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Currently, popular methods for prenatal risk assessment of fetal aneuploidies are based on multivariate probabilistic modelling, that are built on decades of scientific research and large-scale multi-center clinical studies. These static models that are deployed to screening labs are rarely updated or adapted to local population characteristics. In this article, we propose an adaptive risk prediction system or ARPS, which considers these changing characteristics and automatically deploys updated risk models. 8 years of real-life Down syndrome screening data was used to firstly develop a distribution shift detection method that captures significant changes in the patient population and secondly a probabilistic risk modelling system that adapts to new data when these changes are detected. Various candidate systems that utilize transfer -and incremental learning that implement different levels of plasticity were tested. Distribution shift detection using a windowed approach provides a computationally less expensive alternative to fitting models at every data block step while not sacrificing performance. This was possible when utilizing transfer learning. Deploying an ARPS to a lab requires careful consideration of the parameters regarding the distribution shift detection and model updating, as they are affected by lab throughput and the incidence of the screened rare disorder. When this is done, ARPS could be also utilized for other population screening problems. We demonstrate with a large real-life dataset that our best performing novel Incremental-Learning-Population-to-Population-Transfer-Learning design can achieve on par prediction performance without human intervention, when compared to a deployed risk screening algorithm that has been manually updated over several years., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

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. Log 10 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 log 10 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.

Objectives: To assess whether adding placental growth factor (PlGF) or replacing pregnancy-associated plasma protein-A (PAPP-A) improves the first trimester combined test performance for trisomy 21., Methods: A total of 11,518 women with a singleton pregnancy who underwent the first trimester combined test between December 2016 and December 2019 were included. PlGF was measured and estimated term risk for trisomy 21 was calculated by (1) adding PlGF to the combined test and (2) replacing PAPP-A with PlGF., Results: Twenty-nine pregnancies had trisomy 21. The combined tests detection rate (DR), false positive rate (FPR) and screen positive rate (SPR) were 89.7%, 5.7% and 6% respectively. DR when adding PlGF to the combined test or replacing PAPP-A remained unchanged. Replacing PAPP-A by PlGF increased FPR and SPR to 6.2% and 6.4% respectively. Adding PlGF to the combined test gave FPR and SPR rates of 5.5% and 5.7% respectively. Change in FPR and SPR was not significant (p > 0.1 for all)., Conclusion: Adding PlGF to the combined test or replacing PAPP-A with PlGF did not improve trisomy 21 DR and resulted in a non-significant marginal change in FPR and SPR., (© 2021 John Wiley & Sons Ltd.)

Objective: The objective of the study was to evaluate the uptake of non-invasive cell-free fetal DNA screening test (NIDT) after a high-risk screening result for trisomy 21 METHODS: Association between maternal and pregnancy characteristics on women's test choice was assessed after adjusting for confounding factors in Hong Kong Chinese women who had a high-risk (term risk ≥1:250) first-trimester or second-trimester screening test at three public hospitals. Main outcome measures were rate of declining further testing and obstetric and maternal factors impacting on patient's selection of testing options., Results: Compared with the pre-NIDT period, the availability of NIDT resulted in a 45% (P < 0.001) reduction in the rate of refusal for further testing and a decrease from 92.2% to 66.7% in the use of invasive diagnostic test after a positive screening test. Nulliparous women with a spontaneous [adjusted odds ratio (aOR) = 2.18, 95% confidence interval (CI) 1.63-2.92] or assisted reproduction pregnancy (aOR = 3.95, 95% CI 1.6-9.32) were more likely to choose NIDT. Women with an adjusted risk of '>1:10' (aOR = 7.36, 95% CI 4.22-12.8) and '1:10 to 1:50' (aOR = 1.53, 95% CI 1.01-2.32) were more likely to opt for chorionic villi sampling or amniocentesis., Conclusions: NIDT reduced the refusal rate. Uptake of NIDT was highest in pregnancies of nulliparous women., (© 2014 John Wiley & Sons, Ltd.)

Objective: To assess the quality of nuchal translucency, (NT) measurements were performed at four public institutions performing routine first trimester combined prenatal screening for Down syndrome., Methods: The median of the NT-MoM distribution and standard deviation (SD) of the log(10) NT-MoM were determined. Sonographers and screening centres distributions were assessed for measures of central tendency (median) and dispersion (log(10) SD). Cumulative Sum (CUSUM) charts were created to assess whether screening centres and individual sonographers who had performed at least 30 NT measurements exhibited any systematic bias by checking whether their CUSUM scores exceeded predefined upper and lower control limits., Results: Of the 36 sonographers, only 67% (n = 24) had performed 30 or more scans. The median NT-MOM at each screening centre ranged from 1.02 to 1.09. Screening centre standard deviations ranged from 0.073 to 0.099. CUSUM charts indicated that only one screening centre remained within the predefined control limits throughout the assessment period. Analysis of variance indicated that a statistically significant difference existed between the log NT-MoM distributions of the individual sonographers (F = 10.7; p <0.0001). Inspection of the individual sonographer CUSUM charts indicated that 11 (45%) of the 24, with more than 30 NT measurements were either under or over measuring the NT., Conclusion: Prospective monitoring and feedback of quality assurance assessment results of sonographers and screening centres should be routinely reported as both are responsible, if equity of screening performance is to be maintained.

Objective: To evaluate the measurement of frontomaxillary facial (FMF) angle at 11 weeks to 13 weeks, 6 days in a Chinese population and its applicability in the screening for fetal trisomy 21., Method: In a retrospective study, the stored images for the measurement of fetal nuchal translucency (NT) thickness in a Chinese population from August 2003 to March 2007 were reviewed for the comparison of the FMF angle between 22 trisomy 21 fetuses (study group) with 220 randomly selected normal fetuses with satisfactory images (control group)., Results: No association between FMF angle and NT, nasal bone length, or fetal heart rate was shown (P > 0.05). But the FMF angle was significantly greater in the trisomy 21 fetuses (89.7 vs 82.8, P < 0.001). The intraobserver and interobserver agreement were assessed in 9.5% (n = 21) normal cases. Mean (SD) differences of two observers were -0.83 (2.69) degrees (P > 0.05). For each observer, mean (SD) differences between the two paired measurements were -0.98 (3.11) degrees and 0.93 (1.80) degrees , respectively (P > 0.05)., Conclusion: Our results indicated that measurement of the FMF angle in the first trimester can be incorporated into the screening of trisomy 21 in the Chinese population, and its application is not affected by intraobserver and interobserver variability.

Objective: To examine the effectiveness of first trimester fetal Trisomy 21 (T21) screening using a combination of maternal age, nuchal translucency, maternal serum levels of free beta-hCG and PAPP-A in a predominantly Chinese population in Hong Kong., Methods: Consecutive women who underwent the combined screening for T21 between 11 and 13 + 6 weeks of gestation between 2003 and 2007 were recruited. Risk of T21 was calculated using Fetal Medicine Foundation algorithm and karyotyping was advised when the risk was 1:300 or above. All women were followed up for pregnancy and fetal outcome., Results: 10,363 fetuses underwent screening. 99% of the women were Chinese and 27.4% were at or above 35 years old. 618 fetuses were screened positive (5.9%), which included 31 cases of T21, 14 cases of T18, 7 cases of T13, 10 cases of 45XO and 7 cases of other chromosomal abnormalities. Among the 9745 screened negative fetuses all but 50 (0.5%) had a known outcome, which included three T21 and four other chromosomal abnormalities. All were subsequently identified at the morphology scan except for one case of T21. The detection rate and false positive rates for T21 were 91.2% and 5.4%, respectively and the positive predictive value for all chromosomal abnormalities was 1 in 9., Conclusions: Combined screening for T21 is highly effective among Chinese women. Training, quality control, regular auditing and follow up are essential to maintain screening standards.

Objective. To assess center and sonographer nuchal translucency (NT) measurements that were performed as part of routine prenatal screening for Down syndrome. Methods. Sonographers were assessed for measures of central tendency and dispersion by comparing them with expected population median and dispersion parameters. NT measurements were converted to multiples of the expected NT values according to CRL (NTMoM) and transformed to their log10 equivalent (log10 NTMoM). Central tendency and measurement were assessed by checking whether the median of the NTMoM distribution and SD of the log10 NTMoM distributions were, respectively, within 5%% or 10%% of the expected median of 1 and SD of 0.1. Assessment was performed using both the Center specific and Fetal Medicine Foundation (FMF) reference NT for Crown rump length (CRL). Results. The median NT MoM was 0.95 MoM using the FMF reference and 1.01 MoM when assessed using our center specific reference median. The difference between the center and FMF derived NT MoMs was statistically significantly ( p < 0.0001). NTMoM medians increased over time at a rate of 0.0099 MoM per year while log10 NT MoM measurement dispersement was similar to the 0.1 value expected and decreased by 0.0048 per year. Conclusion. Centers should routinely monitor the quality of NT measurements used to estimate Down syndrome screening risk and should provide individualized feedback to sonographers of their measures of central tendency and dispersion to ensure consistent and improved performance. NT reference medians adopted from other populations should be assessed and validated against a centers own measurement distribution. [ABSTRACT FROM AUTHOR]