Elecsys® sFlt-1/PlGF ratio for preeclampsia

Objective results. Accurate risk prediction. Delivered with speed.

What is preeclampsia?

Preeclampsia is a serious multi-system pregnancy complication that can have devastating and lasting impacts on mothers and babies. It remains one of the leading causes of maternal and perinatal morbidity and mortality worldwide.¹

Characterized by high blood pressure and signs of damage to organ systems, most often the liver and kidneys, preeclampsia typically develops after 20 weeks of pregnancy. The clinical presentation of preeclampsia and the subsequent clinical course of the disorder can vary tremendously, making prediction, diagnosis and assessment of progression difficult.²

Each year in the U.S., there are 4 million pregnancies, of which 3% to 4% are affected by preeclampsia. From 2017-2019, hypertensive disorders of pregnancy — including gestational hypertension, chronic hypertension, preeclampsia and superimposed preeclampsia — accounted for 6.3% of pregnancy-related deaths in the U.S.³

Black women experience higher rates of maternal and infant morbidity and perinatal mortality than other racial and ethnic groups and are at greater risk for developing hypertensive disorders of pregnancy than other pregnant women.⁴ Learn more about the impact of preeclampsia by hearing Chaniece’s story.

Short-term prediction of preeclampsia management

The Elecsys® sFlt-1/PlGF ratio is an FDA-cleared test that provides objective data to complement standard clinical assessment and laboratory evaluation in risk stratification for preeclampsia with severe features.⁵ This prognostic tool is particularly valuable given that conventional indicators of preeclampsia often lack specificity and may not accurately predict disease severity or short-term adverse outcomes.¹

Close monitoring for severe features among high-risk patients is essential for guiding clinical management decisions, including the need for hospitalization, therapeutic interventions and timely delivery to prevent both fetal mortality and maternal morbidity.⁶

The Elecsys® sFlt-1/PlGF ratio is an FDA-cleared test offering a fast and reliable way to aid in assessing risk for preeclampsia with severe features in hospitalized patients within two weeks of testing.⁵ The preeclampsia ratio should be used in conjunction with standard clinical practice clinical assessment and routine laboratory testing. Identification of high-risk patients can lead to better monitoring, earlier interventions and reduced adverse outcomes for mothers and fetuses.⁶

Short-term prediction of preeclampsia

Preeclampsia is defined as the new onset of hypertension and proteinuria after 20 weeks of gestation and can be treated only by removal of the placenta.² The clinical presentation of preeclampsia and the subsequent clinical course of the disorder can vary tremendously, making prediction, diagnosis and assessment of progression difficult.²Typical indicators of preeclampsia progression, including proteinuria and hypertension, are poor in predicting disease progression, with a positive predictive value of 18% to 20%.⁷

sFlt-1 and PlGF are key biomarkers in the formation of blood vessels during pregnancy. However, an angiogenic imbalance of these key biomarkers has been proven to play an important role in the development of preeclampsia. Their concentrations in maternal serum are altered even before the onset of the disease, making them a valuable tool for predicting preeclampsia progression.^6,8,9,10

Key features of the Elecsys® sFlt-1/PlGF ratio for preeclampsia⁶

High negative predictive value to support clinical decision-making
Available on any cobas® e platform
Fast results using ready-to-use reagents in less than 18 minutes
Low sample volumes
- cobas® e 411 / e 601 / e 602: 20 µL (sFlt-1), 50 µL (PlGF)
- cobas® e 402 / cobas e 801: 20 µL (sFlt-1), 12 µL (PlGF)
Long reagent, calibration and sample stability
High tolerance to common interferants including biotin and hemoglobin
Wide measuring ranges
Precise results (<5% imprecision) with high reproducibility

Disclaimer

Key precautions for labs:

The ratio must be calculated using Elecsys sFlt‑1 and Elecsys PlGF results obtained on the same patient sample and the same cobas immunoassay analyzer. The assays are not intended to be used individually. Use of another manufacturer’s assays may result in significantly different ratios.
sFlt‑1 and PlGF values determined on patient samples using other manufacturers’ assays may result in significantly different ratios, which could lead to wrong diagnostic conclusions. Therefore, only the Elecsys sFlt‑1 and Elecsys PlGF assays should be used to calculate the Elecsys sFlt‑1/PIGF ratio.

Key clinical benefits^11,12

With the preeclampsia ratio as a complementary tool to aid in risk stratification, your practice may improve clinical decision-making regarding:

Increased surveillance and management
Discharge decisions

Referral to tertiary care centers
Hospital bed management and associated cost savings

Implications for clinical practice

This test can offer valuable clinical insights that can assist with:⁵

Stratification of risk into low and high risk of progression to preeclampsia with severe features
Appropriate patient management based on American College of Obstetricians and Gynecologists (ACOG) guidelines
Timely surveillance of the patient and appropriate delivery timing

Clinically validated results — PRAECIS study at Roche¹¹

The PRAECIS study at Roche was a prospective multicenter trial conducted across 18 US tertiary and community hospitals to validate the Elecsys® sFlt-1/PlGF ratio for preeclampsia for predicting preeclampsia with severe features. The study enrolled pregnant women ≥18 years old admitted to the hospital between 23+0 and 34+6/7 gestational weeks with singleton pregnancies and hypertensive disorders of pregnancy.

The primary outcome was the prediction of preeclampsia with severe features within two weeks of testing, compared against clinically adjudicated diagnoses made by maternal-fetal medicine experts blinded to local diagnoses and test results.

The Elecsys® sFlt-1/PlGF ratio for preeclampsia demonstrated superior performance when compared to the standard of care alone (AUC of 0.92 for sFlt-1/PlGF ratio versus 0.74 for standard tests).

Clinical performance at a cutoff of 38 as a predictor of preeclampsia with severe features using the preeclampsia ratio:

94.7% NPV (91.5-96.9%)
66.9% PPV (60.8-72.7%)
91.4% sensitivity (86.4-95.0%)
77.3% specificity: (72.7-81.5%)

The preeclampsia ratio is a strong predictor of preeclampsia with severe features, especially when compared to other standard-of-care measures today.

Guidelines from the American College of Obstetricians and Gynecologists on biomarkers for prediction of preeclampsia with severe features¹³

The American College of Obstetricians and Gynecologists (ACOG) advises that the sFlt-1/PlGF ratio can be helpful as an additional tool for assessing risk, but the test should not be used alone to diagnose or rule out severe preeclampsia. Instead, the sFlt-1/PlGF ratio should be viewed as one component of a comprehensive evaluation that includes clinical assessment and standard lab work.

Cost and risk avoidance associated with the sFlt-1/PlGF ratio

Preeclampsia represents a major economic burden on healthcare systems as a leading cause of maternal hospitalizations and iatrogenic delivery.¹⁴ The evaluation and management of preeclampsia requires intensive monitoring with repeated diagnostic testing and frequent use of emergency and inpatient services, while also being a significant contributor to NICU admissions and premature delivery.¹⁵

Implementation of the sFlt-1/PlGF ratio, in combination with standard clinical practice, could result in:

A significant reduction of women unnecessarily admitted for suspected preeclampsia¹²
A significant cost-savings arising from a reduction in admissions¹²
A larger proportion of women that could be discharged (67.8% versus 51.0%, p<0.0001)¹⁶