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External Validation Study of First Trimester Obstetric Prediction Models (Expect Study I): Research Protocol and Population Characteristics.

ABSTRACT: BACKGROUND:A number of first-trimester prediction models addressing important obstetric outcomes have been published. However, most models have not been externally validated. External validation is essential before implementing a prediction model in clinical practice. OBJECTIVE:The objective of this paper is to describe the design of a study to externally validate existing first trimester obstetric prediction models, based upon maternal characteristics and standard measurements (eg, blood pressure), for the risk of pre-eclampsia (PE), gestational diabetes mellitus (GDM), spontaneous preterm birth (PTB), small-for-gestational-age (SGA) infants, and large-for-gestational-age (LGA) infants among Dutch pregnant women (Expect Study I). The results of a pilot study on the feasibility and acceptability of the recruitment process and the comprehensibility of the Pregnancy Questionnaire 1 are also reported. METHODS:A multicenter prospective cohort study was performed in The Netherlands between July 1, 2013 and December 31, 2015. First trimester obstetric prediction models were systematically selected from the literature. Predictor variables were measured by the Web-based Pregnancy Questionnaire 1 and pregnancy outcomes were established using the Postpartum Questionnaire 1 and medical records. Information about maternal health-related quality of life, costs, and satisfaction with Dutch obstetric care was collected from a subsample of women. A pilot study was carried out before the official start of inclusion. External validity of the models will be evaluated by assessing discrimination and calibration. RESULTS:Based on the pilot study, minor improvements were made to the recruitment process and online Pregnancy Questionnaire 1. The validation cohort consists of 2614 women. Data analysis of the external validation study is in progress. CONCLUSIONS:This study will offer insight into the generalizability of existing, non-invasive first trimester prediction models for various obstetric outcomes in a Dutch obstetric population. An impact study for the evaluation of the best obstetric prediction models in the Dutch setting with respect to their effect on clinical outcomes, costs, and quality of life-Expect Study II-is being planned. TRIAL REGISTRATION:Netherlands Trial Registry (NTR): NTR4143; http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=4143 (Archived by WebCite at http://www.webcitation.org/6t8ijtpd9).

SUBMITTER: Meertens LJE

PROVIDER: S-EPMC5680517 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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External Validation Study of First Trimester Obstetric Prediction Models (Expect Study I): Research Protocol and Population Characteristics.

Meertens Linda Jacqueline Elisabeth LJE Scheepers Hubertina Cj HC De Vries Raymond G RG Dirksen Carmen D CD Korstjens Irene I Mulder Antonius Lm AL Nieuwenhuijze Marianne J MJ Nijhuis Jan G JG Spaanderman Marc Ea ME Smits Luc Jm LJ

JMIR research protocols 20171026 10

<h4>Background</h4>A number of first-trimester prediction models addressing important obstetric outcomes have been published. However, most models have not been externally validated. External validation is essential before implementing a prediction model in clinical practice.<h4>Objective</h4>The objective of this paper is to describe the design of a study to externally validate existing first trimester obstetric prediction models, based upon maternal characteristics and standard measurements (e ...[more]

PMID: 29074472

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Project description:BackgroundPregnancy loss prediction based on routinely measured ultrasound characteristics is generally aimed toward distinguishing nonviability. Physicians also use ultrasound indicators for patient counseling, and in some cases to decide upon the frequency of follow-up sonograms. To improve clinical utility, allocation of cut-points should be based on clinical data for multiple sonographic characteristics, be specific to gestational week, and be determined by methods that optimize prediction.ObjectivesTo identify routinely measured features of the early first trimester ultrasound and the gestational age-specific cut-points that are most predictive of pregnancy loss.Materials and methodsThis was a secondary analysis of 617 pregnant women enrolled in the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial; all women had 1-2 previous pregnancy losses and no documented infertility. Each participant had a single ultrasound with a detectable fetal heartbeat between 6 weeks 0 days and 8 weeks 6 days. Cut-points for low fetal heart rate and small crown-rump length were separately defined for gestational weeks 6, 7, and 8 to optimize prediction. Identity and log-binomial regression models were used to estimate absolute and relative risks, respectively, and 95% confidence intervals between jointly categorized low fetal heart rate, small crown-rump length, and clinical pregnancy loss. Adjusted models accounted for gestational age at ultrasound in weeks. Missing data were addressed using multiple imputation.ResultsA total of 64 women experienced a clinical pregnancy loss following the first ultrasound (10.4%), 7 were lost to follow-up (1.1%), and 546 women (88.5%) had a live birth. Low fetal heart rate and small crown-rump length (≤122, 123, and 158 bpm; ≤6.0, 8.5, and 10.9 mm for gestational weeks 6, 7, and 8, respectively) were independent predictors of clinical pregnancy loss, with greatest risks observed for pregnancies having both characteristics (relative risk, 2.08; 95% confidence interval, 1.24-2.91). The combination of low fetal heart rate and small crown-rump length was linked to a 16% (95% confidence interval, 9.1-23%) adjusted absolute increase in risk of subsequent loss, from 5.0% (95% confidence interval, 1.5-8.5%) to 21% (95% confidence interval, 15-27%). Abnormal yolk sac diameter or the presence of a subchorionic hemmhorage did not improve prediction of clinical pregnancy loss.ConclusionIdentified cut-points can be used by physicians for patient counseling, and in some cases to decide upon the frequency of follow-up sonograms. The specified criteria should not be used to diagnose nonviability.

Project description:ObjectivesAn obstetric comorbidity index has been developed recently with superior performance characteristics relative to general comorbidity measures in an obstetric population. This study aimed to externally validate this index and to examine the impact of including hospitalisation/delivery records only when estimating comorbidity prevalence and discriminative performance of the obstetric comorbidity index.DesignValidation study.SettingAlberta, Canada.PopulationPregnant women who delivered a live or stillborn infant in hospital (n = 5995).MethodsAdministrative databases were linked to create a population-based cohort. Comorbid conditions were identified from diagnoses for the delivery hospitalisation, all hospitalisations and all healthcare contacts (i.e. hospitalisations, emergency room visits and physician visits) that occurred during pregnancy and 3 months pre-conception. Logistic regression was used to test the discriminative performance of the comorbidity index.Main outcome measuresMaternal end-organ damage and extended length of stay for delivery.ResultsAlthough prevalence estimates for comorbid conditions were consistently lower in delivery records and hospitalisation data than in data for all healthcare contacts, the discriminative performance of the comorbidity index was constant for maternal end-organ damage [all healthcare contacts area under the receiver operating characteristic curve (AUC) = 0.70; hospitalisation data AUC = 0.67; delivery data AUC = 0.65] and extended length of stay for delivery (all healthcare contacts AUC = 0.60; hospitalisation data AUC = 0.58; delivery data AUC = 0.58).ConclusionsThe obstetric comorbidity index shows similar performance characteristics in an external population and is a valid measure of comorbidity in an obstetric population. Furthermore, the discriminative performance of the comorbidity index was similar for comorbidities ascertained at the time of delivery, in hospitalisation data or through all healthcare contacts.

Project description:The brush-border glycoproteins of first-trimester human placentas were investigated by using two external labelling techniques: (1) sequential digestion with neuraminidase and galactose oxidase, followed by reduction with NaB3H4, which 3H-labels terminal galactose and galactosamine residues; and (2) sequential treatment with periodate and NaB3H4, which 3H-labels terminal sialic acid residues. The labelling procedures were performed on intact tissue so that the results would more closely approximate the topography of the brush border in vivo. The microvilli were isolated, subjected to sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, and the [3H]glycoproteins detected by fluorography. Densitometer scans of the fluorograms of the [3H]galactoproteins showed that, under reducing conditions, 90% of the protein-associated radioactivity was incorporated into two glycoproteins. The major [3H]galactoprotein of early placental microvilli had an estimated molecular mass of 92 kDa (desialylated) and migrated as a diffuse band. A minor 180 kDa glycoprotein was less consistently labelled. No change in the apparent molecular mass of either component was detected in the absence of beta-mercaptoethanol, suggesting that the 180 kDa component was not a dimer of the 92 kDa glycoprotein. The remaining 10% the radioactivity was equally distributed among several minor membrane components. Densitometer scans of the fluorograms of the [3H]sialoproteins showed that, under either reducing or non-reducing conditions, 90% of the 3H was preferentially incorporated into the 92-110 kDa region of the gel. Although no distinct bands were visible, the higher-molecular-mass region of this area was always most heavily labelled. A minor 180 kDa glycoprotein was also 3H-labelled. The pattern of brushborder [3H]glycoproteins from first-trimester placentas differed markedly from that of term placental microvilli and from placental fibroblast plasma membranes that were 3H-labelled by identical external labelling techniques. These results indicate that: (1) the glycoprotein determinants of brush-border topography change during pregnancy; (2) within the placenta, the major 92 kDa (desialylated) determinant, which has not been previously described, is unique to the trophoblastic cells.

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External Validation Study of First Trimester Obstetric Prediction Models (Expect Study I): Research Protocol and Population Characteristics.

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External Validation Study of First Trimester Obstetric Prediction Models (Expect Study I): Research Protocol and Population Characteristics.

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