sFlt-1/PlGF ratio test for pre-eclampsia: an economic assessment for the UK

Does the use of angiogenic biomarkers for the management of preeclampsia and fetal growth restriction improve outcomes?: Challenging the current status quo

Monitoring and timing of delivery in preterm preeclampsia and fetal growth restriction is one of the biggest challenges in Obstetrics. Finding the optimal time of delivery of these fetuses usually involves a trade-off between the severity of the disease and prematurity. So far, most clinical guidelines recommend the use of a combination between clinical, laboratory and ultrasound markers to guide the time of delivery. Angiogenic biomarkers, especially placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1), have gained significant attention in recent years for their potential role in the prediction and diagnosis of placenta-related disorders including preeclampsia and fetal growth restriction. Another potential clinical application of the angiogenic biomarkers is for the differential diagnosis of patients with chronic kidney disease, as this condition shares similar clinical features with preeclampsia. Consequently, angiogenic biomarkers have been advocated as tools for monitoring and deciding the optimal time of the delivery of fetuses affected by placental dysfunction. In this clinical opinion, we critically review the available literature on PlGF and sFlt-1 for the surveillance and time of the delivery in fetuses affected by preterm preeclampsia and fetal growth restriction. Moreover, we explore the use of angiogenic biomarkers for the differentiation between chronic kidney disease and superimposed preeclampsia.

Signs or symptoms of suspected preeclampsia - A retrospective national database study of prevalence, costs, and outcomes

BACKGROUND

Most patients with signs or symptoms (s/s) of suspected preeclampsia are not diagnosed with preeclampsia. We sought to determine and compare the prevalence of s/s, pregnancy outcomes, and costs between patients with and without diagnosed preeclampsia.

METHODS

This retrospective cohort study analyzed a large insurance research database. Pregnancies with s/s of preeclampsia versus a confirmed preeclampsia diagnosis were identified using International Classification of Diseases codes. S/s include hypertension, proteinuria, headache, visual symptoms, edema, abdominal pain, and nausea/vomiting. Pregnancies were classed as 1) s/s of preeclampsia without a confirmed preeclampsia diagnosis (suspicion only), 2) s/s with a confirmed diagnosis (preeclampsia with suspicion), 3) diagnosed preeclampsia without s/s recorded (preeclampsia only), and 4) no s/s, nor preeclampsia diagnosis (control).

RESULTS

Of 1,324,424 pregnancies, 29.2 % had ≥1 documented s/s of suspected preeclampsia, and 14.2 % received a preeclampsia diagnosis. Hypertension and headache were the most common s/s, leading 20.2 % and 9.2 % pregnancies developed to preeclampsia diagnosis, respectively. Preeclampsia, with or without suspicion, had the highest rates of hypertension-related severe maternal morbidity (HR [95 % CI]: 3.0 [2.7, 3.2] and 3.6 [3.3, 4.0], respectively) versus controls. A similar trend was seen in neonatal outcomes such as preterm delivery and low birth weight. Cases in which preeclampsia was suspected but not confirmed had the highest average total maternal care costs ($6096 [95 % CI: 602, 6170] over control).

CONCLUSION

There is a high prevalence but poor selectivity of traditional s/s of preeclampsia, highlighting a clinical need for improved screening method and cost-effectiveness disease management.

Angiogenic Biomarkers in Preeclampsia

Preeclampsia contributes disproportionately to maternal and neonatal morbidity and mortality throughout the world. A critical driver of preeclampsia is angiogenic imbalance, which is often present weeks to months before overt disease. Two placenta-derived angiogenic biomarkers, soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF), have proved useful as diagnostic and prognostic tests for preeclampsia. Recently, the U.S. Food and Drug Administration approved the sFlt-1/PlGF assay to aid in the prediction of preeclampsia with severe features among women with hypertensive disorders of pregnancy at 24-34 weeks of gestation. In this narrative review, we summarize the body of work leading to this approval and describe how the sFlt-1/PlGF ratio may be implemented in clinical practice as an adjunctive measure to help optimize care and to reduce adverse outcomes in preeclampsia.

Translation of mechanistic advances in preeclampsia to the clinic: Long and winding road

As one of the leading causes of premature birth and maternal and infant mortality worldwide, preeclampsia remains a major unmet public health challenge. Preeclampsia and related hypertensive disorders of pregnancy are estimated to cause >75 000 maternal and 500 000 infant deaths globally each year. Because of rising rates of risk factors such as obesity, in vitro fertilization and advanced maternal age, the incidence of preeclampsia is going up with rates ranging from 5% to 10% of all pregnancies worldwide. A major discovery in the field was the realization that the clinical phenotypes related to preeclampsia, such as hypertension, proteinuria, and other adverse maternal/fetal events, are due to excess circulating soluble fms-like tyrosine kinase-1 (sFlt-1, also referred to as sVEGFR-1). sFlt-1 is an endogenous anti-angiogenic protein that is made by the placenta and acts by neutralizing the pro-angiogenic proteins vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). During the last decade, this work has spawned a new era of molecular diagnostics for early detection of this condition. Antagonizing sFlt-1 either by reducing production or blocking its actions has shown salutary effects in animal models. Further, in early-stage human studies, the therapeutic removal of sFlt-1 from maternal circulation has shown promise in delaying disease progression and improving outcomes. Recently, the FDA approved the first molecular test for preterm preeclampsia (sFlt-1/PlGF ratio) for clinical use in the United States. Measuring serum sFlt-1/PlGF ratio in the acute hospital setting may aid short-term management, particularly regarding step-up or step-down of care, decision to transfer to settings better equipped to manage both the mother and the preterm neonate, appropriate timing of administration of steroids and magnesium sulfate, and in expectant management decisions. The test itself has the potential to save lives. Furthermore, the availability of a molecular test that correlates with adverse outcomes has set the stage for interventional clinical trials testing treatments for this disorder. In this review, we will discuss the role of circulating sFlt-1 and related factors in the pathogenesis of preeclampsia and specifically how this discovery is leading to concrete advances in the care of women with preeclampsia.

The role of the soluble fms-like tyrosine kinase-1/placental growth factor (sFlt-1/PIGF) - ratio in clinical practice in obstetrics: diagnostic and prognostic value

OBJECTIVES

Analyze the diagnostic and prognostic value of the sFlt-1/PlGF ratio in pregnant women with at least one sign/symptom of suspected/diagnosed pre-eclampsia.

METHODS

This retrospective observational study included 170 pregnant women with at least one sign/symptom of pre-eclampsia, who had sFlt-1/PlGF ratio values. The following information was evaluated: pregnant women's demographic data and clinical history; laboratory data (urine protein/creatinine ratio; sFlt-1/PlGF ratio); signs and symptoms presented; clinical outcome; fetal complications; data related to childbirth. Statistical analysis was performed by R Software Version 3.5.2.

RESULTS

Among the 170 patients, 78 presented pre-eclampsia. The median sFlt-1/PlGF ratio was significantly higher [143.1 (2.2-2,927.1)] for women who presented pre-eclampsia than for women without pre-eclampsia [33.5 (0.8-400.2)]. The negative predictive value of sFlt-1/PlGF ratio <38 was 83.9 % (95 % CI, 71.7-92.4 %) and the positive predictive value of sFlt-1/PlGF ratio >85 or 110 (for late onset pre-eclampsia) was 76.4 % (95 % CI, 66.2-84.8 %). sFlt-1/PlGF >85 or 110 was associated with pre-eclampsia clinical development, fetal complications, shorter gestational age at birth, higher number of caesarean deliveries and lower birth weight.

CONCLUSIONS

The sFlt-1/PlGF ratio, together with the standard diagnostic criteria, can be used to rule out pre-eclampsia, identify high-risk patients and predict the occurrence of adverse outcomes.

Placental Growth Factor (PlGF)- Based Biomarker Testing to Help Diagnose Pre-eclampsia in People With Suspected Pre-eclampsia: A Health Technology Assessment

Background

Pre-eclampsia is a potentially serious condition affecting up to 5% of pregnancies, most frequently after 20 weeks' gestation. Placental growth factor (PlGF)-based tests measure either the blood level of PlGF or the ratio of soluble fms-like tyrosine kinase-1 (sFlt-1) to PlGF. They are intended to complement standard clinical assessment to help diagnose pre-eclampsia in people with suspected pre-eclampsia. We conducted a health technology assessment of PlGF-based biomarker testing as an adjunct to standard clinical assessment to help diagnose pre-eclampsia in pregnant people with suspected pre-eclampsia, which included an evaluation of diagnostic accuracy, clinical utility, cost-effectiveness, the budget impact of publicly funding PlGF-based biomarker testing, and an assessment of preferences and values.

Methods

We performed a systematic literature search of the clinical evidence. We assessed the risk of bias of each included study using AMSTAR 2, Cochrane Risk of Bias tool, the Quality of Diagnostic Accuracy Studies 2 (QUADAS-2) tool, and the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic literature search of the economic evidence. We did not conduct a primary economic evaluation as the impact of the test on maternal and neonatal outcomes is uncertain. We also analyzed the budget impact of publicly funding PlGF-based biomarker testing in pregnant people with suspected pre-eclampsia in Ontario. To contextualize the potential value of PlGF-based biomarker testing, we spoke with people whose pregnancies had been impacted by pre-eclampsia as well as their family members.

Results

We included one systematic review and one diagnostic accuracy study in the clinical evidence review. The Elecsys sFlt-1/PlGF ratio test using a test cut-off of less than 38 for ruling out pre-eclampsia within 1 week yielded a negative predictive value (NPV) of 99.2% and the DELFIA Xpress PlGF 1-2-3 test using a cut-off of 150 pg/mL or greater for ruling out pre-eclampsia within 1 week yielded a NPV of 94.8% (diagnostic GRADE: Moderate for both tests). All clinical utility outcomes were associated with uncertainties (GRADE: Low).We included 13 studies in the economic evidence review, most of which concluded that the use of PlGF-based biomarker testing resulted in cost savings. Seven studies were partially applicable to the Ontario health care setting but have some important limitations; the remaining 6 studies were not applicable. We estimated that publicly funding PlGF-based biomarker testing for people with suspected pre-eclampsia in Ontario would lead to an additional annual cost of $0.27 million in year 1 to $0.46 million in year 5, for a total additional cost of $1.83 million over 5 years.Direct engagement included 24 people who had been impacted by pre-eclampsia during their pregnancies as well as one family member. Participants described the emotional and physical impacts of having suspected pre-eclampsia and subsequent treatments. Those that we spoke with valued shared decision-making and identified potential gaps in patient education, specifically as it relates to symptom management for suspected pre-eclampsia. Overall, the participants viewed PlGF-based biomarker testing positively for its perceived medical benefits and minimal invasiveness. They felt that access to PlGF-based biomarker testing may also improve health outcomes through improved patient education, care coordination, and patient-centred care (e.g., prompting more frequent prenatal monitoring, when needed). In addition, PlGF-based biomarker testing was perceived to be equally beneficial for family members who may act as the health care proxy in an emergency. Lastly, participants emphasized that there should be equitable access to PlGF-based biomarker testing and support from a care provider should be offered when trying to interpret the results, particularly if the results are accessible through an online patient portal.

Conclusions

Compared with standard clinical assessment alone in people with suspected pre-eclampsia (gestational age between 20 and 36 weeks + 6 days), PlGF-based biomarker testing as an adjunct to standard clinical assessment likely improves prediction of pre-eclampsia. It may also reduce time to pre-eclampsia diagnosis, severe adverse maternal outcomes, and length of stay in the neonatal intensive care unit, although the evidence is uncertain. PlGF-based biomarker testing may result in little to no difference in other clinical outcomes such as maternal admission to hospital and perinatal adverse outcomes.The economic literature review showed that PlGF-based biomarker testing was cost-effective for use in people with suspected pre-eclampsia, but with some uncertainties. A primary economic evaluation was not done for this health technology assessment because the impact of the test on maternal and neonatal outcomes is uncertain. Publicly funding PlGF-based biomarker testing for people with suspected pre-eclampsia would lead to an additional cost of $1.83 million over 5 years.Publicly funding PlGF-based biomarker testing was viewed favourably by people directly impacted by pre-eclampsia as well as their family members. Those with whom we spoke valued testing to help diagnose suspected pre-eclampsia and valued the potential medical benefits. Participants emphasized that patient education, and equitable access to PlGF-based biomarker testing should be requirements for implementation in Ontario.

Economic Impact Analysis of Incorporation of Elecsys sFlt-1/PlGF Ratio Into Routine Practice for the Diagnosis and Follow-Up of Pregnant Women With Suspected Preeclampsia in Argentina

OBJECTIVES

Preeclampsia (PE) is a hypertensive disorder of pregnancy that can cause severe complications and adverse fetal/maternal outcomes. We aimed to estimate the annual economic impact of incorporating Elecsys® sFlt-1/PlGF PE ratio, which measures soluble fms-like tyrosine kinase-1 and placental growth factor, into routine clinical practice in Argentina to aid diagnosis of PE and hemolysis, elevated liver enzymes, and low platelets syndrome from second trimester onward in pregnancies with clinical suspicion of PE.

METHODS

A decision tree was used to estimate annual economic impact on the Argentine health system as a whole, including relevant costs associated with diagnosis, follow-up, and treatment from initial presentation of clinically suspected PE to delivery. Annual costs of a standard-of-care scenario and a scenario including PE ratio (reference year 2021) were analyzed.

RESULTS

The economic model estimated that using the sFlt-1/PlGF ratio would enable the overall health system to save ∼$6987 million Argentine pesos annually (95% confidence interval $12 045-$2952 million), a 39.1% reduction in costs versus standard of care, mainly due to reduced hospitalizations of women with suspected PE. The economic impact calculation estimated net annual savings of approximately $80 504 Argentine pesos per patient with suspected PE. Based on the assumed uncertainty of the parameters, the likelihood the intervention would be cost saving was 100% for the considered scenarios.

CONCLUSION

Our analysis suggests that the implementation of the sFlt-1/PlGF ratio in women with suspected PE in Argentina will enable the health system to achieve significant savings, contributing to more efficient clinical management through the likely reduction of unnecessary hospitalizations, depending on assumptions. Results rest on the payers' ability to recover savings generated by the intervention.

The predictive value of the sFlt-1/PlGF ratio in suspected preeclampsia in a New Zealand population: A prospective cohort study

BACKGROUND

Internationally, placental growth factor (PlGF)-based tests are used as prognostic markers in suspected preeclampsia. However, Ministry of Health guidelines do not currently endorse PlGF-based tests in New Zealand (NZ).

AIMS

To investigate the predictive value of soluble fms-like tyrosine kinase 1 (sFlt-1)/PlGF ratio in suspected preeclampsia in a NZ population.

MATERIALS AND METHODS

A prospective cohort study of singleton pregnancies at 20⁺⁰ -36⁺⁶ weeks gestation with suspected preeclampsia as defined by Society of Obstetric Medicine Australia and NZ (SOMANZ) criteria.

PRIMARY OBJECTIVE

to evaluate a sFlt-1/PlGF ratio >38 at ≤35⁺⁰ weeks gestation to predict birth ≤14 days.

SECONDARY OBJECTIVES

to assess a sFlt-1/PlGF ratio cut-off of 38 at ≤37⁺⁰ weeks gestation, to rule out preeclampsia ≤1 week, rule in preeclampsia ≤4 weeks, and to predict perinatal outcome. Clinicians were blinded to sFlt-1/PlGF ratio results.

RESULTS

Included were 222 participants, 19.4% Māori and 10.4% Pasifika. A sFlt-1/PlGF >38 predicted birth ≤14 days, positive predictive value (PPV) 51.4% (95% CI, 39.6-63.0) and negative predictive value (NPV) 95.9% (95% CI, 91.4-98.1), median (interquartile range) days to birth 14 (2-27) vs 49 (33-70), P < 0.000. A sFlt-1/PlGF cut-off of 38 ruled out preeclampsia ≤1 week (NPV 96.2% (95% CI, 92.3-98.2)) and ruled in preeclampsia ≤4 weeks (PPV 75.0% (95% CI, 65.0-82.9)). A sFlt-1/PlGF >38 was associated with greater perinatal morbidity.

CONCLUSIONS

The predictive value of the sFlt-1/PlGF ratio in NZ is comparable to that reported in international trials. Used in clinical practice the sFlt-1/PlGF ratio may aid risk stratification in suspected preeclampsia, directing limited resources to those pregnancies at highest risk.

Predictive Model for Preeclampsia Combining sFlt-1, PlGF, NT-proBNP, and Uric Acid as Biomarkers

N-terminal pro-brain natriuretic peptide (NT-proBNP) and uric acid are elevated in pregnancies with preeclampsia (PE). Short-term prediction of PE using angiogenic factors has many false-positive results. Our objective was to validate a machine-learning model (MLM) to predict PE in patients with clinical suspicion, and evaluate if the model performed better than the sFlt-1/PlGF ratio alone. A multicentric cohort study of pregnancies with suspected PE between 24+0 and 36+6 weeks was used. The MLM included six predictors: gestational age, chronic hypertension, sFlt-1, PlGF, NT-proBNP, and uric acid. A total of 936 serum samples from 597 women were included. The PPV of the MLM for PE following 6 weeks was 83.1% (95% CI 78.5−88.2) compared to 72.8% (95% CI 67.4−78.4) for the sFlt-1/PlGF ratio. The specificity of the model was better; 94.9% vs. 91%, respectively. The AUC was significantly improved compared to the ratio alone [0.941 (95% CI 0.926−0.956) vs. 0.901 (95% CI 0.880−0.921), p < 0.05]. For prediction of preterm PE within 1 week, the AUC of the MLM was 0.954 (95% CI 0.937−0.968); significantly greater than the ratio alone [0.914 (95% CI 0.890−0.934), p < 0.01]. To conclude, an MLM combining the sFlt-1/PlGF ratio, NT-proBNP, and uric acid performs better to predict preterm PE compared to the sFlt-1/PlGF ratio alone, potentially increasing clinical precision.

Clinical value and cost analysis of the sFlt-1/PlGF ratio in addition to the spot urine protein/creatinine ratio in women with suspected pre-eclampsia: PREPARE cohort study

BACKGROUND

This study investigated the clinical value of adding the sFlt-1/PlGF ratio to the spot urine protein/creatinine ratio (PCr) in women with suspected pre-eclampsia.

METHODS

This was a prospective cohort study performed in a tertiary referral centre. Based on the combination of PCr (< 30) and sFlt-1/PlGF (≤38) results, four groups were described: a double negative result, group A-/-; a negative PCr and positive sFlt-1/PlGF, group B-/+; a positive PCr and negative sFlt-1/PlGF, group C+/-; and a double positive result, group D+/+. The primary outcome was the proportion of false negatives of the combined tests in comparison with PCr alone in the first week after baseline. Secondary, a cost analysis comparing the costs and savings of adding the sFlt-1/PlGF ratio was performed for different follow-up scenarios.

RESULTS

A total of 199 women were included. Pre-eclampsia in the first week was observed in 2 women (2%) in group A-/-, 12 (26%) in group B-/+, 4 (27%) in group C+/-, and 12 (92%) in group D+/+. The proportion of false negatives of 8.2% [95% CI 4.9-13.3] with the PCr alone was significantly reduced to 1.6% [0.4-5.7] by adding a negative sFlt-1/PlGF ratio. Furthermore, the addition of the sFlt-1/PlGF ratio to the spot urine PCr, with telemonitoring of women at risk, could result in a reduction of 41% admissions and 36% outpatient visits, leading to a cost reduction of €46,- per patient.

CONCLUSIONS

Implementation of the sFlt-1/PlGF ratio in addition to the spot urine PCr, may lead to improved selection of women at low risk and a reduction of hospital care for women with suspected pre-eclampsia.

TRIAL REGISTRATION

Netherlands Trial Register (NL8308).

Diagnosis and Management of Preeclampsia: Suggested Guidance on the Use of Biomarkers

OBJECTIVE

 It is a challenge to consider preeclampsia (PE) diagnosis and management in low and middle-income settings, where it represents a major public health concern. The placenta is the underlying cause of disease, and the plasma concentrations of proangiogenic and antiangiogenic factors released by the placenta can reflect the risks of disease progression. Antiangiogenic proteins, such as soluble fms-like tyrosine kinase 1 (sFlt-1), and proangiogenic, like placental growth factors (PlGF), are directly and inversely correlated with the disease onset, respectively.

METHODS

 Narrative review on the use of biomarkers (sFlt-1 to PlGF ratio) with a suggested guidance protocol.

RESULTS

 Key considerations on the use of biomarkers: the sFlt-1/PlGF ratio is mainly relevant to rule out PE between 20 and 36 6/7 weeks in cases of suspected PE; however, it should not replace the routine exams for the diagnosis of PE. The sFlt-1/PlGF ratio should not be performed after confirmed PE diagnosis (only in research settings). In women with suspected PE, sFlt-1/PlGF ratio < 38 can rule out the diagnosis of PE for 1 week (VPN = 99.3) and up to 4 weeks (VPN= 94.3); sFlt-1/PlGF ratio > 38 does not confirm the diagnosis of PE; however, it can assist clinical management. In cases of severe hypertension and/or symptoms (imminent eclampsia), hospitalization is imperative, regardless of the result of the sFlt-1/PlGF ratio.

CONCLUSION

 The use of biomarkers can help support clinical decisions on the management of suspected PE cases, especially to rule out PE diagnosis, thus avoiding unnecessary interventions, especially hospitalizations and elective prematurity.

sFlt-1/PlGF ratio for prediction of preeclampsia in clinical routine: A pragmatic real-world analysis of healthcare resource utilisation

Background

We investigated the impact of the soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio to predict short-term risk of preeclampsia on clinical utility and healthcare resource utilisation using real-world data (RWD), and compared findings with health economic modelling from previous studies.

Methods and findings

This retrospective analysis compared data from the German population of a multicentre clinical study (PROGNOSIS, n = 203; sFlt-1/PlGF ratio blinded and unavailable for decision-making) with RWD from University Hospital Leipzig, Germany (n = 281; sFlt-1/PlGF ratio used to guide clinical decision-making). A subgroup of the RWD cohort with the same inclusion criteria as the PROGNOSIS trial (RWD prediction only, n = 99) was also included. sFlt-1/PlGF ratio was measured using fully automated Elecsys® sFlt-1 and PlGF immunoassays (cobas e analyser; Roche Diagnostics).

A similar proportion of women in the RWD and PROGNOSIS cohorts experienced preeclampsia (14.95% vs. 13.79%; p = 0.7938); a smaller proportion of women in the RWD prediction only cohort experienced preeclampsia versus PROGNOSIS (6.06%; p = 0.0526). In women with preeclampsia, median gestational age at delivery (weeks) was comparable in the RWD and PROGNOSIS cohorts (34.0 vs. 34.3, p = 0.5895), but significantly reduced in the RWD prediction only cohort versus PROGNOSIS (27.1, p = 0.0038). sFlt-1/PlGF ratio at baseline visit was not statistically significantly different for the RWD and PROGNOSIS cohorts, irrespective of preeclampsia outcome. Hospitalisations for confirmed preeclampsia were significantly shorter in the RWD cohort versus PROGNOSIS (median 1 vs. 4 days, p = 0.0093); there was no significant difference between RWD prediction only and PROGNOSIS (3 days, p = 0.9638). All-cause hospitalisations were significantly shorter in the RWD (median 1 day; p<0.0001) and RWD prediction only (1 day; p<0.0001) cohorts versus PROGNOSIS (3 days).

Conclusions

This study supports the findings of previous studies, showing that routine clinical use of the sFlt-1/PlGF ratio may result in shorter duration of hospitalisations, with potential economic benefits.

Imbalances in circulating angiogenic factors in the pathophysiology of preeclampsia and related disorders

Preeclampsia is a devastating medical complication of pregnancy that can lead to significant maternal and fetal morbidity and mortality. It is currently believed that there is abnormal placentation in as early as the first trimester in women destined to develop preeclampsia. Although the etiology of the abnormal placentation is being debated, numerous epidemiologic and experimental studies suggest that imbalances in circulating angiogenic factors released from the placenta are responsible for the maternal signs and symptoms of preeclampsia. In particular, circulating levels of soluble fms-like tyrosine kinase 1, an antiangiogenic factor, are markedly increased in women with preeclampsia, whereas free levels of its ligand, placental, growth factor are markedly diminished. Alterations in these angiogenic factors precede the onset of clinical signs of preeclampsia and correlate with disease severity. Recently, the availability of automated assays for the measurement of angiogenic biomarkers in the plasma, serum, and urine has helped investigators worldwide to demonstrate a key role for these factors in the clinical diagnosis and prediction of preeclampsia. Numerous studies have reported that circulating angiogenic biomarkers have a very high negative predictive value to rule out clinical disease among women with suspected preeclampsia. These blood-based biomarkers have provided a valuable tool to clinicians to accelerate the time to clinical diagnosis and minimize maternal adverse outcomes in women with preeclampsia. Angiogenic biomarkers have also been useful to elucidate the pathogenesis of related disorders of abnormal placentation such as intrauterine growth restriction, intrauterine fetal death, twin-to-twin transfusion syndrome, and fetal hydrops. In summary, the discovery and characterization of angiogenic proteins of placental origin have provided clinicians a noninvasive blood-based tool to monitor placental function and health and for early detection of disorders of placentation. Uncovering the mechanisms of altered angiogenic factors in preeclampsia and related disorders of placentation may provide insights into novel preventive and therapeutic options.

The diagnostic value of angiogenic and antiangiogenic factors in differential diagnosis of preeclampsia

The definition of preeclampsia is changing. However, with the addition of organ symptoms to the presence of hypertension in pregnancy instead of relying only on proteinuria, a more precise detection of women at risk of preeclampsia-associated adverse events has not been achieved. Instead, under the new definitions of the American College of Obstetricians and Gynecologists and of the International Society for the Study of Hypertension in Pregnancy, more women are classified as preeclamptic, with a tendency to milder disease. Furthermore, angiogenic and antiangiogenic factors have emerged as essential tools for predicting and diagnosing preeclampsia at high accuracies. Next to being rooted in the pathophysiology of the disease, they have been proven to be reliable tools for predicting and diagnosing the disease. In addition, 2 cutoffs have been evaluated for the clinical setting. As shown in the Prediction of Short-Term Outcome in Pregnant Women With Suspected Preeclampsia Study, at the soluble fms-like tyrosine kinase-1-to-placental growth factor ratio cutoff of 38, a preeclampsia can be ruled out for 1 week with a negative predictive value of 99.3% (95% confidence interval, 97.9-99.9) and ruled in with a positive predictive value of 36.7% (95% confidence interval, 28.4-45.7). The diagnostic cutoff of 85 has been shown to accurately identify women with preeclampsia, with a sensitivity of up to 88% and a specificity of 99.5%. In this review, we highlight the central role of angiogenic and antiangiogenic factors in the differential diagnosis of women presenting at high risk of the disease, such as patients with chronic hypertension or chronic kidney disease. We will focus on their ability to predict preeclampsia-associated adverse fetal and maternal outcomes. This is only possible when critically reviewing the evolution of the definition of "preeclampsia." We show how changes in this definition shape our clinical picture of the condition and how angiogenic and antiangiogenic biomarkers might be included to better identify women destined to develop preeclampsia-related adverse outcomes.

Cost effectiveness of the sFlt1/PlGF ratio test as an adjunct to the current practice of evaluating suspected preeclampsia in the United States

OBJECTIVE

Preeclampsia is a major obstetric disorder that can lead to severe maternal, fetal and infant outcomes. In women with suspected preeclampsia, measurement of the soluble fms-like tyrosine kinase-1 (sFlt1) and placental growth factor (PlGF) ratio has been shown to have a high negative predictive value (>97%). Our aim was to estimate the value to the US healthcare system of adopting this test into clinical practice.

STUDY DESIGN

An economic model was developed for the evaluation of suspected preeclampsia from a US payer perspective using data from a US observational study of 459 women evaluated between 23 and 34.6 weeks. Test results were not available to clinicians. The model compares two strategies for managing suspected preeclampsia: standard care versus a biomarker-informed pathway utilizing the sFlt1/PlGF ratio.

RESULTS

Utilization of the sFlt1/PlGF ratio test reduced the number of women admitted for suspected preeclampsia by 34-49%. Despite fewer admissions, a higher proportion of women admitted to hospital subsequently developed preeclampsia, and the proportion of women not admitted who would subsequently develop preeclampsia remained low (3.2%-6.7%). Cost savings arising from a reduction in admissions are estimated to be $1050 in the base case; varying the hospitalization cost ±25% would lead to savings in the range $771 to $1330 per patient at 2020 prices.

CONCLUSION

Adopting the sFlt1/PlGF ratio test as an adjunct to clinical criteria improves the assessment of risk in women presenting with suspicion of preeclampsia and has the potential to safely reduce unnecessary admissions and save costs.

Implementing placental-growth-factor (PLGF) measurements in suspected pre-eclampsia----Challenges in clinical practice

OBJECTIVES

As a part of NHS' Innovation and Technology Payment programme (ITP), pregnant women were offered Placental Growth Factor (PLGF)-based testing to help rule out pre-eclampsia (PET) - a serious condition that affects approximately 2.3% of the female population. The study was aimed to evaluate the implementation of PLGF-based testing at United Lincolnshire Trust Hospitals (ULHT).

STUDY DESIGN

The soluble FMS like Tyrosine kinase 1/placental growth factor (sFlt-1/PLGF) ratio test was launched at ULHT on 8th October 2020. The project involved a review of an electronic maternity database (MEDWAY) for all women who had sFLT-1/PLGF ratio test performed at ULHT over a 5-month period (October 2020-February 2021). The sFlt-1/PLGF ratio was recorded alongside clinical outcome. Women were classified as low, moderate, and high risk for development of PET if the sFlt-1/PLGF ratio was ≤ 38, 39-84 and ≥ 85 respectively. Reasons for admission were further investigated and adherence to the sFLT-1/PLGF protocol was monitored to evaluate staff performance. Data was then statistically analysed with χ2 and T-test for categorical and continuous variables respectively. Finally, sensitivity and specificity of the sFLT-1/PLGF was assessed with an ROC curve.

RESULTS

A total of 236 women had sFlt-1/PLGF ratio test performed in a five-month period. A two-time point analysis (a "during implementation" and "post implementation phase") showed a significant decrease in the admission rates in the post-implementation phase in low-risk group (28.5% during implementation vs 11.3% post-implementation, P < 0.05). Further analysis showed greater staff adherence to the sFLT-1/PLGF protocol in the post-implementation period. The high-risk group demonstrated shorter time from test to delivery, earlier gestational age at delivery and lower birth weight (P < 0.05).

CONCLUSIONS

The study outcomes resulted in a successful submission of a business case. Successful triage of low-risk women at the point where historically admissions were considered reduced clinical workload and enabled better utilisation of resources by allowing focussed care on high-risk women for an optimal maternal and perinatal outcome.

Decision Threshold for Kryptor sFlt-1/PlGF Ratio in Women With Suspected Preeclampsia: Retrospective Study in a Routine Clinical Setting

Background The objective was to evaluate predictive performance and optimal decision threshold of the Kryptor soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio when implemented for routine management of women presenting with symptoms of preeclampsia. Methods and Results Observational retrospective study of a cohort of 501 women with suspected preeclampsia after 20 weeks of gestation. Women referred to maternity ward for observation of preeclampsia had an sFlt-1/PlGF ratio test included in routine diagnostic workup. Maternal and offspring characteristic data included maternal risk factors, outcomes, delivery mode, and indication for suspected preeclampsia. Biochemical measurements to determine sFlt-1/PlGF ratio were performed using the BRAHMS/Kryptor sFlt-1/PlGF ratio immunoassays. Results were analyzed by area under receiver-operating characteristic curve. Preeclampsia occurred in 150 of 501 (30%) of symptomatic women with an sFlt-1/PlGF ratio determined before the time of diagnosis. Area under receiver-operating characteristic curve for diagnosis of early-onset preeclampsia within 1 and 4 weeks was 0.98 (95% CI, 0.96-1.00) and 0.95 (95% CI, 0.92-0.98), respectively. For late-onset preeclampsia, predictive performance within 1 and 4 weeks was lower: 0.90 (95% CI, 0.85-0.94) and 0.85 (95% CI, 0.80-0.90), respectively. The optimal single sFlt-1/PlGF ratio threshold for all preeclampsia and late-onset preeclampsia within 1 and 4 weeks was 66. The negative and positive predictive values for ruling out and ruling in developing preeclampsia within 1 week were 96% and 70%, respectively. Conclusions The Kryptor sFlt-1/PlGF ratio is a useful clinical tool ruling out and in preeclampsia within 1 week. Prediction within 4 weeks is superior for early-onset preeclampsia. A single decision threshold of 66 is indicated for use in clinical routine.

Enhancing the value of the sFlt-1/PlGF ratio for the prediction of preeclampsia: Cost analysis from the Belgian healthcare payers' perspective

OBJECTIVE

To evaluate the economic impact of introducing the soluble fms-like tyrosine kinase (sFlt-1) to placental growth factor (PlGF) ratio test into clinical practice in Belgium for the prediction of preeclampsia (PE).

STUDY DESIGN

We developed a one-year time-horizon decision tree model to evaluate the short-term costs associated with the introduction of the sFlt-1/PlGF test for guiding the management of women with suspected PE from the Belgian public healthcare payers' perspective. The model estimated the costs associated with the diagnosis and management of PE in pregnant women managed in either a test scenario, in which the sFlt-1/PlGF test is used in addition to current clinical practice, or a no test scenario, in which clinical decisions are based on current practice alone. Test characteristics were derived from PROGNOSIS, a non-interventional study in women presenting with clinical suspicion of PE. Unit costs were obtained from Belgian-specific sources. The main model outcome was the total cost per patient.

RESULTS

Introduction of the sFlt-1/PlGF ratio test is expected to result in a cost saving of €712 per patient compared with the no test scenario. These savings are generated mainly due to a reduction in unnecessary hospitalizations.

CONCLUSIONS

The sFlt-1/PlGF test is projected to result in substantial cost savings for the Belgian public healthcare payers through reduction of unnecessary hospitalization of women with clinical suspicion of PE that ultimately do not develop the condition. The test also has the potential to ensure that women at high risk of developing PE are identified and appropriately managed.

Economic evaluation of the sFlt-1/PlGF ratio for the short-term prediction of preeclampsia in a Japanese cohort of the PROGNOSIS Asia study

The PRediction of short-term Outcomes in preGNant wOmen with Suspected preeclampsIa Study (PROGNOSIS) Asia validated the use of the soluble fms-like tyrosine 1/placental growth factor (sFlt-1/PlGF) ratio cutoff value of ≤38 to rule out the occurrence of preeclampsia in the short term in Asian women. We assessed the economic impact of the introduction of the sFlt-1/PlGF ratio test for predicting preeclampsia in Japan using data from the Japanese cohort of PROGNOSIS Asia. The cost analysis was developed with estimates in either a no-test scenario, with clinical decisions based on standard diagnostic procedures alone, or a test scenario, in which the sFlt-1/PlGF ratio test was used in addition to standard diagnostic procedures. For both scenarios, rates of hospitalization and other test characteristics were obtained from the results for the Japanese cohort in PROGNOSIS Asia. The total cost per patient was the main outcome of this cost analysis model. Introduction of the sFlt-1/PlGF ratio test using a cutoff value of 38 resulted in a reduced hospitalization rate compared with the rate in the no-test scenario (14.4% versus 8.7%). The reduction in the rate of hospitalizations led to an estimated 16 373 JPY reduction in healthcare costs per patient. The sFlt-1/PlGF ratio test is likely to reduce the unnecessary hospitalization of women at low risk of developing preeclampsia in the short term while also identifying high-risk individuals requiring appropriate management. Reducing unnecessary hospitalizations would result in significant cost savings in the Japanese healthcare system.

Astragaloside IV ameliorates preeclampsia-induced oxidative stress through the Nrf2/HO-1 pathway in a rat model

Preeclampsia (PE) can cause serious health problems for pregnant women and their infants. Astragaloside IV has been shown to exert cardioprotective, anti-inflammatory, and antioxidative effects on various disorders. We aimed to study the effects of Astragaloside IV on PE symptoms using an N^G-nitro-l-arginine methyl ester (l-NAME)-induced rat model of PE. The pregnant rats' physiological features, including blood pressure, urine protein, serum soluble fms-like tyrosine kinase-1(sFlt-1)/placental growth factor (PlGF) ratio, and weight of placenta, as well as the weight, length, and survival of pups, were documented. The expression levels of target genes were analyzed by Western blot and qRT-PCR assays. The levels of target secreted proteins were determined by ELISA. We demonstrated that the administration of Astragaloside IV might exert a multitude of beneficial effects on attenuated PE symptoms in a rat model of PE. We further revealed that the effects of Astragaloside IV on PE rats were achieved, at least partially, through elimination of oxidative stress and stimulation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway. Our study indicated that Astragaloside IV may serve as a promising candidate for the development of new therapeutic methods for patients with PE.

Costing the impact of interventions during pregnancy in the UK: a systematic review of economic evaluations

OBJECTIVE

The aim of this review was to summarise the current evidence on the costing of resource use within UK maternity care, in order to facilitate the estimation of incremental resource and cost impacts potentially attributable to maternity care interventions.

METHODS

A systematic review of economic evaluations was conducted by searching Medline, the Health Management Information Consortium, the National Health Service (NHS) Economic Evaluations Database, CINAHL and National Institute for Health and Care Excellence (NICE) guidelines for economic evaluations within UK maternity care, published between January 2010 and August 2019 in the English language. Unit costs for healthcare activities provided to women within the antenatal, intrapartum and postnatal period were inflated to 2018-2019 prices. Assessment of study quality was performed using the Quality of Health Economic Analyses checklist.

RESULTS

Of 5084 titles or full texts screened, 37 papers were included in the final review (27 primary research articles, 7 review articles and 3 economic evaluations from NICE guidelines). Of the 27 primary research articles, 21 were scored as high quality, 3 as medium quality and 3 were low quality. Variation was noted in cost estimates for healthcare activities throughout the maternity care pathway: for midwife-led outpatient appointment, the range was £27.34-£146.25 (mean £81.78), emergency caesarean section, range was £1056.44-£4982.21 (mean £3508.93) and postnatal admission, range was £103.00-£870.10 per day (mean £469.55).

CONCLUSIONS

Wide variation exists in costs applied to maternity healthcare activities, resulting in challenges in attributing cost to maternity activities. The level of variation in cost calculations is likely to reflect the uncertainty within the system and must be dealt with by conducting sensitivity analyses. Nationally agreed prices for granular unit costs are needed to standardise cost-effectiveness evaluations of new interventions within maternity care, to be used either for research purposes or decisions regarding national intervention uptake.

PROSPERO REGISTRATION NUMBER

CRD42019145309.

Placental growth factor as a predictive marker of preeclampsia - PREBIO study - PREeclampsia BIOchemical study

INTRODUCTION

To evaluate the clinical utility of placental growth factor (PlGF) for the prediction of preeclampsia (PE).

MATERIALS AND METHODS

This prospective cohort study included women divided into three groups: (1) pregnancies without preconceptional risk of developing PE; (2) pregnancies with a preconceptional and/or current risk of developing PE; (3) PE-complicated pregnancies (control group). Blood samples were collected every 4-5 weeks or during hospitalization from early second trimester until delivery in the group 1 and 2, at the diagnosis of PE in the group 3. Plasma levels of PlGF were measured using The Triage PlGF test (Alere) and considered pathological under the 5th centile for gestational age. Sensitivity (Sn), specificity (Sp), positive and negative predictive value (PPV, NPV) were calculated.

RESULTS

In group 1, 30% of women (3/10) had pathological test but none of them developed PE (Sp 70%, NPV 100%). In group 2 (n = 75), none of the patients with normal test developed PE (0/24), while 39% of women with PlGF < 5th centile (20/51) developed PE (Sn 100%, Sp 44%, PPV 39%, NPV 100%). In group 3 (n = 11) all women except one had a pathological PlGF test (Sn 90%, PPV 100%).

CONCLUSIONS

Our data support recent studies which identify PlGF as a biochemical marker not only of PE, but also of placental dysfunction. In fact, it is useful for ruling out PE in women at risk because of the high Sn and high NPV: a normal PlGF is related with a positive pregnancy outcome. Therefore, the measurement of this biomarker would simplify PE clinical management and would reduce costs.

sFlt-1/PlGF Ratio as a Predictive Marker in Women with Suspected Preeclampsia: An Economic Evaluation from a Swiss Perspective

In Switzerland, 2.3% of pregnant women develop preeclampsia. Quantification of the soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) ratio has shown a diagnostic value in the second and third trimesters of pregnancy, in particular in ruling out preeclampsia within one week. We estimated the economic impact of implementing sFlt-1/PlGF ratio evaluation, in addition to the standard of care (SOC), for women with suspected preeclampsia from a Swiss healthcare system's perspective. A decision tree model was developed to estimate direct medical costs of diagnosis and management of a simulated cohort of Swiss pregnant women with suspected preeclampsia (median week of gestation: 32) until delivery. The model compared SOC vs. SOC plus sFlt-1/PlGF ratio, using clinical inputs from a large multicenter study (PROGNOSIS). Resource use data and unit costs were obtained from hospital records and public sources. The assumed cost for sFlt-1/PlGF evaluation was €141. Input parameters were validated by clinical experts in Switzerland. The model utilized a simulated cohort of 6084 pregnant women with suspected preeclampsia (representing 7% of all births in Switzerland in 2015, n = 86,919). In a SOC scenario, 36% of women were hospitalized, of whom 27% developed preeclampsia and remained hospitalized until birth. In a sFlt-1/PlGF test scenario, 76% of women had a sFlt-1/PlGF ratio of ≤38 (2% hospitalized), 11% had a sFlt-1/PlGF ratio of >38-<85 (55% hospitalized), and 13% had a sFlt-1/PlGF ratio of ≥85 (65% hospitalized). Total average costs/pregnant woman (including birth) were €10,925 vs. €10,579 (sFlt-1/PlGF), and total costs were €66,469,362 vs. €64,363,060 (sFlt-1/PlGF). Implementation of sFlt-1/PlGF evaluation would potentially achieve annual savings of €2,105,064 (€346/patient), mainly due to reduction in unnecessary hospitalization. sFlt-1/PlGF evaluation appears economically promising in predicting short-term absence of preeclampsia in Swiss practice. Improved diagnostic accuracy and reduction in unnecessary hospitalization could lead to significant cost savings in the Swiss healthcare system.

Randomized Interventional Study on Prediction of Preeclampsia/Eclampsia in Women With Suspected Preeclampsia: INSPIRE

Supplemental Digital Content is available in the text.

The ratio of maternal serum sFlt-1 (soluble fms-like tyrosine kinase 1) to PlGF (placental growth factor) has been used retrospectively to rule out the occurrence of preeclampsia, a pregnancy hypertensive disorder, within 7 days in women presenting with clinical suspicion of preeclampsia. A prospective, interventional, parallel-group, randomized clinical trial evaluated the use of sFlt-1/PlGF ratio in women presenting with suspected preeclampsia. Women were assigned to reveal (sFlt-1/PlGF result known to clinicians) or nonreveal (result unknown) arms. A ratio cutoff of 38 was used to define low (≤38) and elevated risk (>38) of developing the condition in the subsequent week. The primary end point was hospitalization within 24 hours of the test. Secondary end points were development of preeclampsia and other adverse maternal-fetal outcomes. We recruited 370 women (186 reveal versus 184 nonreveal). Preeclampsia occurred in 85 women (23%). The number of admissions was not significantly different between groups (n=48 nonreveal versus n=60 reveal; P=0.192). The reveal trial arm admitted 100% of the cases that developed preeclampsia within 7 days, whereas the nonreveal admitted 83% (P=0.038). Use of the test yielded a sensitivity of 100% (95% CI, 85.8–100) and a negative predictive value of 100% (95% CI, 97.1–100) compared with a sensitivity of 83.3 (95% CI, 58.6–96.4) and negative predictive value of 97.8 (95% CI, 93.7–99.5) with clinical practice alone. Use of the sFlt-1/PlGF ratio significantly improved clinical precision without changing the admission rate.

A Review of Angiogenic Imbalance in HIV-Infected Hypertensive Disorders of Pregnancy

PURPOSE OF REVIEW

This review provides a comprehensive insight into the angiogenic profile of hypertensive and normotensive pregnancies compromised by HIV infection. Furthermore, we evaluate the economic implementation of the sFlt-1/PlGF ratio and review the reports on therapeutic apheresis in limiting sFlt-1 production.

RECENT FINDINGS

In preeclampsia, an increased expression of sFlt-1 triggers angiogenic imbalance. Women of African ancestry have high levels of angiogenic factors than other racial groups. The sFlt-1/PlGF ratio shows promise in the early assessment of preeclampsia, while sFlt-1 apheresis restores angiogenic imbalance. Studies suggest antiretroviral therapy does not impact the angiogenic shift in preeclampsia development. The angiogenic profile in pregnant women of different races influences preeclampsia development. Despite the opposing immune response in HIV infection and preeclampsia, the HIV tat protein strongly mimics vascular endothelial growth factor (VEGF); hence, it is plausible to assume that HIV infection may ameliorate the angiogenic imbalance in preeclampsia.

Placental growth factor testing for suspected pre-eclampsia: a cost-effectiveness analysis

Objective

To calculate the cost‐effectiveness of implementing PlGF testing alongside a clinical management algorithm in maternity services in the UK, compared with current standard care.

Design

Cost‐effectiveness analysis.

Setting

Eleven maternity units participating in the PARROT stepped‐wedge cluster‐randomised controlled trial.

Population

Women presenting with suspected pre‐eclampsia between 20⁺⁰ and 36⁺⁶ weeks’ gestation.

Methods

Monte Carlo simulation utilising resource use data and maternal adverse outcomes.

Main outcome measures

Cost per maternal adverse outcome prevented.

Results

Clinical care with PlGF testing costs less than current standard practice and resulted in fewer maternal adverse outcomes. There is a total cost‐saving of UK£149 per patient tested, when including the cost of the test. This represents a potential cost‐saving of UK£2,891,196 each year across the NHS in England.

Conclusions

Clinical care with PlGF testing is associated with the potential for cost‐savings per participant tested when compared with current practice via a reduction in outpatient attendances, and improves maternal outcomes. This economic analysis supports a role for implementation of PlGF testing in antenatal services for the assessment of women with suspected pre‐eclampsia.

Tweetable abstract

Placental growth factor testing for suspected pre‐eclampsia is cost‐saving and improves maternal outcomes.

Placental growth factor testing for suspected pre‐eclampsia is cost‐saving and improves maternal outcomes.

Is urinary excretion of plasminogen associated with development of pre-eclampsia? An observational, explorative case-control study

OBJECTIVES

Pre-eclampsia (PE) is characterised by renal glomerular endotheliosis and injury to the glomerular filtration barrier with proteinuria. Patients with PE display aberrant filtration of the plasma proenzyme plasminogen which is activated, in the tubular fluid, to plasmin. Plasmin may activate the epithelial sodium channel and cause impaired sodium excretion and contribute to hypertension. An explorative study was conducted to test the association between urinary total plasminogen/plasmin and the development of PE. A positive association was hypothesised.

DESIGN

An observational, explorative, nested case-control study of healthy pregnant women.

SETTINGS

A Danish County hospital. Samples were collected between 2001 and 2004.

PARTICIPANTS

1631 healthy pregnant women participated. Urine samples were collected longitudinally six times during pregnancy. 30 developed PE (cases) and were compared with 146 randomly selected healthy pregnant women (controls).

PRIMARY OUTCOME

The association between total plasminogen/plasmin excreted in the urine and PE development is expressed by ORs. Total urinary excretion of plasminogen/plasmin was defined by the urine plasminogen-plasmin/creatinine ratio.

SECONDARY OUTCOME

The association between urine (u)-albumin/creatinine ratio, u-aldosterone/creatinine ratio and PE development is expressed by ORs. The correlation between urinary (u-) plasmin and u-aldosterone concentration is expressed as a correlation coefficient.

RESULTS

The development of PE in late pregnancy was associated with increased levels of the urine plasminogen-plasmin/creatinine ratio (OR=2.35; 95% CI: 1.12 to 4.93; p<0.05).U-aldosterone/creatinine ratio did not predict PE at any time. U-albumin/creatinine ratio was positively associated with the development of PE from gestational week 33 (OR=14.04; 95% CI: 2.56 to 76.97; p<0.01) and in week 33-35 (OR=14.15; 95% CI: 3.44 to 58.09; p<0.001) and after gestational week 36, respectively.

CONCLUSION

Aberrant filtration of plasminogen may contribute to the pathophysiological features of impaired sodium excretion and hypertension associated with PE late in pregnancy. However, increased urinary albumin levels reveal stronger associations with PE development compared with urinary plasminogen levels.

The role of angiogenic factors in the management of preeclampsia

Preeclampsia is a pregnancy disorder causing substantial maternal and fetal morbidity and mortality. In the UK, its diagnosis currently depends upon new onset hypertension and proteinuria. There is a clinical need for enhanced screening to prevent unnecessary resource use and improve outcomes. Here, the current practice in preeclampsia diagnosis will be summarized, with assessment of the evidence that angiogenic factors could improve its management. Although the combination of new onset hypertension and proteinuria define and hence diagnose the disorder, separately they are poorly predictive. Preeclampsia is ultimately a placental disease caused by syncytiotrophoblast dysfunction. The angiogenic factors placental growth factor, soluble fms-like tyrosine kinase 1 and soluble endoglin, all originating at least in part from the syncytiotrophoblast, are biomarkers with predictive potential for preeclampsia and related adverse outcomes. Recent work with the soluble fms-like tyrosine kinase 1/placental growth factor ratio has identified key measurement cutoffs, with one having a high negative predictive value for preeclampsia. The soluble fms-like tyrosine kinase 1/placental growth factor ratio seems particularly promising as a screening measure, able to predict accurately the short-term absence of preeclampsia and suggest the likelihood of adverse events within 4 weeks. The ratio could be used to allocate specific management plans to patients according to risk. An understanding of angiogenic factors may also lead to new therapeutic options for a condition currently only curable by delivery, although it must be remembered that the factors are markers of underlying syncytiotrophoblast stress, which would not be resolved by targeting them.

Use of the sFlt-1/PlGF ratio to rule out preeclampsia requiring delivery in women with suspected disease. Is the evidence reproducible?

BACKGROUND

Soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) ratio has been proven to predict preeclampsia occurrence.

METHODS

Blood samples from 195 pregnant women with suspected preeclampsia were obtained at obstetric triage admission or from the high-risk pregnancy outpatient office. Serum PlGF and sFlt-1 were measured by an electrochemiluminescence immunoassay (ECLIA) on the immunoanalyser Cobas e601 (Roche Diagnostics) and the corresponding ratio was calculated. Final outcomes were reviewed by an independent obstetrician. Only the first determination was considered.

RESULTS

A sFlt-1/PlGF ratio of 38 or lower ruled out the need for pregnancy termination due to preeclampsia in the subsequent week with a negative predictive value (NPV) of 99.1% (sensitivity 97.1% and specificity 67.5%). None of the 76 pregnancies with first determination of an sFlt-1/PlGF ratio of 38 or lower between 24 and 34 weeks of gestation delivered due to early-onset preeclampsia. Positive likelihood ratio (PLR) of an sFlt-1/PlGF ratio above 38 for prediction of pregnancy termination due to preeclampsia within 4 weeks is analogous to published evidence.

CONCLUSIONS

Between 24 and 34 weeks of gestation, no subsequent determination was needed to completely rule out early-onset preeclampsia when the first sFlt-1/PlGF ratio determination was 38 or lower in singleton pregnancies with signs or symptoms of this syndrome. These findings, if confirmed, will reduce costs and facilitate the implementation of the sFlt-1/PlGF ratio in women with clinical suspicion of preeclampsia in the third trimester.

Economic assessment of the use of the sFlt-1/PlGF ratio test to predict preeclampsia in Germany

Background

The PRediction of short-term Outcome in preGNant wOmen with Suspected preeclampsIa Study (PROGNOSIS) demonstrated that a soluble fms-like tyrosine kinase 1/placental growth factor (sFlt-1/PlGF) ratio ≤ 38 ruled out the occurrence of preeclampsia in the next week with a negative predictive value of 99.3%; a ratio > 38 indicates an increased risk of developing preeclampsia in the next 4 weeks. We performed an assessment of the economic impact of the sFlt-1/PlGF ratio test for short-term prediction of preeclampsia in Germany.

Methods

We adapted a cost-effectiveness model, which had been developed to estimate the incremental value of adding the sFlt-1/PlGF ratio test with a cut-off ratio of 38 to standard diagnostic procedures for guiding the management of women with suspected preeclampsia in the UK. We used the adapted model to estimate the incremental value of the sFlt-1/PlGF ratio test (cut-off 38) for guiding the management of women with suspected preeclampsia from a German Diagnosis-Related Group (DRG) payer perspective. The economic model estimated costs associated with diagnosis and management of preeclampsia in women managed in either a ‘no-test’ scenario in which clinical decisions are based on standard diagnostic procedures alone, or a ‘test’ scenario in which the sFlt-1/PlGF test is used in addition to standard diagnostic procedures. Test characteristics and rates of hospitalization were derived from patient-level data from PROGNOSIS. The main outcome measure from the economic model was the total cost per patient.

Results

In the model adapted to the German DRG payer system, introduction of the sFlt-1/PlGF ratio test with a cut-off value of 38 could reduce the proportion of women hospitalized in Germany from 44.6 to 24.0%, resulting in an expected cost saving of €361 per patient.

Conclusions

The sFlt-1/PlGF ratio test is likely to reduce unnecessary hospitalization of women with a low risk of developing preeclampsia, and identify those at high risk to ensure appropriate management. Even within the restrictions of the DRG system in Germany, this results in substantial cost savings for women with suspected preeclampsia.

Electronic supplementary material

The online version of this article (10.1186/s12913-018-3406-1) contains supplementary material, which is available to authorized users.

Evaluation of sFlt-1/PlGF Ratio for Predicting and Improving Clinical Management of Pre-eclampsia: Experience in a Specialized Perinatal Care Center

Background

Management of pregnant women at high risk of pre-eclampsia (PE) requires frequent monitoring, with referral to specialized perinatal care centers. Reliable tests are necessary to improve prediction of PE and related complications and to assess disease severity and progression. An imbalance in two biomarkers, soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF), is involved in PE pathogenesis. The sFlt-1 to PlGF ratio is increased in pregnant women before the onset of PE. An elevated ratio is highly predictive of PE, whereas the diagnosis of PE can be ruled out within one week for low ratios. The main objective of this study was to assess whether a low sFlt-1/PlGF ratio, below a cutoff of 38, can predict the absence of PE within one week.

Methods

We performed a prospective, monocentric, observational study to evaluate serum sFlt-1/PlGF ratio (Roche Diagnostics Cobas e411 system) for predicting -PE in a group of 67 high-risk pregnant women (20–37 gestation weeks).

Results

Among the 67 patients included, 53 had a sFlt-1/PlGF ratio lower than 38; none developed subsequent PE leading to a negative predictive value of 100%. Eight patients developed clinical PE. The positive predictive value was 21% at one week and 18% at four weeks, in accordance with previous studies.

Conclusions

The serum sFlt-1/PlGF ratio showed highly predictive performances for ruling out PE. Using these biomarkers in routine management of PE may improve clinical care and avoid inappropriate hospitalization, which has a significant economic impact.

Phenotypes of Pregnant Women Who Subsequently Develop Hypertension in Pregnancy

BACKGROUND

Hypertensive disorders complicating pregnancy are a major cause of maternal death. Our objective was to evaluate maternal clinical, hemodynamic, and placental prognostic indicators in a consolidated manner to identify women who develop hypertension in pregnancy.

METHODS AND RESULTS

Twenty-six normotensive pregnant women from a specialized Placenta Clinic at increased risk of developing de novo hypertension and 20 normotensive healthy pregnant controls were recruited at 22 to 26 weeks' gestation. Fourteen maternal clinical, hemodynamic, and placental characteristics were assessed in the second trimester and aggregated. Principal component analysis of this combined data set determined that 3 dimensions accounted for 56% of the cohort variability. The first dimension accounted for 31% of the cohort variability, with significant contributions from total peripheral resistance, endoglin, and cardiac output. The second dimension was predominantly influenced by body mass index and mean arterial pressure, while uric acid and myeloperoxidase mainly contributed to the third dimension. Unsupervised clustering identified 3 groups within this combined data set. Total peripheral resistance was the most significant distinguishing parameter between these groups (P<0.0001), followed by placental growth factor, endoglin, and cardiac output (P<0.0001). Using these 4 parameters, a receiver operating curve was constructed with an area under the curve of 0.975 (95% confidence interval 0.93-1) for the prediction of developing hypertension in pregnancy.

CONCLUSIONS

Consolidated assessment of prognostic indicators in the second trimester of pregnancy may be useful to characterize and distinguish pathways by which women may develop hypertension in pregnancy. This approach could contribute to the development of pathway-specific preventative and antihypertensive treatment strategies.

Angiogenic biomarkers in triage and risk for preeclampsia with severe features

There is an urgent need for biomarkers that can help stratify women with suspected preeclampsia (PE) for the subsequent appearance of PE with severe features (sPE), to improve risk assessment and direct monitoring related to complications of sPE. Elevated levels of circulating anti-angiogenic factors like soluble fms-like tyrosine kinase 1 (sFlt1) and decreased free levels of pro-angiogenic factors such as placental growth factor (PlGF) are associated with adverse outcomes related to preeclampsia (PE). Here, we report in a single-center prospective study (N = 402) that plasma levels of these circulating angiogenic markers predict sPE within two weeks among women presenting with suspected PE in the preterm period (<37 weeks). sFlt1/PlGF ratio of >38 at the triage visit had a positive predictive value (PPV) of 47% and a negative predictive value (NPV) of 98% for the presence of sPE within 2 weeks. Among patients presenting <34 weeks, the PPV for sPE improved to 65% with NPV of 98%. sFlt1/PlGF ratio >85, had a PPV of 59% in all patients and 74% among patients presenting <34 weeks for the presence of sPE within 2 weeks. When we restricted the analysis to hospitalized patients, PPVs were 58% and 63% in all patients and 73% and 77% for patients presenting <34 weeks for plasma sFlt1/PlGF cutoff >38 and >85 respectively. Clinical trials are needed to evaluate whether risk stratification with angiogenic biomarkers in patients with suspected PE will lead to improved maternal and fetal outcomes among women at risk for severe disease.

Recent advances in the diagnosis and management of pre-eclampsia

Pre-eclampsia is a leading cause of maternal mortality, responsible annually for over 60,000 maternal deaths around the globe. Pre-eclampsia is a multisystem disease featuring hypertension, proteinuria, and renal, hepatic, and neurological involvement. Diagnosis is often elusive, as clinical presentation is highly variable. Even those with severe disease can remain asymptomatic. Angiogenic factors are emerging as having a role in the diagnosis of pre-eclampsia and in prognostication of established disease. In this article, we summarize new developments and focus on angiogenic biomarkers for prediction of disease onset. We also discuss recent advances in management strategies for patients with hypertensive disorders of pregnancy.

Angiogenic and Antiangiogenic Markers for Prediction and Risk Classification of Preeclampsia

Preeclampsia is a pregnancy-specific hypertensive disorder with multisystem involvement and is a significant cause of obstetric morbidity and mortality worldwide. A major issue in the treatment of preeclampsia stems from its still significant rates of misclassification and misdiagnosis. Angiogenic factors have been speculated as a possible diagnostic modality due to a perceived imbalance in angiogenesis in preeclampsia. Factors currently studied include soluble fms-like protein kinase 1 and placental growth factor. Because of significant mortality associated with preeclampsia it is felt that both early and accurate diagnosis of preeclampsia is imperative if this disease process is to be treated.

Placental-specific sFLT-1: role in pre-eclamptic pathophysiology and its translational possibilities for clinical prediction and diagnosis

Pre-eclampsia is a common obstetric complication globally responsible for a significant burden of maternal and perinatal morbidity and mortality. Central to its pathophysiology is the anti-angiogenic protein, soluble fms-like tyrosine kinase-1 (sFLT-1). sFLT-1 is released from a range of tissues into the circulation, where it antagonizes the activity of vascular endothelial growth factor and placental growth factor leading to endothelial dysfunction. It is this widespread endothelial dysfunction that produces the clinical features of pre-eclampsia including hypertension and proteinuria. There are multiple splice variants of sFLT-1. One, known as sFLT-1 e15a, evolved quite recently and is only present in humans and higher order primates. This sFLT-1 variant is also the main sFLT-1 secreted from the placenta. Recent work has shown that sFLT-1 e15a is significantly elevated in the placenta and circulation of women with pre-eclampsia. It is also biologically active, capable of causing endothelial dysfunction and the end-organ dysfunction seen in pre-eclampsia. Indeed, the over-expression of sFLT-1 e15a in mice recapitulates the pre-eclamptic phenotype in pregnancy. Therefore, here we propose that sFLT-1 e15a may be the sFLT-1 variant primarily responsible for pre-eclampsia, a uniquely human disease. Furthermore, this placental-specific sFLT-1 variant provides promise for use as an accurate biomarker in the prediction or diagnosis of pre-eclampsia.

Angiogenic factors: potential to change clinical practice in pre-eclampsia?

Pre‐eclampsia is a complex disease with significant maternal and fetal morbidity and mortality. Its syndromic nature makes diagnosis and management difficult. The field is rapidly evolving with the definition of pre‐eclampsia being challenged by some organisations, with proteinuria no longer being essential in the presence of other features. In the last decade, angiogenic factors, in particular soluble fms‐like tyrosine kinase 1 (sFlt‐1), have emerged as important molecules in the pathogenesis of pre‐eclampsia. Here we review the most recent evidence regarding the potential of these factors as biomarkers and therapeutic targets for pre‐eclampsia.

Tweetable abstract

A review of angiogenic factors, sFlt‐1 and PlGF, in the diagnosis, prediction and management of pre‐eclampsia.

A review of angiogenic factors, sFlt‐1 and PlGF, in the diagnosis, prediction and management of pre‐eclampsia.

Angiogenic factors sFlt-1 and PlGF in preeclampsia: Prediction of risk and prognosis in a high-risk obstetric population

OBJECTIVES

Despite its simple definition, preeclampsia can have variable and atypical clinical presentations, an unpredictable course, and potential adverse maternal and fetal outcomes. No single test currently predicts risk or prognosis adequately. Scientific advances suggest that an angiogenic imbalance is involved in its pathophysiology. The objective of this study was to investigate the use of sFlt-1, PlGF, and their ratio in predicting preeclampsia.

MATERIALS AND METHODS

In a single-center prospective observational study, we measured the angiogenic markers sFlt-1 and PlGF and calculated the sFlt-1/PlGF ratio in patients at risk of preeclampsia at 20 to 37 weeks of gestation. The main outcomes were the occurrence of preeclampsia and the interval before its onset.

RESULTS

Of the 67 at risk patients included, 8 (12%) developed preeclampsia. For a sFlt-1/PlGF ratio ≥85, the specificity was 93%. The ratio was significantly higher (ratio=104±30) in women with an onset time less than 5 weeks than in those with later preeclampsia (ratio=10±2), P<0.001.

CONCLUSION

In a high-risk population, angiogenic markers appear to be an interesting aid in predicting the onset of preeclampsia with high specificity and in estimating time to onset. However, due to small number of cases of PE, more studies are needed before recommendations to use these markers in daily practice.

Efficacy of resveratrol to supplement oral nifedipine treatment in pregnancy-induced preeclampsia

OBJECTIVE

Preeclampsia (PE) is a complication affecting pregnant women worldwide, which usually manifests as severe maternal hypertension. Resveratrol (RESV), a naturally existing polyphenol, is known to exhibit beneficial effects in cardiovascular disease including hypertension. We evaluated the outcome of treatment combining oral nifedipine (NIFE) and RESV against PE.

DESIGN AND METHODS

Using a randomized group assignment, 400 PE patients were enrolled and received oral treatments of either NIFE + RESV or NIFE + placebo. Primary endpoints were defined as time to control blood pressure and time before a new hypertensive crisis. Secondary endpoints were defined as the number of doses needed to control blood pressure, maternal and neonatal adverse effects.

RESULTS

Compared with the NIFE + placebo group, the time needed to control blood pressure was significantly reduced in NIFE + RESV group, while time before a new hypertensive crisis was greatly delayed in NIFE + RESV group. The number of treatment doses needed to control blood pressure was also categorically lower in NIFE + RESV group. No differences in maternal or neonatal adverse effects were observed between the two treatment groups.

CONCLUSION

Our data support the potential of RESV as a safe and effective adjuvant of oral NIFE to attenuate hypertensive symptoms among PE patients.