Cost-effectiveness analysis of a model of first-trimester prediction and prevention of preterm pre-eclampsia compared with usual care

Cost-effectiveness of a randomized controlled trial comparing low-dose aspirin to placebo for the prevention of recurrent preterm birth

To assess the cost-effectiveness of low-dose aspirin compared to placebo for the prevention of recurrent preterm birth from a healthcare perspective. This was a cost-effectiveness analysis alongside a multicenter, randomized, double-blinded, placebo-controlled trial. We included women with a singleton pregnancy and a previous spontaneous preterm birth <37 weeks of gestation of a singleton. Women were randomized between aspirin 80 mg daily and placebo, initiated between 8 and 16 weeks of gestation. We estimated the difference in preterm births (<37 weeks of gestation), and maternal and neonatal healthcare costs using seemingly unrelated linear regression analyses. Bootstrapping was performed to estimate statistical uncertainty. A total of 387 women were included: 194 in the aspirin group and 193 in the placebo group. We observed a small, statistically non-significant difference in preterm birth (21.2% vs. 25.4%; risk difference -4.3%; 95% CI: -12.7% to 4.1%) and healthcare costs (mean -€99; 95% CI: -€2385 to €2325) in the aspirin group compared to placebo. The cost-effectiveness acceptability curve showed that the probability of aspirin being cost-effective was 54% for a willingness to pay threshold of €0 for one prevented preterm birth and 78% for €50 000 for one prevented preterm birth. Our findings suggest that aspirin is the dominant strategy over placebo for the prevention of preterm birth. However, there was substantial uncertainty around the results and definite conclusions regarding the cost-effectiveness of aspirin cannot be drawn.

Neonatal cost savings in hypertensive disorders of pregnancy: Economic evaluation of the sFlt-1/PlGF test with real world implementation of biomarkers

BACKGROUND

Preeclampsia is a key cause of prematurity in the U.S. and incurs significant healthcare costs. An imbalance between soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) predicts severe preeclampsia and aids in its management.

OBJECTIVE

This study aimed to assess the cost-effectiveness of the sFlt-1/PlGF test as an addition to standard care for patients at risk of developing preeclampsia.

STUDY DESIGN

A decision tree analysis was conducted to assess the cost effectiveness of the ratio test in the United States, using data from Preeclampsia Risk Assessment: Evaluation of Cut-offs to Improve Stratification [PRAECIS] and from a real-world evidence study conducted after the implementation of sFlt-1/PlGF testing into routine clinical practice (Biomarker Examination and Analysis for Clinical Obstetrical Navigation Study [BEACON]). The model compared standard of care alone versus a biomarker-based approach utilizing the sFlt-1/PlGF test for managing patients at risk of preeclampsia with severe features. Published data was used to estimate theoretical cost values of infants for their first six months of life.

RESULTS

The analysis indicated potential total neonatal cost savings of nearly $10,595,332 (95% CI: $6,555,439 to $14,730,536) per 1,000 patients using the sFlt-1/PlGF ratio test, translating to about $10,595 saved per patient. The incremental cost-effectiveness ratio (ICER) analysis showed a mean cost savings of $62,572 for each pregnancy prolonged by two weeks.

CONCLUSION

The sFlt-1/PlGF test, when used alongside standard care, enhances risk stratification for severe preeclampsia and may lead to significant neonatal cost savings by reducing preterm deliveries and neonatal intensive care admissions.

The impact of aspirin combined with labetalol on coagulation function and pregnancy outcomes in pre-eclamptic pregnant women

BACKGROUND

This study aimed to analyze the impact of aspirin combined with labetalol on coagulation function and pregnancy outcomes in women with pre-eclampsia.

METHODS

A total of 98 pregnant women with pre-eclampsia admitted to our hospital from September 2019 to March 2021 were selected for the retrospective analysis. Patient records were reviewed and divided into a control group (n = 49) who received labetalol and an observation group (n = 49) who received aspirin combined with labetalol. Extracted from the case collection system and observed: clinical efficacy, occurrence of adverse pregnancy outcomes, and adverse reactions.

RESULTS

The total effective rate in the observation group was higher than that in the control group. After treatment, the observation group had lower systolic blood pressure, diastolic blood pressure, D-D, Scr, β2-MG, and MA levels compared to the control group, and higher TT, PT and APTT levels. The occurrence rate of adverse pregnancy outcomes such as preterm delivery, intrauterine distress, postpartum hemorrhage, and fetal heart abnormalities was lower in the observation group than in the control group. There were no statistically significant differences in adverse reactions such as nausea, vomiting, hypotension, ocular tremor, and facial flushing between the two groups.

CONCLUSION

Aspirin combined with labetalol has ideal therapeutic efficacy in women with pre-eclampsia. It can enhance the antihypertensive effect, improve the coagulation status of the body, protect renal function, improve adverse pregnancy outcomes, and is considered safe and reliable, deserving adoption.

Combined first-trimester screening for preterm small-for-gestational-age infants: Australian multicenter clinical feasibility study

OBJECTIVE

To assess the performance of the Fetal Medicine Foundation (FMF) first-trimester competing-risks screening model for small-for-gestational-age (SGA) fetuses requiring delivery at < 37 weeks' gestation, in a large cohort of women receiving maternity care in Australia.

METHODS

This was a retrospective analysis of prospectively collected data from a cohort of women attending one of two private multicenter fetal medicine practices for first-trimester screening for preterm pre-eclampsia (PE), defined as PE requiring delivery before 37 weeks' gestation. Risk for preterm SGA, defined as SGA requiring delivery before 37 weeks, was calculated but was not disclosed to the patient or referring physician. Screening data were matched to obstetric outcomes. The primary outcome was the efficacy of the FMF screening model in assessing the risk of preterm SGA. The potential effect on identifying other adverse pregnancy outcomes was also assessed.

RESULTS

During the study period, 22 841 women with a singleton pregnancy underwent combined first-trimester screening for preterm PE. These data were compared with those of 301 721 women in the state of Victoria with a singleton pregnancy who did not undergo screening during the study period. Calculation of the risk for preterm SGA identified 3030 (13.3%) pregnancies as high risk. The sensitivity of the model was 48.6% (95% CI, 41.0-56.2%), specificity was 87.0% (95% CI, 86.6-87.5%) and positive and negative predictive values were 2.9% (95% CI, 2.7-3.1%) and 99.5% (95% CI, 99.4-99.6%), respectively. Pregnancies at high risk for preterm SGA were also more likely to have preterm PE (risk ratio (RR), 2.28 (95% CI, 1.72-3.03)) and preterm birth (RR, 1.46 (95% CI, 1.32-1.63)), compared with unscreened pregnancies. Pregnancies at low risk for preterm SGA were less likely to result in a stillbirth (RR, 0.64 (95% CI, 0.47-0.86)) compared with unscreened pregnancies.

CONCLUSION

Combined first-trimester screening for preterm SGA shows moderate screening efficacy and therefore could help to inform pregnancy management and improve antenatal resource allocation. © 2025 International Society of Ultrasound in Obstetrics and Gynecology.

Redesigning antenatal care: Prospective use of an implementation framework to establish a population-based multidisciplinary first-trimester screening, assessment and prevention service

BACKGROUND

Australian rates of adverse obstetric outcomes have improved little despite guidelines recommending history-based screening and intervention. The first trimester provides a unique opportunity to predict and prevent complications, yet population-based screening has failed to be translated into broad clinical practice.

AIMS

This study aimed to redesign antenatal care within an Australian public healthcare centre to align with evidence-based maternity care, including population-based first-trimester screening with early initiation of preventative strategies in high-risk pregnancies.

METHODS

A five-phase action-process model, sharing key elements with implementation science theory, was used to explore barriers to change in antenatal care, co-design a novel service with consumers and establish a population-based antenatal pathway commencing with a multidisciplinary first-trimester screening, assessment and planning visit.

RESULTS

The case for change and associated barriers were defined from the perspective of antenatal care stakeholders. Key needs of each group were established, and solutions were created using co-design methodology, allowing the team to create a novel approach to antenatal care which directly addressed identified barriers. Implementation of the service was associated with a fall in the median gestation at first specialist maternity care provider visit from 20 to 13 weeks.

CONCLUSIONS

This study confirms the feasibility of establishing a comprehensive first-trimester screening program within a public Australian healthcare setting and highlights a co-design process which places individualised assessment at the forefront of antenatal care. This framework may be applicable to most public maternity settings in Australia, with expansion aimed at providing equity of care, including in rural and remote settings.

Benefits and harms of antenatal and newborn screening programmes in health economic assessments: the VALENTIA systematic review and qualitative investigation

Background

Health economic assessments are used to determine whether the resources needed to generate net benefit from an antenatal or newborn screening programme, driven by multiple benefits and harms, are justifiable. It is not known what benefits and harms have been adopted by economic evaluations assessing these programmes and whether they omit benefits and harms considered important to relevant stakeholders.

Objectives

(1) To identify the benefits and harms adopted by health economic assessments in this area, and to assess how they have been measured and valued; (2) to identify attributes or relevance to stakeholders that ought to be considered in future economic assessments; and (3) to make recommendations about the benefits and harms that should be considered by these studies.

Design

Mixed methods combining systematic review and qualitative work.

Systematic review methods

We searched the published and grey literature from January 2000 to January 2021 using all major electronic databases. Economic evaluations of an antenatal or newborn screening programme in one or more Organisation for Economic Co-operation and Development countries were considered eligible. Reporting quality was assessed using the Consolidated Health Economic Evaluation Reporting Standards checklist. We identified benefits and harms using an integrative descriptive analysis and constructed a thematic framework.

Qualitative methods

We conducted a meta-ethnography of the existing literature on newborn screening experiences, a secondary analysis of existing individual interviews related to antenatal or newborn screening or living with screened-for conditions, and a thematic analysis of primary data collected with stakeholders about their experiences with screening.

Results

The literature searches identified 52,244 articles and reports, and 336 unique studies were included. Thematic framework resulted in seven themes: (1) diagnosis of screened for condition, (2) life-years and health status adjustments, (3) treatment, (4) long-term costs, (5) overdiagnosis, (6) pregnancy loss and (7) spillover effects on family members. Diagnosis of screened-for condition (115, 47.5%), life-years and health status adjustments (90, 37.2%) and treatment (88, 36.4%) accounted for most of the benefits and harms evaluating antenatal screening. The same themes accounted for most of the benefits and harms included in studies assessing newborn screening. Long-term costs, overdiagnosis and spillover effects tended to be ignored. The wide-reaching family implications of screening were considered important to stakeholders. We observed good overlap between the thematic framework and the qualitative evidence.

Limitations

Dual data extraction within the systematic literature review was not feasible due to the large number of studies included. It was difficult to recruit healthcare professionals in the stakeholder's interviews.

Conclusions

There is no consistency in the selection of benefits and harms used in health economic assessments in this area, suggesting that additional methods guidance is needed. Our proposed thematic framework can be used to guide the development of future health economic assessments evaluating antenatal and newborn screening programmes.

Study registration

This study is registered as PROSPERO CRD42020165236.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR127489) and is published in full in Health Technology Assessment; Vol. 28, No. 25. See the NIHR Funding and Awards website for further award information.

Performance of the first-trimester Fetal Medicine Foundation competing risks model for preeclampsia prediction: an external validation study in Brazil

BACKGROUND

The current version of the Fetal Medicine Foundation competing risks model for preeclampsia prediction has not been previously validated in Brazil.

OBJECTIVE

This study aimed (1) to validate the Fetal Medicine Foundation combined algorithm for the prediction of preterm preeclampsia in the Brazilian population and (2) to describe the accuracy and calibration of the Fetal Medicine Foundation algorithm when considering the prophylactic use of aspirin by clinical criteria.

STUDY DESIGN

This was a cohort study, including consecutive singleton pregnancies undergoing preeclampsia screening at 11 to 14 weeks of gestation, examining maternal characteristics, medical history, and biophysical markers between October 2010 and December 2018 in a university hospital in Brazil. Risks were calculated using the 2018 version of the algorithm available on the Fetal Medicine Foundation website, and cases were classified as low or high risk using a cutoff of 1/100 to evaluate predictive performance. Expected and observed cases with preeclampsia according to the Fetal Medicine Foundation-estimated risk range (≥1 in 10; 1 in 11 to 1 in 50; 1 in 51 to 1 in 100; 1 in 101 to 1 in 150; and <1 in 150) were compared. After identifying high-risk pregnant women who used aspirin, the treatment effect of 62% reduction in preterm preeclampsia identified in the Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Preeclampsia Prevention trial was used to evaluate the predictive performance adjusted for the effect of aspirin. The number of potentially unpreventable cases in the group without aspirin use was estimated.

RESULTS

Among 2749 pregnancies, preterm preeclampsia occurred in 84 (3.1%). With a risk cutoff of 1/100, the screen-positive rate was 25.8%. The detection rate was 71.4%, with a false positive rate of 24.4%. The area under the curve was 0.818 (95% confidence interval, 0.773-0.863). In the risk range ≥1/10, there is an agreement between the number of expected cases and the number of observed cases, and in the other ranges, the predicted risk was lower than the observed rates. Accounting for the effect of aspirin resulted in an increase in detection rate and positive predictive values and a slight decrease in the false positive rate. With 27 cases of preterm preeclampsia in the high-risk group without aspirin use, we estimated that 16 of these cases of preterm preeclampsia would have been avoided if this group had received prophylaxis.

CONCLUSION

In a high-prevalence setting, the Fetal Medicine Foundation algorithm can identify women who are more likely to develop preterm preeclampsia. Not accounting for the effect of aspirin underestimates the screening performance.

Externally validated prediction models for pre-eclampsia: systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the performance of existing externally validated prediction models for pre-eclampsia (PE) (specifically, any-onset, early-onset, late-onset and preterm PE).

METHODS

A systematic search was conducted in five databases (MEDLINE, EMBASE, Emcare, CINAHL and Maternity & Infant Care Database) and using Google Scholar/reference search to identify studies based on the Population, Index prediction model, Comparator, Outcome, Timing and Setting (PICOTS) approach until 20 May 2023. We extracted data using the CHARMS checklist and appraised the risk of bias using the PROBAST tool. A meta-analysis of discrimination and calibration performance was conducted when appropriate.

RESULTS

Twenty-three studies reported 52 externally validated prediction models for PE (one preterm, 20 any-onset, 17 early-onset and 14 late-onset PE models). No model had the same set of predictors. Fifteen any-onset PE models were validated externally once, two were validated twice and three were validated three times, while the Fetal Medicine Foundation (FMF) competing-risks model for preterm PE prediction was validated widely in 16 different settings. The most common predictors were maternal characteristics (prepregnancy body mass index, prior PE, family history of PE, chronic medical conditions and ethnicity) and biomarkers (uterine artery pulsatility index and pregnancy-associated plasma protein-A). The FMF model for preterm PE (triple test plus maternal factors) had the best performance, with a pooled area under the receiver-operating-characteristics curve (AUC) of 0.90 (95% prediction interval (PI), 0.76-0.96), and was well calibrated. The other models generally had poor-to-good discrimination performance (median AUC, 0.66 (range, 0.53-0.77)) and were overfitted on external validation. Apart from the FMF model, only two models that were validated multiple times for any-onset PE prediction, which were based on maternal characteristics only, produced reasonable pooled AUCs of 0.71 (95% PI, 0.66-0.76) and 0.73 (95% PI, 0.55-0.86).

CONCLUSIONS

Existing externally validated prediction models for any-, early- and late-onset PE have limited discrimination and calibration performance, and include inconsistent input variables. The triple-test FMF model had outstanding discrimination performance in predicting preterm PE in numerous settings, but the inclusion of specialized biomarkers may limit feasibility and implementation outside of high-resource settings. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

First trimester screening for pre-eclampsia and targeted aspirin prophylaxis: a cost-effectiveness cohort study

OBJECTIVE

Investigate cost-effectiveness of first trimester pre-eclampsia screening using the Fetal Medicine Foundation (FMF) algorithm and targeted aspirin prophylaxis in comparison with standard care.

DESIGN

Retrospective observational study.

SETTING

London tertiary hospital.

POPULATION

5957 pregnancies screened for pre-eclampsia using the National Institute for Health and Care Excellence (NICE) method.

METHODS

Differences in pregnancy outcomes between those who developed pre-eclampsia, term pre-eclampsia and preterm pre-eclampsia were compared by the Kruskal-Wallis and Chi-square tests. The FMF algorithm was applied retrospectively to the cohort. A decision analytic model was used to estimate costs and outcomes for pregnancies screened using NICE and those screened using the FMF algorithm. The decision point probabilities were calculated using the included cohort.

MAIN OUTCOME MEASURES

Incremental healthcare costs and QALY gained per pregnancy screened.

RESULTS

Of 5957 pregnancies, 12.8% and 15.9% were screen-positive for development of pre-eclampsia using the NICE and FMF methods, respectively. Of those who were screen-positive by NICE recommendations, aspirin was not prescribed in 25%. Across the three groups, namely, pregnancies without pre-eclampsia, term pre-eclampsia and preterm pre-eclampsia there was a statistically significant trend in rates of emergency caesarean (respectively 21%, 43% and 71.4%; P < 0.001), admission to neonatal intensive care unit (NICU) (5.9%, 9.4%, 41%; P < 0.001) and length of stay in NICU. The FMF algorithm was associated with seven fewer cases of preterm pre-eclampsia, cost saving of £9.06 and QALY gain of 0.00006/pregnancy screened.

CONCLUSIONS

Using a conservative approach, application of the FMF algorithm achieved clinical benefit and an economic cost saving.

Glycosylated fibronectin improves first-trimester prediction of pre-eclampsia

OBJECTIVE

To determine whether maternal serum glycosylated fibronectin (GlyFn) level in the first trimester increases the sensitivity of the Fetal Medicine Foundation (FMF) triple test, which incorporates mean arterial pressure, uterine artery pulsatility index and placental growth factor, when screening for pre-eclampsia (PE) in an Asian population.

METHODS

This was a nested case-control study of Chinese women with a singleton pregnancy who were screened for PE at 11-13 weeks' gestation as part of a non-intervention study between December 2016 and June 2018. GlyFn levels were measured retrospectively in archived serum from 1685 pregnancies, including 101 with PE, using an enzyme-linked immunosorbent assay (ELISA), and from 448 pregnancies, including 101 with PE, using a point-of-care (POC) device. Concordance between ELISA and POC tests was assessed using Lin's correlation coefficient and Passing-Bablok and Bland-Altman analyses. GlyFn was transformed into multiples of the median (MoM) to adjust for maternal and pregnancy characteristics. GlyFn MoM was compared between PE and non-PE pregnancies, and the association between GlyFn MoM and gestational age at delivery with PE was assessed. Risk for developing PE was estimated using the FMF competing-risks model. Screening performance for preterm and any-onset PE using different biomarker combinations was quantified by area under the receiver-operating-characteristics curve (AUC) and detection rate (DR) at a 10% fixed false-positive rate (FPR). Differences in AUC between biomarker combinations were compared using the DeLong test.

RESULTS

The concordance correlation coefficient between ELISA and POC measurements was 0.86 (95% CI, 0.83-0.88). Passing-Bablok analysis indicated proportional bias (slope, 1.08 (95% CI, 1.04-1.14)), with POC GlyFn being significantly higher compared with ELISA GlyFn. ELISA GlyFn in non-PE pregnancies was independent of gestational age at screening (P = 0.11), but significantly dependent on maternal age (P < 0.003), weight (P < 0.0002), height (P = 0.001), parity (P < 0.02) and smoking status (P = 0.002). Compared with non-PE pregnancies, median GlyFn MoM using ELISA and POC testing was elevated significantly in those with preterm PE (1.23 vs 1.00; P < 0.0001 and 1.18 vs 1.00; P < 0.0001, respectively) and those with term PE (1.26 vs 1.00; P < 0.0001 and 1.22 vs 1.00; P < 0.0001, respectively). GlyFn MoM was not correlated with gestational age at delivery with PE (P = 0.989). Adding GlyFn to the FMF triple test for preterm PE increased significantly the AUC from 0.859 to 0.896 (P = 0.012) and increased the DR at 10% FPR from 64.9% (95% CI, 48.7-81.1%) to 82.9% (95% CI, 66.4-93.4%). The corresponding DRs at 10% FPR for any-onset PE were 52.5% (95% CI, 42.3-62.5%) and 65.4% (95% CI, 55.2-74.5%), respectively.

CONCLUSIONS

Adding GlyFn to the FMF triple test increased the screening sensitivity for both preterm and any-onset PE in an Asian population. Prospective non-intervention studies are needed to confirm these initial findings. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Pre-eclampsia

Pre-eclampsia is a life-threatening disease of pregnancy unique to humans and a leading cause of maternal and neonatal morbidity and mortality. Women who survive pre-eclampsia have reduced life expectancy, with increased risks of stroke, cardiovascular disease and diabetes, while babies from a pre-eclamptic pregnancy have increased risks of preterm birth, perinatal death and neurodevelopmental disability and cardiovascular and metabolic disease later in life. Pre-eclampsia is a complex multisystem disease, diagnosed by sudden-onset hypertension (>20 weeks of gestation) and at least one other associated complication, including proteinuria, maternal organ dysfunction or uteroplacental dysfunction. Pre-eclampsia is found only when a placenta is or was recently present and is classified as preterm (delivery <37 weeks of gestation), term (delivery ≥37 weeks of gestation) and postpartum pre-eclampsia. The maternal syndrome of pre-eclampsia is driven by a dysfunctional placenta, which releases factors into maternal blood causing systemic inflammation and widespread maternal endothelial dysfunction. Available treatments target maternal hypertension and seizures, but the only 'cure' for pre-eclampsia is delivery of the dysfunctional placenta and baby, often prematurely. Despite decades of research, the aetiology of pre-eclampsia, particularly of term and postpartum pre-eclampsia, remains poorly defined. Significant advances have been made in the prediction and prevention of preterm pre-eclampsia, which is predicted in early pregnancy through combined screening and is prevented with daily low-dose aspirin, starting before 16 weeks of gestation. By contrast, the prediction of term and postpartum pre-eclampsia is limited and there are no preventive treatments. Future research must investigate the pathogenesis of pre-eclampsia, in particular of term and postpartum pre-eclampsia, and evaluate new prognostic tests and treatments in adequately powered clinical trials.

The Implementation of Preeclampsia Screening and Prevention (IMPRESS) Study

BACKGROUND

Preeclampsia affects between 2% and 5% of pregnancies and is one of the leading causes of perinatal morbidity and mortality worldwide. Despite strong evidence that the combination of systematic preeclampsia screening based on the Fetal Medicine Foundation preeclampsia risk calculation algorithm with treatment of high-risk patients with low-dose aspirin reduces the incidence of preterm preeclampsia more than currently used risk-factor-based screening, real-world implementation studies have not yet been done in Canada.

OBJECTIVE

This study aimed to assess the operational feasibility of implementing first-trimester screening and prevention of preterm preeclampsia (<37 weeks) alongside a publicly funded first-trimester combined screening program for aneuploidies.

STUDY DESIGN

This was a prospective implementation study. Consecutive pregnant patients referred for first-trimester combined screening (11-13+6 weeks) were offered screening for preeclampsia based on the Fetal Medicine Foundation algorithm concomitantly with their aneuploidy screen. Consenting participants were screened using maternal risk factors, mean arterial pressure, uterine artery Doppler pulsatility index, pregnancy-associated plasma protein-A, and placental growth factor. Risk for preterm preeclampsia (<37 weeks) was calculated using the Fetal Medicine Foundation algorithm, and individuals with a risk score ≥1 per 100 were recommended to use aspirin (162 mg once daily at bedtime, <16-36 weeks). Implementation metrics assessed included: acceptability, operational impact, proportion of aspirin initiation, quality and safety measures, and screen performance.

RESULTS

Between December 1, 2020 and April 23, 2021, 1124 patients consented to preeclampsia screening (98.3% uptake), and 92 (8.2%) screened positive. Appointments for patients receiving first-trimester combined screening aneuploidy and preeclampsia screening averaged 6 minutes longer than first-trimester combined screening alone, and adding uterine artery Doppler pulsatility index averaged 2 minutes. Of the 92 patients who screened as high-risk for preeclampsia, 72 (78.3%) were successfully contacted before 16 weeks' gestation. Of these, 62 (86.1%) initiated aspirin, and 10 (13.9%) did not. Performance audit identified a consistent negative bias with mean arterial pressure measurements (median multiple of the median <1 in 10%); other variables were satisfactory. There were 7 cases of preterm preeclampsia (0.69%): 5 and 2 in the high- and low-risk groups, respectively. Screening detected 5 of 7 (71.4 %) preterm preeclampsia cases, with improved performance after adjustment for aspirin treatment effect.

CONCLUSION

This study confirms the operational feasibility of implementing an evidence-based preeclampsia screening and prevention program in a publicly funded Canadian setting. This will facilitate implementation into clinical service and the scaling up of this program at a regional and provincial level.

Preeclampsia: a report and recommendations of the workshop of the Society for Maternal-Fetal Medicine and the Preeclampsia Foundation

Preeclampsia is a substantial cause of perinatal and maternal morbidity and mortality. The prevalence of this condition has increased over the past several decades. Additional opportunities are needed to foster interdisciplinary collaborations and improve patient care in the setting of preeclampsia. In recognition of the Preeclampsia Foundation's 20th anniversary and its work to advance preeclampsia research and clinical agendas, a 2-day virtual workshop on preeclampsia was cosponsored by the Society for Maternal-Fetal Medicine and the Preeclampsia Foundation and held January 25-26, 2021 in conjunction with the 41st annual pregnancy meeting. Leaders with expertise in preeclampsia research, obstetrical care, primary care medicine, cardiology, endocrinology, global health, and patient advocacy gathered to discuss preeclampsia prediction, prevention, management, and long-term impacts. The goals of the workshop were to review the following issues and create consensus concerning research and clinical recommendations: This report, developed collaboratively between the SMFM and the Preeclampsia Foundation, presents the key findings and consensus-based recommendations from the workshop participants.

Impact of replacing or adding pregnancy-associated plasma protein-A at 11-13 weeks on screening for preterm pre-eclampsia

OBJECTIVE

To assess whether pregnancy-associated plasma protein-A (PAPP-A) alters or provides equivalent screening performance as placental growth factor (PlGF) when screening for preterm pre-eclampsia (PE) at 11-13 weeks of gestation.

METHODS

This was a secondary analysis of a non-intervention screening study of 6546 singleton pregnancies that were screened prospectively for preterm PE in the first trimester between December 2016 and June 2018. Patient-specific risks for preterm PE were estimated by maternal history, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), PlGF and PAPP-A. A competing-risks model with biomarkers expressed as multiples of the median was used. All women and clinicians were blinded to the risk for preterm PE. The performance of screening for preterm PE using PlGF vs PAPP-A vs both PAPP-A and PlGF was assessed by comparing areas under the receiver-operating-characteristics (AUC) curves. McNemar's test was used to compare detection rate at a fixed false-positive rate (FPR) of 10%.

RESULTS

PlGF and PAPP-A were measured in 6546 women, of whom 37 developed preterm PE. The AUC and detection rate at 10% FPR using PlGF in combination with maternal history, MAP and UtA-PI were 0.854 and 59.46%, respectively. The respective values were 0.813 and 51.35% when replacing PlGF with PAPP-A and 0.855 and 59.46% when using both PAPP-A and PlGF. Statistically non-significant differences were noted in AUC when replacing PlGF with PAPP-A (ΔAUC, 0.04; P = 0.095) and when using both PAPP-A and PlGF (ΔAUC, 0.002; P = 0.423). However, on an individual case basis, screening using PlGF in conjunction with maternal history, MAP and UtA-PI identified three (8.1%) additional pregnancies that developed preterm PE and that were not identified when replacing PlGF with PAPP-A. Screening using PAPP-A in addition to maternal history and other biomarkers did not identify any additional pregnancies.

CONCLUSION

On an individual case basis, adoption of a screening strategy that uses PAPP-A instead of PlGF results in reduced detection of preterm PE, consistent with previous literature. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Screening for preeclampsia in twin pregnancies

Twin pregnancies are an important risk factor for preeclampsia, a hypertensive disorder of pregnancy that is associated with a significant risk of maternal and perinatal morbidity. Given the burden of preeclampsia, the identification of women at high risk in early pregnancy is essential to allow for preventive strategies and close monitoring. In singleton pregnancies, the risk factors for preeclampsia are well established, and a combined first-trimester prediction model has been shown to adequately predict preterm disease. Furthermore, intervention with low-dose aspirin at 150 mg/day in those identified as high-risk reduces the rate of preterm preeclampsia by 62%. In contrast, risk factors for preeclampsia in twin pregnancies are less established, the proposed screening models have shown poor performance with high false-positive rates, and the benefit of aspirin for the prevention of preeclampsia is not clearly demonstrated. In this review, we examine the literature assessing prediction and prevention of preeclampsia in twin pregnancies.

When to give aspirin to prevent preeclampsia: application of Bayesian decision theory

BACKGROUND

There is good evidence that first-trimester assessment of the risk for preterm preeclampsia and treatment of the high-risk group with aspirin reduces the incidence of preterm preeclampsia. Furthermore, there is evidence that aspirin is associated with an increased risk of maternal and neonatal hemorrhagic complications. Against this background, there are ongoing debates whether aspirin should be recommended for all women or to a subpopulation of women predicted to be at increased risk of developing preeclampsia. Moreover, if a strategy of the prediction and prevention of preterm preeclampsia is to be used, what method should be used for the prediction, and what risk cutoff should be used to decide on who to treat?

OBJECTIVE

This study aimed to compare the policies of universal treatment, stratified treatment, and no treatment with aspirin.

STUDY DESIGN

Decisions about aspirin prophylaxis were considered from the perspective of the Bayesian decision theory. Using this approach, the treatment policies were evaluated for risks of preterm preeclampsia, effects of aspirin, and trade-offs between the harms and benefits of the treatment. Evidence on the risk of preterm preeclampsia was taken from the Screening programme for pre-eclampsia study, which was a first-trimester screening study for the prediction of preeclampsia. Evidence of the effect of aspirin was taken from the Aspirin for Evidence-Based Preeclampsia Prevention trial, which was a trial of aspirin vs placebo in the prevention of preterm preeclampsia. The trade-off between the benefits and harms of aspirin was specified by addressing the question, "What is the maximum number of women that should be treated to prevent 1 case of preterm preeclampsia?" The number can be considered as an exchange rate between the harms and benefits of using aspirin to prevent preterm PE. Given the uncertainty about the harms associated with aspirin, the treatment policies were compared across a wide range of exchange rates.

RESULTS

For exchange rates between 10 and 1000 women treated with aspirin to prevent 1 case of preterm preeclampsia, the net benefit achieved from the risk assessment and targeted treatment of women at high risk of preterm preeclampsia was higher than that from women with no treatment or women with universal treatment with aspirin.

CONCLUSION

Universal treatment with aspirin should be avoided. Risk-based screening should be used, and the cutoff for taking aspirin should be determined from the consideration of the trade-off between the benefits and harms and detection, false-positive, and screen-positive rates.

Routine first trimester combined screening for preterm preeclampsia in Australia: A multicenter clinical implementation cohort study

OBJECTIVE

To assess pregnancy outcomes following first trimester combined screening for preterm preeclampsia in Australia.

METHODS

We compared pregnancy outcomes of women with singleton pregnancies who underwent first trimester combined preeclampsia screening with the Fetal Medicine Foundation algorithm between 2014 and 2017 in Melbourne and Sydney, Australia, with those from women who received standard care. The primary outcomes were preterm preeclampsia and screening performance. Effect estimates were presented as risk ratios with 95% confidence intervals.

RESULTS

A total of 29 618 women underwent combined screening and 301 566 women received standard care. Women who had combined screening were less likely to have preeclampsia, preterm birth, small neonates, and low Apgar scores than the general population. Women with high-risk results (≥1 in 100) were more likely to develop preterm preeclampsia (2.1% vs. 0.7%, risk ratio [RR] 3.04, 95% CI 2.46-3.77), while low-risk women (risk <1 in 100) had lower rates of preterm preeclampsia (0.2% vs. 0.7%, RR 0.26, 95% CI 0.19-0.35) and other pregnancy complications. Screening detected 65.2% (95% CI 56.4-73.2%) of all preterm preeclampsia cases, with improved performance after adjustment for treatment effect.

CONCLUSIONS

First trimester screening for preeclampsia in clinical practice identified a population at high risk of adverse pregnancy outcomes and low-risk women who may be suitable for less intensive antenatal care.