Placental growth factor (PlGF) is a surrogate marker in preeclamptic hypertension

Single-cell RNA-seq reveals developmental deficiencies in both the placentation and the decidualization in women with late-onset preeclampsia

Preeclampsia (PE) is a leading cause of maternal and fetal morbidity and mortality. Although increasing lines of evidence suggest that both the placenta and the decidua likely play roles in the pathogenesis of PE, the molecular mechanism of PE remains elusive partly because of the heterogeneity nature of the maternal-fetal interface. In this study, we perform single-cell RNA-seq on the placenta and the decidual from patients with late-onset PE (LOPE) and women in normal pregnancy. Analyses of single-cell transcriptomes reveal that in LOPE, there are likely a global development deficiency of trophoblasts with impaired invasion of extravillous trophoblasts (EVT) and increased maternal immune rejection and inflammation in the placenta, while there are likely insufficient decidualization of decidual stromal cells (DSC), increased inflammation, and suppressed regulatory functions of decidual immune cells. These findings improve our understanding of the molecular mechanisms of PE.

Evaluation of Maternal Reproductive Outcomes and Biochemical Analysis from Wistar Audiogenic Rats (WAR) and Repercussions in Their Offspring

The objective of the present study was to evaluate maternal reproductive performance, body weight, and frequency of external and internal anomalies of newborns of Wistar Audiogenic Rat (WAR) females as compared with Wistar rats. The adult WAR and Wistar rats were mated within their respective strains. After confirming the pregnancy, the body weights were weekly evaluated. On day 21 of pregnancy, the female rats were anesthetized and sacrificed to evaluate the maternal reproductive outcomes and biochemical profile, newborn weight, and external and internal anomalies. The WAR strain gained less weight during the pregnancy and presented hyperproteinemia, hypertriglyceridemia, and embryonic losses concerning Wistar rats, suggesting an inadequate intrauterine condition for embryonic development and fetal viability. WAR also presented a higher percentage of newborns classified as small for gestational age related to intrauterine growth restriction, which was confirmed by the lower number of ossification centers. There was a higher percentage of skeletal anomalies compared with fetuses of the Wistar dams, confirming their greater susceptibility during the formation and development of their skeletal system. Thus, the WAR presents physiological alterations compromising the viability of their embryos and fetuses, leading to impaired development of the newborns.

Syncytiotrophoblast extracellular microvesicle profiles in maternal circulation for noninvasive diagnosis of preeclampsia

Preeclampsia is the most common placental pathology in pregnant females, with increased morbidity and mortality incurred on the mother and the fetus. There is a need for improved biomarkers for diagnosis and monitoring of this condition. Placental syncytiotrophoblasts at the maternal-fetal interface release nanoparticles, including extracellular microvesicles, into the maternal blood during pregnancy. Syncytiotrophoblast extracellular microvesicles (STEVs) are being studied for their diagnostic potential and for their potential physiologic role in preeclampsia. We hypothesized that STEV profiles in maternal circulation would be altered under conditions of preeclampsia compared to normal pregnancy. Extracellular vesicles (EVs) released by BeWo cells in vitro showed high expression of syncytin-1, but no plac1 expression, demonstrating that trophoblast cell EVs express syncytin-1 on their surface. Placental alkaline phosphatase also showed high expression on BeWo EVs, but due to concern for cross reactivity to highly prevalent isoforms of intestinal and bone alkaline phosphatase, we utilized syncytin-1 as a marker for STEVs. In vivo, syncytin-1 protein expression was confirmed in maternal plasma EVs from Control and Preeclampsia subjects by Western blot, and overall, lower expression was noted in samples from patients with preeclampsia (n = 8). By nanoparticle analysis, EV profiles from Control and Preeclampsia groups showed similar total plasma EV quantities (p = 0.313) and size distribution (p = 0.415), but STEV quantitative signal, marked by syncytin-1 specific EVs, was significantly decreased in the Preeclampsia group (p = 2.8 × 10⁻¹¹). Receiver operating characteristic curve demonstrated that STEV signal threshold cut-off of <0.316 was 95.2% sensitive and 95.6% specific for diagnosis of preeclampsia in this cohort (area under curve = 0.975 ± 0.020). In conclusion, we report that the syncytin-1 expressing EV profiles in maternal plasma might serve as a placental tissue specific biomarker for preeclampsia.

Soluble fms-like tyrosine kinase-1, placental growth factor and their ratio as a predictor for pre-eclampsia in East Asians

OBJECTIVE

To assess the clinical utility of the sFlt-1:PlGF ratio rule-in/rule-out pre-eclampsia either directly or after correcting each marker for gestation and maternal weight.

METHODS

This was a prospective cohort study. sFlt-1, PlGF were measured in 965 women randomized to undergo a single blood withdraw between 20 and 39 weeks of gestation. sFlt-1, PlGF and the sFlt-1:PlGF ratio temporal relationship was determined. sFlt-1 and PlGF were converted to multiples of the expected gestational median (MoM) and adjusted for maternal weight. The 90th centile of the adjusted sFlt-1MoM:PlGFMoM ratio was determined. Clinical utility of the sFlt-1:PlGF ratio (≥38) to rule in/rule-out pre-eclampsia (PE) after 20 weeks of gestation versus that of the sFlt-1MoM:PlGFMoM 90th percentile was assessed in 81 women admitted for management of antenatal hypertension.

RESULTS

The sFlt-1:PlGF ratio had quadratic relationship with gestation whereas the sFlt-1MoM:PlGFMoM ratio log distribution that was Gaussian with a mean of zero and a standard deviation of 0.85 with a 90th percentile equal to 1.08. Thirty-four (42%) of the 81 women admitted for management of their antenatal hypertension had PE, 26 (76.4%) had a sFlt-1:PlGF ratio ≥ 38. Four of the remaining 8 PE affected pregnancies with sFlt-1:PlGF ratio <38 delivered within 7 days, 3 were preterm. Two of the 3 preterm PE pregnancies had sFlt-1MoM:PlGFMoM exceeding 90th percentile.

CONCLUSION

The relative level of the sFlt-1 to PlGF carries prognostic value. A sFlt-1MoM:PlGFMoM ratio exceeding the 90th centile resulted in additional detection of pregnancies which developed PE compared to the conventional sFlt-1:PlGF ratio.

Biochemical markers of placental dysfunction in assisted conception

A possible mechanism for poor perinatal outcomes in singleton pregnancies conceived following assisted reproductive technologies (ART) and those conceived naturally following a period of infertility (>12 months) is thought to be placental dysfunction. This was investigated by measuring plasma concentrations of biochemical markers: (i) soluble fms-like tyrosine kinase1 (sFlt1); (ii) placental growth factor (PlGF); (iii) leptin; and (iv) plasminogen activator inhibitor 2 (PAI-2), serially at four antenatal time points. Baseline concentrations of each marker after delivery were also measured. The control group was naturally conceived singleton pregnancies with no history of infertility. Non-smoking, age-matched nulliparous women with no significant medical history were recruited to all groups. The ART group had significantly lower mean plasma concentrations of PlGF at all antenatal time points compared to the control group (p < 0.001). The subfertility (SF) group had significantly higher mean serum concentrations of leptin than the other groups at all time points (p < 0.001), even after correction for body mass index. There were no significant differences in sFlt1 and PAI-2 concentrations between the groups. Low plasma PlGF concentrations in the ART group might suggest abnormal placentation and/or abnormal function in ART pregnancies with relevance to pathogenesis of pregnancy complications in these women.

Serum VEGF and PGF may be significant markers in prediction of severity of preeclampsia

OBJECTIVE

The aim of this study evaluate the value of vascular endothelial growth factor (VEGF) and placental growth factor (PGF) serum levels in prediction of preeclampsia, severity and onset time of the disease.

METHODS

Twenty five placentas of pregnant women diagnosed with preeclampsia (15 severe preeclampsia, 10 mild preeclampsia) and peripheral venous blood samples were collected. The placental and serum levels of VEGF and PGF were measured.

RESULTS

VEGF level was significantly higher in cases and the optimal cut-off point was calculated as 600.5 to differentiate the cases and the controls, with 64% sensitivity and 100% specificity. There was a significant increase in median serum level of VEGF in severe cases compared to the mild cases and the controls. The optimal cut-off point for VEGF was calculated as 673.5 to differentiate mild and severe cases, with 93.3% sensitivity and 90% specificity. Whereas, PGF was significantly lower in severe cases than that in the mild cases and controls. The optimal cut-off point for PGF was calculated as 16.1 to differentiate mild and severe cases, with 66.7% sensitivity and 100% specificity.

CONCLUSION

VEGF and PGF may be significant markers in prediction of severity of preeclampsia, and VEGF may also be valuable in prediction of preeclampsia.

Presymptomatic prediction of preeclampsia with angiogenic factors, in high risk pregnant women

INTRODUCTION

The aim of this study was to investigate the value of placental growth factor (PLGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and sFlt-1/PLGF ratio, in predicting symptomatic preeclampsia (PE).

METHODS

A prospective longitudinal study was carried out on 71 high risk preeclamptic women cohort. All of them had normal blood pressure level (≤140/90 mmHg) at the time of enrolment, 26.8 ± 1.5 weeks. Maternal blood was collected and plasma was stored in a freezer at -80 °C. PE was defined according to the National High Blood Pressure Education Program Working Group Criteria. Accuracy of angiogenic factors in predicting PE was evaluated using Receiver-operating characteristics.

RESULTS

Maternal plasma concentrations of PLGF and sFlt-1 were able to predict PE (0.90, p < 001; 0.78, p = 0.003, area under the curve, respectively) but the sFlt-1/PLGF ratio presented the best prediction potential over the others (0.95, area under the curve, p < 0.001).

CONCLUSION

All angiogenesis factors were effective biomarkers in predicting PE during the second trimester, before the clinical onset of PE.

Are there financial savings associated with supplementing current diagnostic practice for preeclampsia with a novel test? Learnings from a modeling analysis from a German payer perspective

OBJECTIVE

To quantify the financial impact of adding a novel serum test to the current diagnostic toolkit for preeclampsia (PE) detection in Germany.

METHODS

A decision-analytic model was created to quantify the economic impact of adding a recently developed novel diagnostic test for PE (Roche Diagnostics, Rotkreuz, Switzerland) to current diagnostic practice in Germany. The model simulated a cohort of 1000 pregnant patients receiving obstetric care and quantified the budget impact of adding the novel test to current German PE detection and management practices.

RESULTS

The model estimates that the costs associated with managing a typical pregnancy in Germany are €941 when the novel test is used versus €1579 with standard practice. This represents savings of €637 per pregnant woman, even when the test is used as a supplementary diagnostic tool. The savings are attributed to the novel test's ability to better classify patients relative to current practice, specifically, its ability to reduce false negatives by 67% and false positives by 71%.

CONCLUSION

The novel PE test has the potential to provide substantial cost savings to German healthcare payers, even when used as an addition to standard practice. Better classification of patients at risk for developing PE and declassification of those that are not compared to current practice leads to economic savings for the healthcare system. Furthermore, by reducing the rates of false-positive and false-negative classification relative to current standard of care, the test helps better target healthcare spending and lowers overall costs associated with PE care.

Placental growth factor (PlGF): a key to optimizing fetal growth

The needs of the uterus and the fetus for the provision of nutrients and oxygen, supplied by the blood flow, are understandably extremely high, with the circulatory system playing the most important role in this action. Abnormal vascular growth and transformation that create a high vessel resistance network have been associated with various pregnancy pathologies, including miscarriage, small for gestational age (SGA) fetuses with or without preeclampsia and intrauterine growth restriction (IUGR). Placental growth factor (PlGF) has a major role in vasculogenesis and angiogenesis in human placenta. Low concentrations of PlGF and high concentrations of its inhibitor-soluble Fms-like tyrosine kinase-1 (sFlt-1) are linked with impaired angiogenesis and placental development, leading to the above pregnancy complications. The activity of vascular endothelial growth factor (VEGF), which is the most potent of all angiogenic mediators, is partly modulated by PlGF. Although the mechanisms via which PlGF exerts its various effects are still under investigation, we herein discuss the known actions exerted by this major mediator together with its results on fetal growth.

Expression of angiogenic factors in placenta of stressed rats

The aim of the present study was to analyse the influence of stress on pregnant rats, particularly in terms of maternal, placental and fetal weight, placental morphology and placental gene expression of the angiogenic factors Vegfa and Pgf and their receptors. The parameters were evaluated on gestation Day 20. Maternal, fetal and placental weights were statistically lower in stressed animals than controls, suggesting abnormalities in gestational physiology. Morphologically the placentas of rats subjected to stress were reduced in size and weight, with few glycogen cells and a significant increase in the number of apoptotic cells. Stress caused an increase in placental gene expression of Vegfa (P<0.05) and a reduction in Pgf, Flt1 and Kdr expression (P<0.05). It has been suggested that increased VEGF is associated with vasodilatation and hypotension, but in this model persistent hypertension was present. This study suggests that the limited hypotensive Vegfa response to stress-induced hypertension could result from reduced expression of Flt1/Kdr disrupting specific VEGF pathways. These findings may elucidate one of the multiple possible factors underlying how stress modulates placental physiology, and could aid the understanding of stress-induced gestational disorders.

Examining the correlation between placental and serum placenta growth factor in preeclampsia

OBJECTIVE

Decreased levels of serum placenta growth factor (PlGF) are associated with preeclampsia. We sought to determine whether serum and placental levels of PlGF (sPlGF and pPlGF) are associated with preeclampsia and whether there is a correlation between serum and placental PlGF levels.

STUDY DESIGN

These analyses were part of a larger, prospective, case-control study. Cases were women with preeclampsia. Controls were women without preeclampsia who delivered at term. Analyses included nonparametric tests to compare medians, logistic regression to estimate odds, and calculation of correlation coefficients.

RESULTS

Twenty-four cases (10 preterm, 14 term) were compared with 14 controls. Median levels of PlGF were significantly lower in cases than controls (pPlGF: 232.6 vs 363.4 pg/mL, P = .02; sPlGF: 85.5 vs 274.4 pg/mL, P < .001). Serum and placental PlGF were correlated (overall: 39%, P = .006; cases with preterm preeclampsia and growth restriction: 87%, P = .02).

CONCLUSION

Serum and placental PlGF are independently associated with preeclampsia and correlated with each other.

Late-onset preeclampsia is associated with an imbalance of angiogenic and anti-angiogenic factors in patients with and without placental lesions consistent with maternal underperfusion

OBJECTIVE

An imbalance between maternal angiogenic/anti-angiogenic factors concentrations has been observed in preeclampsia (PE) and other obstetrical syndromes. However, the frequency of pathologic findings in the placenta and the changes in maternal plasma angiogenic/anti-angiogenic factor concentrations differ between late- and early-onset PE. The aim of this study was to determine if the maternal plasma concentrations of placental growth factor (PlGF), soluble endoglin (sEng), and soluble vascular endothelial growth factor receptor-1 and 2 (sVEGFR-1 and sVEGFR-2) are different in late-onset PE with and without placental pathologic findings consistent with maternal underperfusion.

STUDY DESIGN

A cross-sectional study was conducted including 64 uncomplicated women and 66 women with late-onset PE (>34 weeks) who had blood samples and placenta available for pathologic examination. Patients with late-onset PE were divided into those with and without placental histologic findings consistent with maternal underperfusion as proposed by the Society for Pediatric Pathology. Maternal plasma concentrations of PlGF, sEng, sVEGFR-1 and sVEGRF-2 were determined by ELISA. Non-parametric statistics were used for analysis.

RESULTS

1) the prevalence of placental histological findings consistent with maternal underperfusion among women with late-onset PE was higher than that of those with an uncomplicated pregnancy (47% (31/66) vs. 7.8% (5/64), respectively; p < 0.01); 2) patients with late-onset PE and histological findings consistent with maternal underperfusion had a significantly lower median plasma concentration of PlGF, plasma PlGF/sVEGFR-1 ratio and plasma PlGF/sEng ratio than those with late-onset PE without placental underperfusion lesions (each p < 0.05); 3) the most common pathological findings in the placenta of patient with PE were lesions consistent with villous changes (77%, 24/31); and 4) isolated vascular lesions in the placenta were found only in 2 cases (6.5%), and the rest had a combination of villous and vascular lesions.

CONCLUSIONS

Nearly half of the patients with late-onset PE have placental lesions consistent with maternal underperfusion. These lesions are associated with an imbalance in the maternal concentration of angiogenic/anti-angiogenic factors. We propose that there is a link between maternal underperfusion and an anti-angiogenic state characterized by the changes in the concentrations of angiogenic and anti-angiogenic factors in women with late onset PE.

Discovery of the serum biomarker proteins in severe preeclampsia by proteomic analysis

Preeclapsia (PE) is a severe disorder that occurs during pregnancy, leading to maternal and fetal morbidity and mortality. PE affects about 3-8% of all pregnancies. In this study, we conducted liquid chromatography- mass spectrometry/mass spectrometry (LC-MS/MS) to analyze serum samples depleted of the six most abundant proteins from normal and PE-affected pregnancies to profile serum proteins. A total of 237 proteins were confidently identified with <1% false discovery rate from the two groups of duplicate analysis. The expression levels of those identified proteins were compared semiquantitatively by spectral counting. To further validate the candidate proteins with a quantitative mass spectrometric method, selective reaction monitoring (SRM) and enzyme linked immune assay (ELISA) of serum samples collected from pregnant women with severe PE (n = 8) or normal pregnant women (n = 5) was conducted. α2- HS-glycoprotein (AHSG), retinol binding protein 4 (RBP4) and α-1-microglobulin/bikunin (AMBP) and Insulin like growth factor binding protein, acid labile subunit (IGFBP-ALS) were confirmed to be differentially expressed in PE using SRM (P<0.05). Among these proteins, AHSG was verified by ELISA and showed a statistically significant increase in PE samples when compared to controls.

The role of serum markers and uterine artery Doppler in identifying at-risk pregnancies

Measures of placental dysfunction, including maternal serum analytes and Doppler studies, have been linked to adverse pregnancy outcomes, although the predictive ability of any single one is poor. Improved knowledge of the multifactorial nature of many of the adverse outcomes of pregnancy has sparked interest in the use of multi-parameter models that combine maternal serum analytes with measures of placental structure and blood flow. The combination of various first-trimester and second-trimester analytes and uterine artery Doppler screening show promise as potential screening tools, but large prospective studies are needed to further define their role in clinical practice.

Circulating angiogenic and antiangiogenic factors in women with eclampsia

OBJECTIVE

The objective of the study was to determine whether eclampsia has a different circulating profile of angiogenic (placental growth factor [PlGF]) and antiangiogenic factors (soluble vascular endothelial growth factor receptor-1 [sVEGFR-1] and soluble endoglin [sEng]) from severe preeclampsia.

STUDY DESIGN

This cross-sectional study included pregnant women in the following groups: (1) normal pregnancy (n = 40); (2) severe preeclampsia (n = 40); and (3) eclampsia (n = 20). Maternal serum PlGF, sVEGFR-1, and sEng concentrations were determined using an enzyme-linked immunosorbent assay.

RESULTS

The study results included the following: (1) the median concentration of sVEGFR-1 and sEng was higher and of PlGF was lower in severe preeclampsia or eclampsia than in normal pregnancy (P < .001 for all); and (2) the median concentrations of these 3 analytes did not differ significantly between patients with severe preeclampsia and those with eclampsia.

CONCLUSION

Eclampsia is associated with higher maternal circulating concentrations of sVEGFR-1 and sEng and lower concentrations of PlGF than normal pregnancy but with similar concentrations to severe preeclampsia. These findings suggest that eclampsia shares a common pathogenic pathway as severe preeclampsia.

Circulating predictive biomarkers in preeclampsia

The aim of the paper was to review promising prediction biomarkers for preeclampsia. The methods included review of abstracts on PubMed, using "preeclampsia", "biomarker", "prediction" as key words, followed by review of primary papers investigating blood based biomarkers. Angiogenic factors, such as PlGf and sFlt1, and PP13 seem presently to have the best predictive test values for preeclampsia, but sensitivity and specificity is still too low to prove useful in a population screening setting. Biomarker testing should still be part of research protocols. Biomarkers could provide useful in selecting high-risk women for prophylactic trials as well as identifying pregnancies that could profit from closer follow-up.

Serum and plasma determination of angiogenic and anti-angiogenic factors yield different results: the need for standardization in clinical practice

OBJECTIVE

The importance of an anti-angiogenic state as a mechanism of disease in preeclampsia is now recognized. Assays for the determination of concentrations of soluble vascular endothelial growth factor receptor (sVEGFR)-1, sVEGFR-2, placental growth factor (PlGF) and soluble endoglin (sEng) have been developed for research and clinical laboratories. A key question is whether these factors should be measured in plasma or serum. The purpose of this study was to determine if there are differences in the concentrations of these analytes between plasma and serum in normal pregnancy and in preeclampsia.

METHODS

Samples of maternal blood were obtained by venipuncture and collected in EDTA (lavender top) and serum collection tubes (red top). A standard laboratory procedure was implemented for the centrifugation, aliquoting and storage of samples. Plasma and serum from 70 women with normal pregnancies and 34 patients with preeclampsia were assayed for sVEGFR-1, sVEGFR-2, PlGF and sEng by ELISA. Nonparametric paired tests were used for analyses.

RESULTS

A significant difference between plasma and serum concentration was observed for sVEGFR-1 and sVEGFR-2 in normal pregnancy, and for sVEGFR-1, sVEGFR-2, PlGF and sEng in women with preeclampsia.

CONCLUSION

The concentrations of sVEGFR-1, sVEGFR-2, PlGF and sEng when measured in maternal plasma and in serum are different. Therefore, the matrix used for the assay (serum versus plasma) needs to be considered when selecting thresholds for predictive studies and interpreting the growing body of literature on this subject.

First-trimester assessment of placenta function and the prediction of preeclampsia and intrauterine growth restriction

Preeclampsia and intrauterine growth restriction (IUGR) are major contributors to perinatal mortality and morbidity worldwide. Both are characterized by impaired trophoblastic invasion of the maternal spiral arteries and their conversion from narrow muscular vessels to wide non-muscular channels. Despite improvement in the understanding of the pathophysiology of these conditions, ability to accurately identify pregnant woman who will develop them is limited. This greatly impairs the development and testing of preventive interventions. While different measures of placental dysfunction have been associated with increased risk for adverse pregnancy outcomes, the ability of any single one to accurately predict these outcomes is poor. Developing predictive tests is further challenged by difficulty in the timing of the measurements, as both the structural and biochemical characteristics of the placenta change with increasing gestational age. The ideal screening test would accurately predict the development of adverse pregnancy outcomes early enough to provide a window for preventive interventions. Improvement in ultrasound technology provides potentially useful novel tools for evaluating placental structure, but measurements need to be standardized in order to be useful. Maternal serum analyte screening is a noninvasive test of placental biochemical function, but present serum marker alone is not sufficiently accurate to suggest its routine use in clinical practice. The use of first trimester biochemical markers in combination with uterine artery Doppler screening is promising as a potential screening tool. Prospective longitudinal studies using standardized methodology are necessary to further evaluate the choice of parameters and strategies of combination to achieve the best predictive models.

Measurement of sVEGF R1 and PlGF in serum: comparing prototype assays from Beckman Coulter, Inc. to R&D Systems microplate assays

OBJECTIVE

To compare the performance of prototype Access® sVEGF R1 and PlGF automated immunoassays from Beckman Coulter to the Quantikine® microplate ELISA assays by R&D Systems.

METHODS

Samples obtained from pregnant women, non-pregnant women and men were assayed according to manufacturers' instructions.

RESULTS

Compared to the Quantikine assays, the Access assays demonstrated improved precision, increased sensitivity, broader dynamic ranges, and reduced analysis time. The Access assays were found to be specific for free sVEGF R1 and free PlGF.

CONCLUSION

There was good correlation between the Access and Quantikine assays. Superior performance by Access assays may have important prenatal diagnostic implications.

The perinatal implications of angiogenic factors

PURPOSE OF REVIEW

To summarize recent findings relating maternal circulating levels of proteins associated with angiogenesis and the outcome of pregnancy.

RECENT FINDINGS

In preeclampsia, levels of placental growth factor (PlGF) become abnormal prior to soluble fms-like tyrosine kinase 1 (sFlt-1). Longitudinal measurement of changes in protein level are better predictors of disease than measurement at a single time point in pregnancy and also appear to be more strongly associated with early-onset disease. The levels of angiogenic proteins provide additional predictive information over abnormal uteroplacental Doppler. The preeclampsia-like phenotype of rats overexpressing sFlt-1 can be ameliorated by administration of a protein which binds and inactivates sFlt-1. Animal models demonstrate that uteroplacental ischemia leads to elevated maternal serum levels of sFlt-1 and decreased PlGF. Similarly, studies of human trophoblast cells demonstrate that hypoxia stimulates release of sFlt-1. Autocrine vascular endothelial growth factor (VEGF) has a trophic effect on the endothelium, distinct from its control of angiogenesis. By blocking this effect, elevated sFlt-1 could lead to systemic endothelial cell dysfunction, one of the key features of preeclampsia. Low levels of PlGF are associated with intrauterine growth restriction. However, in the first trimester of pregnancy, high levels of sFlt-1 were associated with reduced rates of growth restriction, preterm birth and stillbirth.

SUMMARY

Regulators of the VEGF system may have a causal role in the sequence of events leading to preeclampsia and may be targets for novel therapies. However, better knowledge of the biology is required prior to clinical trials of interventions.

Financial impact of a novel pre-eclampsia diagnostic test versus standard practice: a decision-analytic modeling analysis from a UK healthcare payer perspective

OBJECTIVE

Pre-eclampsia (PE), a leading cause of maternal and perinatal morbidity and mortality, is only detected after symptomatic onset. Early diagnosis may be possible with a new serum test, with resulting clinical and economic benefits versus standard practice. The authors evaluated the financial impact to the UK National Health Service (NHS).

METHODS

A decision-analytic model was developed in which a cohort of 1,000 pregnant women receiving UK obstetric care was simulated. The economic impact of improved sensitivity and specificity of the novel PE test [Roche Diagnostics, Rotkreuz, Switzerland] over current diagnostic practice was modeled. While there is no specific approved diagnostic test to detect PE, physicians are using a combination of tests including blood pressure, proteinuria, Doppler, serum uric acid, etc. The novel PE test constitutes two novel biomarkers Placenta Growth Factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) which can be quantitatively analyzed using an automated system widely available in hospitals or laboratories (Elecsys/Cobas, Roche Diagnostics) and measures the levels of PlGF and sFlt-1 growth factors in pregnant women. The analysis assumed administration of the £31.13 test (the equivalent of 52 Swiss Francs [CHF]) after 20 weeks of gestation as an addition to current practice. True-positive and false-negative patients were assumed to develop mild or severe PE, eclampsia, or death. A hybrid research approach was adopted; when available, data for model inputs were obtained from published literature and public databases. Interviews with obstetricians, laboratory managers, and healthcare payers were used to validate model inputs and fill utilization-related data gaps.

RESULTS

The model estimates that the costs associated with managing a typical pregnancy are £1,781 per patient when the new test is used versus £2,726 with standard practice. This represents savings of £945 per pregnant woman, if the test is used as a supplementary diagnostic tool. The savings are attributed to the new test's improved performance and its ability to better classify the pregnant patients.

CONCLUSIONS

The novel test has the potential to provide substantial cost savings for NHS. Even when the novel test's cost is added to the current cost of care, the benefits exceed the additional cost, driven by the test's ability to reduce the rates of false-positive and false-negative diagnoses compared to current standard of care. Potential study limitations include the use of a pooled average of the individual sensitivities and specificities of currently used tests since no data were available on combination testing, the reliance on clinical trial data versus actual practice, and the use of clinical expert opinion when published data were unavailable.

A prospective cohort study of the value of maternal plasma concentrations of angiogenic and anti-angiogenic factors in early pregnancy and midtrimester in the identification of patients destined to develop preeclampsia

OBJECTIVE

Changes in the maternal plasma concentrations of angiogenic (placental growth factor (PlGF) and vascular endothelial growth factor (VEGF)) and anti-angiogenic factors (sEng and vascular endothelial growth factor receptor-1 (sVEGFR-1)) precede the clinical presentation of preeclampsia. This study was conducted to examine the role of maternal plasma PlGF, sEng, and sVEGFR-1 concentrations in early pregnancy and midtrimester in the identification of patients destined to develop preeclampsia.

METHODS

This longitudinal cohort study included 1622 consecutive singleton pregnant women. Plasma samples were obtained in early pregnancy (6-15 weeks) and midtrimester (20-25 weeks). Maternal plasma PlGF, sEng, and sVEGFR-1 concentrations were determined using sensitive and specific immunoassays. The primary outcome was the development of preeclampsia. Secondary outcomes included term, preterm, and early-onset preeclampsia. Receiving operating characteristic curves, sensitivity, specificity, positive and negative likelihood ratios, and multivariable logistic regression were applied. A p-value of <0.05 was considered significant.

RESULTS

(1) The prevalence of preeclampsia, term, preterm, (<37 weeks) and early-onset preeclampsia (<34 weeks) was 3.8 (62/1622), 2.5 (40/1622), 1.4 (22/1622) and 0.6% (9/1622), respectively; (2) Higher likelihood ratios were provided by ratios of midtrimester plasma concentrations of PlGF, sEng, and sVEGFR-1 than single analytes; (3) Individual angiogenic and anti-angiogenic factors did not perform well in the identification of preeclampsia as a whole; in particular, they perform poorly in the prediction of term preeclampsia; (4) In contrast, a combination of these analytes such as the PlGF/sEng ratio, its delta and slope had the best predictive performance with a sensitivity of 100%, a specificity of 98-99%, and likelihood ratios for a positive test of 57.6, 55.6 and 89.6, respectively, for predicting early-onset preeclampsia.

CONCLUSIONS

(1) The PlGF/sEng ratio and its delta and slope had an excellent predictive performance for the prediction of early-onset preeclampsia, with very high likelihood ratios for a positive test result and very low likelihood ratios for a negative test result; and (2) Although the positive likelihood ratios are high and the positive predictive values low, the number of patients needed to be closely followed is 4:1 for the PlGF/sEng ratio and 3:1 for the slope of PlGF/sEng.

Maternal serum placental growth factor at 11 + 0 to 13 + 6 weeks of gestation in the prediction of pre-eclampsia

OBJECTIVE

To investigate the potential value of maternal serum placental growth factor (PlGF) in first-trimester screening for pre-eclampsia (PE).

METHODS

The concentration of PlGF at 11 + 0 to 13 + 6 weeks' gestation was measured in samples from 127 pregnancies that developed PE, including 29 that required delivery before 34 weeks (early PE) and 98 with late PE, 88 cases of gestational hypertension (GH) and 609 normal controls. The distributions of PlGF multiples of the median (MoM) in the control and hypertensive groups were compared. Logistic regression analysis was used to determine the factors with a significant contribution for predicting PE.

RESULTS

In the control group significant independent contributions for log PlGF were provided by fetal crown-rump length, maternal weight, cigarette smoking and racial origin, and after correction for these variables the median MoM PlGF was 0.991. In the early-PE and late-PE groups PlGF (0.611 MoM and 0.822 MoM, respectively; P < 0.0001) and pregnancy-associated plasma protein-A (PAPP-A) (0.535 MoM; P < 0.0001 and 0.929 MoM; P = 0.015, respectively) were reduced but in GH (PlGF: 0.966 MoM; PAPP-A: 0.895 MoM) there were no significant differences from controls. Significant contributions for the prediction of PE were provided by maternal characteristics and obstetric history, serum PlGF and uterine artery pulsatility index (PI) and with combined screening the detection rates for early PE and late PE were 90% and 49%, respectively, for a false-positive rate of 10%.

CONCLUSION

Effective screening for PE can be provided by a combination of maternal characteristics and obstetric history, uterine artery PI and maternal serum PlGF at 11 + 0 to 13 + 6 weeks' gestation.