -3.57 to -2.04]) and proportional bias (1.30 [95%CI 1.15 to -1.47]) between uE3 assays and significant proportional bias (0.71[95%CI 0.65-0.78]) between inhibin-A assays. The uE3 and inhibin-A log10 MoM distribution mean [SD] in unaffected and Down syndrome pregnancies were 0.0024 [SD = 0.2341] and -0.0001 [SD = 0.2078], and -0.2028 [SD = 0.2495] and 0.3645 [SD = 0.2576], respectively. The new BRAHMS uE3 and inhibin-A assays had an 81-83% detection rate for Trisomy21 for a 5% false-positive rate. The new BRAHMS assays achieved the expected screening performance provided the risk estimation model is adjusted to account for the higher BRAHMS uE3 MoM measurement distribution variance.
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Affiliation(s)
- Daljit Singh Sahota
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Fanny Ho Kau Tsang
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Jia Shi Gu
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Wai Kei Vicky Fung
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Kit Yee Mok
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Chui Lin Wong
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
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Cheng Y, Leung TY, Law LW, Ting YH, Law KM, Sahota DS. First trimester screening for pre-eclampsia in Chinese pregnancies: case-control study. BJOG 2018; 125:442-449. [PMID: 29032578 DOI: 10.1111/1471-0528.14970] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2017] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To assess the potential of screening for pre-eclampsia (PE) in a Chinese population. DESIGN Case-control study. SETTING Teaching hospital in Hong Kong. POPULATION A total of 3330 women having a viable singleton pregnancy attending first-trimester Down-syndrome screening. METHODS Mean arterial pressure (MAP), bilateral uterine artery pulsatility index (UtA-PI), and placental growth factor (PlGF) were measured. Screening markers were transformed to multiples of the gestational median (MoM) and adjusted for maternal and pregnancy characteristics. MoM distributions in PE and non-PE pregnancies were compared with published expected values. PE screening performance was assessed using area under receiver operating curves (AUROC). MAIN OUTCOME MEASURES PE detection rate. RESULTS A total of 30 (0.9%) women developed either early (<34 weeks) or late (≥34 weeks) onset PE. MAP was dependent on maternal BMI, UtA-PI on fetal crown rump length, uterine artery peak systolic velocity (UtA-PSV) on maternal age and gestation, and PlGF on gestation in non-PE pregnancies. MoM distributions determined using published Fetal Medicine Foundation models deviated significantly from one for both MAP (P < 0.0001) and PI (P < 0.0001), but not PlGF (P = 0.52) in non-PE pregnancies, whilst PlGF MoM distributions in those who developed early as opposed to late onset PE were significantly higher (P = <0.05). AUROC for any PE using multiple markers was 0.72 (95% CI: 0.64-0.81) with detection rates of 72 and 55% for early and late PE, respectively, for a 10% false positive rate. CONCLUSION Detection rates for PE in our Chinese population were lower than the expected 90-95% even after adjusting MoM for local women's characteristics. FUNDING General Research Fund (Project number 470513). TWEETABLE ABSTRACT Pre-eclampsia screening in the Chinese population had detection rates lower than previously published results.
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Affiliation(s)
- Yky Cheng
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - T Y Leung
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - L W Law
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Y H Ting
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - K M Law
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - D S Sahota
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
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Chaemsaithong P, Ting YH, Cheng KYY, Poon CYL, Leung TY, Sahota DS. Uterine artery pulsatility index in the first trimester: assessment of intersonographer and intersampling site measurement differences. J Matern Fetal Neonatal Med 2017; 31:2276-2283. [DOI: 10.1080/14767058.2017.1341481] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Piya Chaemsaithong
- Department of Obstetrics and Gynecology, the Chinese University of Hong Kong, Hong Kong SAR, China
| | - Yuen Ha Ting
- Department of Obstetrics and Gynecology, the Chinese University of Hong Kong, Hong Kong SAR, China
| | - Kwun Yue Yvonne Cheng
- Department of Obstetrics and Gynecology, the Chinese University of Hong Kong, Hong Kong SAR, China
| | - Chiu Yee Liona Poon
- Department of Obstetrics and Gynecology, the Chinese University of Hong Kong, Hong Kong SAR, China
| | - Tak Yeung Leung
- Department of Obstetrics and Gynecology, the Chinese University of Hong Kong, Hong Kong SAR, China
| | - Daljit Singh Sahota
- Department of Obstetrics and Gynecology, the Chinese University of Hong Kong, Hong Kong SAR, China
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Li B, Sahota DS, Lao TT, Xu J, Hu SQ, Zhang L, Liu QY, Sun Q, Tang D, Ma RM. Applicability of first-trimester combined screening for fetal trisomy 21 in a resource-limited setting in mainland China. BJOG 2016; 123 Suppl 3:23-9. [PMID: 27627592 DOI: 10.1111/1471-0528.14004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2016] [Indexed: 11/29/2022]
Affiliation(s)
- B Li
- Department of Obstetrics and Gynaecology; The First Affiliated Hospital of Kunming Medical University; Kunming Yunnan China
| | - DS Sahota
- Department of Obstetrics and Gynaecology; The Chinese University of Hong Kong; Prince of Wales Hospital; Hong Kong SAR China
| | - TT Lao
- Department of Obstetrics and Gynaecology; The Chinese University of Hong Kong; Prince of Wales Hospital; Hong Kong SAR China
| | - J Xu
- Department of Obstetrics and Gynaecology; The First Affiliated Hospital of Kunming Medical University; Kunming Yunnan China
| | - SQ Hu
- Department of Obstetrics and Gynaecology; The First Affiliated Hospital of Kunming Medical University; Kunming Yunnan China
| | - L Zhang
- Department of Obstetrics and Gynaecology; The First Affiliated Hospital of Kunming Medical University; Kunming Yunnan China
| | - QY Liu
- Department of Obstetrics and Gynaecology; The First Affiliated Hospital of Kunming Medical University; Kunming Yunnan China
| | - Q Sun
- Department of Obstetrics and Gynaecology; The First Affiliated Hospital of Kunming Medical University; Kunming Yunnan China
| | - D Tang
- Department of Obstetrics and Gynaecology; The First Affiliated Hospital of Kunming Medical University; Kunming Yunnan China
| | - RM Ma
- Department of Obstetrics and Gynaecology; The First Affiliated Hospital of Kunming Medical University; Kunming Yunnan China
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Hermann M, Fries N, Mangione R, Boukobza P, Ville Y, Salomon LJ. Nuchal translucency measurement: are qualitative and quantitative quality control processes related? Prenat Diagn 2013; 33:770-4. [DOI: 10.1002/pd.4121] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/10/2013] [Accepted: 03/21/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Monika Hermann
- Department of Obstetrics and Gynecology; Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris; Paris France
- Société Française pour l'Amélioration des Pratiques Echographiques (SFAPE); Paris France
- Université Paris Descartes; Paris France
| | - Nicolas Fries
- Collège Français d'Echographie Fœtale (CFEF); France
| | | | | | - Yves Ville
- Department of Obstetrics and Gynecology; Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris; Paris France
- Société Française pour l'Amélioration des Pratiques Echographiques (SFAPE); Paris France
- Université Paris Descartes; Paris France
| | - Laurent J. Salomon
- Department of Obstetrics and Gynecology; Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris; Paris France
- Société Française pour l'Amélioration des Pratiques Echographiques (SFAPE); Paris France
- Université Paris Descartes; Paris France
- Collège Français d'Echographie Fœtale (CFEF); France
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Salomon LJ, Porcher R, Stirnemann JJ, Bernard JP, Ville Y. Likelihood ratio-based quality control for nuchal translucency measurements at 11-14 weeks of gestation. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2011; 37:576-581. [PMID: 20814879 DOI: 10.1002/uog.8811] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/20/2010] [Indexed: 05/29/2023]
Abstract
OBJECTIVE To develop a quantitative quality control process of nuchal translucency (NT) measurement at 11-14 weeks of gestation based on the mixture model, characterized by analysis of the corresponding distribution of the likelihood ratio (LR). METHODS Based on the published mixture model for NT measurement in the first trimester, we simulated the expected distribution of NT and the corresponding LR. This approach was then tested for the quality control of 15 048 NT measurements performed by four operators trained and certified by The Fetal Medicine Foundation. The new quality control approach based on LR was compared with existing processes based on NT plots, multiples of the median (MoMs) and analysis of the 95(th) centile. RESULTS Each operator contributed 2176-4730 examinations. Median, 5(th) and 95(th) centile of NT values ranged from 1.4 to 1.6, 1.0 to 1.0 and 2.2 to 2.6 mm, respectively. Median of NT-MoM values ranged from 0.83 to 0.95. Analysis of the distribution of NT measurements confirmed departure from the assumptions of the delta-NT and NT-MoM models. Analysis of LR distributions demonstrated a significant difference between observed and expected distributions for all operators (P < 10(-4) ). CONCLUSION An LR-based quality control process is feasible at 11-14 weeks of gestation. Because it is more sensitive to measurement bias around the critical area of the 95(th) centile, its use should be encouraged.
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Affiliation(s)
- L J Salomon
- Obstetrics and Maternal-Fetal Medicine, GHU Necker-Enfants Malades, AP-HP, Université Paris Descartes, Paris, France.
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Sennels HP, Jørgensen FS, Sørensen S. Biological variation of free β chorionic gonadotropin and pregnancy-associated plasma protein A in first trimester pregnancies. Clin Chem Lab Med 2010; 49:291-5. [PMID: 21091265 DOI: 10.1515/cclm.2011.054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Trisomy 21 risk estimation in first trimester pregnancies can be performed by a combined test based on ultrasound measurement of fetal nuchal translucency thickness and maternal plasma concentrations of free β human chorionic gonadotropin (hCGβ) and pregnancy-associated plasma protein A (PAPP-A). However, little knowledge exists regarding the biological variation of hCGβ and PAPP-A when the time interval between sampling increases. METHODS We estimated these variations from double measurements of hCGβ and PAPP-A in first trimester pregnancies in 167 women. Data were divided into three groups based on the number of days between sampling. The correlation coefficients and biological variation were estimated for each group. RESULTS The correlation coefficient between the first and second samples was 0.841 for hCGβ, and 0.706 for PAPP-A. The ranges for biological variation were 11.9%-48.5% for hCGβ and 31.6%-63.3% for PAPP-A, increasing with time between sampling. The average overall biological variation for hCGβ was 29%, and 49.7% for PAPP-A. CONCLUSIONS We found high biological variation for plasma concentrations of hCGβ and PAPP-A, increasing with longer time intervals between sampling. From our data that showed high correlation of hCGβ and PAPP-A in the first and second sample, we found no reason to recommend retesting. However, new studies should clarify whether PAPP-A should be collected early, and hCGβ late, in the first trimester of pregnancy.
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Affiliation(s)
- Henriette P Sennels
- Department of Clinical Biochemistry, Hvidovre Hospital, University of Copenhagen, Denmark.
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Christiansen M, Pihl K, Hedley PL, Gjerris AC, Lind PØ, Larsen SO, Krebs L, Larsen T. ADAM 12 may be used to reduce the false positive rate of first trimester combined screening for Down syndrome. Prenat Diagn 2010; 30:110-4. [PMID: 20013872 DOI: 10.1002/pd.2405] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND ADAM12 has been shown to be an efficient maternal serum marker for Down syndrome (DS) in the first trimester; but recent studies, using a second generation assay, have not confirmed these findings. We examined the efficiency of a second generation assay for ADAM12. MATERIALS AND METHODS ADAM12 concentrations were determined in 28 first trimester DS and 503 control pregnancies using a novel Research Delfia ADAM12 kit. Log10MoM distributions of ADAM12 and correlations with other markers were established. Population performance of screening was estimated by Monte Carlo simulation. RESULTS ADAM12 was significantly reduced in the first trimester in DS pregnancies with a log10MoM of -0.1621 (equivalent to 0.68 MoM) (p < 0.001). The reduction decreased with advancing gestational age. ADAM12 used with PAPP-A + hCG beta + NT (CUB screening) increased the detection rate (DR) from 86% to 89% for a false positive rate (FPR) of 5%. When used for a fixed DR of 90%, the addition of ADAM12 resulted in a 25% reduction of the FPR. CONCLUSION ADAM12 is a moderately effective DS marker. It is not a cost-effective addition to CUB screening, but may be used to reduce the FPR in selected high-risk cases.
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Affiliation(s)
- Michael Christiansen
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark.
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Wøjdemann KR, Larsen SO, Rode L, Shalmi A, Sundberg K, Christiansen M, Tabor A. First trimester Down syndrome screening: Distribution of markers and comparison of assays for quantification of pregnancy‐associated plasma protein‐A. Scandinavian Journal of Clinical and Laboratory Investigation 2009; 66:101-11. [PMID: 16537243 DOI: 10.1080/00365510500406902] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE First trimester screening for fetal chromosomal disease is now possible using the maternal serological markers pregnancy-associated plasma protein-A (PAPP-A) and the free ss-form of human chorionic gonadotrophin (sshCG) in combination with the ultrasound marker nuchal translucency (NT) thickness. The availability of well-defined analytical methods and reference ranges for the involved parameters, and knowledge of the correlation between markers and clinical parameters, e.g. maternal weight, parity and age, are important for the design of efficient screening programs. MATERIAL AND METHODS Women (n = 2702), with singleton pregnancies, participating in the Copenhagen First Trimester Screening Study had PAPP-A and sshCG values determined and NT measured at a gestational age of 11 to 14 weeks, as determined from crown rump length (CRL). The distribution of gestational age-independent multiples of the median (MoM) of the parameters was defined and reference intervals established. Three methods for determination of PAPP-A, one manual in-house poly-monoclonal ELISA and two commercial semi-automatic double-monoclonal methods, i.e. PAPP-A for the AutoDelfia platform and PAPP-A for the Kryptor platform, were compared in 260 women. RESULTS All markers had log-normally distributed MoMs. Gestational age independent reference intervals were established. Maternal weight should be included in risk algorithms. The semi-automated PAPP-A assays (AutoDelfia and Kryptor) gave similar values, mean difference 10.5 %, whereas the manual assay gave higher values, mean differences 50.4 % and 41.0 %, respectively, CONCLUSIONS This calls for better standardization and a uniform quality control scheme that is focused on discriminatory ability rather than adherence to mean values from a large number of laboratories.
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Affiliation(s)
- K R Wøjdemann
- Copenhagen University Hospital, Department of Obstetrics and Gynaecology, Hvidovre Hospital, Denmark
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Christiansen M, Jaliashvili I. Total pregnancy‐associated plasma protein A—a first trimester maternal serum marker for Down's syndrome: clinical and technical assessment of a poly‐monoclonal enzyme immunoassay. Scandinavian Journal of Clinical and Laboratory Investigation 2009; 63:407-15. [PMID: 14594321 DOI: 10.1080/00365510310002248] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Pregnancy-associated plasma protein A (PAPP-A) is a maternal serum marker of fetal chromosomal disease and a risk marker for adverse outcome. PAPP-A in the circulation exists both as a 2:2 complex (PAPP-A/proMBP) with the proform of eosinophil major basic protein (proMBP) and as dimeric PAPP-A. Non-PAPP-A containing proMBP complexes constitute the bulk of proMBP in maternal serum. We developed and characterized a sandwich enzyme immunoassay for PAPP-A using a polyclonal rabbit anti-PAPP-A/proMBP antibody (SSI 6823) and a monoclonal murine anti-PAPP-A/proMBP antibody (HYB 234-3), reactive with the PAPP-A part of PAPP-A/proMBP. The assay range was 2 mIU/L-500 mIU/L, intra- and inter-assay coefficients of variation <10%. The immunoreactivity eluted ahead of thyroglobulin, Mr 669 kDa, in gel filtration and bound to a heparin column. Serum concentrations of PAPP-A were determined in gestational weeks 5-13 in 167 pregnant women with normal fetuses and 39 women with Down's syndrome (DS) fetuses. The median PAPP-A MoM (multiples of the median in normal controls) in DS pregnancies was 0.30 (quartile range: 0.17-0.54). The PAPP-A logMoMs in DS pregnancies were normally distributed with a mean of -0.5927 and SD of 0.3639. When simulating the performance of PAPP-A and age as markers for DS in population screening a detection rate (DR) of 62% was found for a screen positive rate (SPR) of 5%. Together with beta-HCG and nuchal translucency, two other first trimester markers for fetal DS, a DR 90% could be obtained for an SPR of 5%.
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Affiliation(s)
- M Christiansen
- Department of Clinical Biochemistry, Statens Serum Institut, Copenhagen, Denmark.
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Laigaard J, Larsen SO, Pedersen NG, Hedley PL, Gjerris AC, Wøjdemann KR, Shalmi AC, Sundberg K, Tabor A, Christiansen M. ADAM 12-S in first trimester: fetal gender, smoking and maternal age influence the maternal serum concentration. Prenat Diagn 2009; 29:525-7. [PMID: 19266494 DOI: 10.1002/pd.2075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Hedley P, Christiansen M. Serum leptin in first-trimester Down syndrome pregnancies. Prenat Diagn 2008; 28:475-7. [DOI: 10.1002/pd.1998] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ardawi MSM, Nasrat HA, Rouzi AA, Qari MH, Al-Qahtani MH, Abuzenadah AM. Maternal serum free-beta-chorionic gonadotrophin, pregnancy-associated plasma protein-A and fetal nuchal translucency thickness at 10-13(+6) weeks in relation to co-variables in pregnant Saudi women. Prenat Diagn 2007; 27:303-11. [PMID: 17269128 DOI: 10.1002/pd.1661] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
OBJECTIVE To establish normative values and distribution parameters of first-trimester screening markers, namely, fetal nuchal translucency (NT), maternal serum free beta-human chorionic gonadotrophin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A), at 10 to 13(+6) weeks of gestation in Saudi women and to evaluate the effect of co-variables including maternal body weight, gravidity, parity, fetal gender, twin pregnancy, smoking and ethnicity on these markers. METHODS A cohort of Saudi women (first cohort n = 1616) with singleton pregnancies prospectively participated in the present study, and fetal NT together with maternal serum free beta-hCG and PAPP-A were determined at 10 to 13(+6) weeks of gestation. The distribution of gestational age-independent multiples of the median (MoM) of the parameters was defined and normative values were established, and correction for maternal body weight was made accordingly. The influence of various co-variables was examined using the data collected from the first and the second (n = 1849) cohorts of women and 62 twin pregnancies, and compared with other studies. RESULTS All markers exhibited log-normally distributed MoMs. Gestational age-independent normative values were established. Maternal body weight was corrected, particularly for maternal free beta-hCG and PAPP-A using standard methods. Fetal NT showed a negative relationship with increasing gravidity (r = -0.296) or parity (r = -0.311), whereas both free beta-hCG and PAPP-A exhibited a significant positive relationship. There was a significant increase in the MoM of free beta-hCG in female fetuses. Smoking decreased MoM values of free beta-hCG (by 14.6%; P < 0.01) and PAPP-A (by 18.8%; P < 0.001). Twin pregnancy showed significant increases in MoM values of free beta-hCG (by 1.87-fold) and PAPP-A (by 2.24-fold), with no significant changes in fetal NT MoM values. Fetal NT MoM values were lower in Africans and Asians but higher in Orientals, as compared to Saudi women (P < 0.05; in each case). MoM values (body weight-corrected) of free beta-hCG were 25.2% higher in Africans and 19.4% higher in Orientals but 6.8% lower in other Arabian and Asian (by 5.8%) women as compared to Saudi women (P < 0.05; in each case). CONCLUSIONS The normative values and distribution parameters for fetal NT, maternal serum free beta-hCG and PAPP-A were established in Saudi singleton pregnancies, the maternal body weight together with smoking, twin pregnancy and ethnicity being important first-trimester screening co-variables. Gravidity, parity and fetal gender are also considered to influence one or more of the first-trimester markers examined.
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Affiliation(s)
- Mohammed-Salleh M Ardawi
- Department of Clinical Biochemistry, Faculty of Medicine and King Abdulaziz University Hospital, King Abdulaziz University, Jeddah, Saudi Arabia.
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Christiansen M, Høgdall EV, Larsen SO, Høgdall C. The variation of risk estimates through pregnancy in second trimester maternal serum screening for Down syndrome. Prenat Diagn 2002; 22:385-7. [PMID: 12001192 DOI: 10.1002/pd.297] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The variation of risk estimates in second trimester maternal serum screening for Down's syndrome has been shown to be considerable in quality control schemes, i.e. UKNEQAS. We studied the biological variation of risk estimates in 16 women through pregnancy. The maternal serum markers alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), unconjugated estriol (uE3) and beta-hCG were determined six times during late first to late second trimester, and the associated likelihood ratios for Down syndrome were calculated. The interpersonal variation of markers, as well as that of the likelihood ratio, was much greater than the intrapersonal variation. The average intrapersonal standard deviation (SD) of the triple test log likelihood ratio was 0.2291, corresponding to a central 95-percentile interval 0.36-2.81 of the likelihood ratio. The interpersonal SD of the log likelihood ratio was 0.5482, corresponding to a central 95-percentile interval 0.08-11.87 of the likelihood ratio. The large difference between the intra- and interpersonal variation makes it unlikely that biological variation through pregnancy is a major contributor to the variation of risk estimates obtained several times in the same pregnancy. Rather, improvements in analytical quality and laboratory management must be expected to result in reduced variation and, in consequence, better performance of screening.
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Affiliation(s)
- Michael Christiansen
- Department of Clinical Biochemistry, Statens Serum Institut, Copenhagen, Denmark.
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Current Awareness. Prenat Diagn 2002. [DOI: 10.1002/pd.266] [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]
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Qin QP, Christiansen M, Pettersson K. Point-of-Care Time-resolved Immunofluorometric Assay for Human Pregnancy-associated Plasma Protein A: Use in First-Trimester Screening for Down Syndrome. Clin Chem 2002. [DOI: 10.1093/clinchem/48.3.473] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractBackground: Screening for Down syndrome in the first trimester by a combination of fetal nuchal translucency thickness and maternal serum pregnancy-associated plasma protein A (PAPP-A) and free β-human chorionic gonadotropin has been shown to be effective and efficient. We aimed to develop a fast point-of-care assay that could be placed in one-stop clinics for the measurement of PAPP-A.Methods: We developed a two-site, one-step assay that uses two monoclonal antibodies (mAbs) to PAPP-A, based on a dry-reagent, all-in-one immunoassay concept with a stable fluorescent lanthanide chelate and time-resolved fluorometry. One antibody (mAb 10E1) was biotinylated, and the other (mAb 234-5) was europium-labeled, both via the ε-amino groups of surface lysine residues. The assay was performed on an AIO immunoanalyzer at 36 °C in single, streptavidin-coated microtitration wells that contained the dry reagents. PAPP-A, either in free or complexed form, was detected by the antibodies used.Results: The assay procedure required 20 min and used 10 μL of sample. The calibration curve was linear from 5 to 10 000 mIU/L. The detection limit was 0.5 mIU/L. Intra- and interassay imprecision (CV) was ≤4.3% and 8.3%, respectively, for whole blood, plasma, or serum samples. Recovery was 93–96% for serum, 95–108% for heparin-derived whole blood, and 98–103% for heparin-derived plasma. Parallelism was observed in all three matrices. Results correlated [slope = 0.85 (confidence interval, 0.82–0.87); intercept = −33 (confidence interval, −58 to −9); Sy|x = 85 mIU/L; r = 0.991; n = 100] with those obtained by a Delfia assay. Heparin did not affect the assay, but EDTA markedly reduced PAPP-A values. PAPP-A was stable at 4 °C for at least 18 days in serum and for 8 days in heparin-derived whole blood or plasma.Conclusions: The present assay appears suited for use in one-stop clinics for screening for Down syndrome in the first trimester, with results available within 1 h.
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Affiliation(s)
- Qiu-Ping Qin
- Department of Biotechnology, University of Turku, Tykistökatu 6, 20520 Turku, Finland
| | - Michael Christiansen
- Department of Clinical Biochemistry, Statens Seruminstitut, Artillerivej 5, DK-2300 S Copenhagen, Denmark
| | - Kim Pettersson
- Department of Biotechnology, University of Turku, Tykistökatu 6, 20520 Turku, Finland
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Wøjdemann KR, Christiansen M, Sundberg K, Larsen SO, Shalmi A, Tabor A. Quality assessment in prospective nuchal translucency screening for Down syndrome. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2001; 18:641-644. [PMID: 11844206 DOI: 10.1046/j.0960-7692.2001.00592.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
OBJECTIVES To develop and apply a quality control system in a Down syndrome screening study using nuchal translucency as an interventional marker. METHODS In a prospective Down syndrome screening study fetal nuchal translucency thickness was measured in 9236 of the 10 045 examined pregnancies. For quality assessment two models were introduced: firstly, image-scoring evaluation of the nuchal translucency thickness measurements and secondly, establishment of the distributions of nuchal translucency multiples of the median over time and the influence of intervention. RESULTS The observer variability in the image-scoring evaluation was high with a kappa value of 0.48 in the overall validation. A revised model showed better interobserver agreement with a kappa value of 0.58; however, comparing the individual criteria the differences were still unsatisfactory, i.e. we found highly significant differences in the criteria "position of the fetus" (P = 0.0026) and "magnification of the image" (P = 0.0001). Regarding the distributions of the nuchal translucency multiples of the median, the median stabilized after a short learning phase representing the practical part of the sonographer's certification to nuchal translucency screening. In groups of medians of 50 nuchal translucency multiples of the median the intergroup standard deviation decreased from 0.100-0.060 after the learning phase to 0.046 after intervention. CONCLUSIONS When well-trained certified examiners perform nuchal translucency screening, continuous evaluation of the distribution of the nuchal translucency multiples of the median seems to be a good method to assess the quality for a center and may also be used to identify individual examiners deviating from the mean performance. The image-scoring methods we introduced cannot be recommended for quality control in a nuchal translucency screening program.
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Affiliation(s)
- K R Wøjdemann
- Copenhagen University Hospital, Department of Obstetrics and Gynaecology, Hvidovre Hospital, Kettegaard Allé 30, DK-2650 Hvidovre, Denmark.
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