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Bringing clarity to preeclampsia risk assessment
The PreClara™ Ratio (sFlt-1/PlGF) is the first FDA-cleared biomarker test for preeclampsia, offering clarity in assessing the risk of developing preeclampsia with severe features in hospitalized pregnant women within two weeks of testing.1 The test should be used in conjunction with other laboratory tests and standard clinical assessment.
The PreClara Ratio, derived from patient serum or plasma and run on the B·R·A·H·M·S KRYPTOR immunoassay analyzer, measures two placental biomarkers which are linked to the development of preeclampsia: soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF).2
Key clinical benefits
May improve clinical decision making regarding:
- Stepped up care and surveillance
- Transfer to tertiary care center
- Resource allocation and cost optimization
- Patient and family counseling3,4
Intended use
The PreClara Ratio (sFlt-1/PlGF) is to be used in conjunction with other laboratory tests and clinical assessments to aid in the risk assessment of pregnant women (singleton pregnancies between 23+0 and 34+6/7 weeks gestation) hospitalized for hypertensive disorders of pregnancy (preeclampsia, chronic hypertension with or without superimposed preeclampsia, or gestational hypertension) for progression to preeclampsia with severe features* within two weeks of presentation.1
The PreClara Ratio must be calculated using the B·R·A·H·M·S sFlt-1 KRYPTOR and the B·R·A·H·M·S PlGF plus KRYPTOR results measured on the B·R·A·H·M·S KRYPTOR analyzer.
Clinical cut-off and test interpretation
If the result of the ratio is lower than 40, pregnant woman is at low risk for progression to preeclampsia with severe features within two weeks.
Follow standard of care including expectant management.*
If the result of the ratio is higher or equal to 40, pregnant woman is at high risk for progression to preeclampsia with severe features within two weeks.
Consider stepped up care and intensify surveillance before preeclampsia with severe features develop.*1
Clinically validated results – PRAECIS clinical study
The PRAECIS (Preeclampsia Risk Assessment: Evaluation of cut-offs to Improve Stratification) study is the largest prospective US study to date and included 30% Black and 16% Hispanic women. The PRAECIS study clearly demonstrated that in women hospitalized with a hypertensive disorder of pregnancy presenting between 23 and 35 weeks of gestation, measurement of serum sFlt-1/PlGF provided stratification of the risk of progressing to severe preeclampsia (sPE) within two weeks of presentation as well as a strong association with adverse outcomes.2
Clinical performance of sFlt-1/PlGF at cut-off of 40 to predict preeclampsia with severe features.2
- 65% PPV (95% CI, 59 to 71)
- 96% NPV (95% CI, 93 to 98)
- 94% Sensitivity (95% CI, 89 to 96)
- 75% Specificity (95% CI, 70 to 79)
The PreClara Ratio performed better than standard clinical measures (area under the ROC, 0.92 versus 0.75).
| Predicting maternal and fetal adverse outcomes | |
|---|---|
| 40x | Women who developed preeclampsia with severe features had sFlt-1/PIGF ratios approximately 40 times higher than those who did not.2 |
| 10x | The sFlt-1/PIGF ratio was approximately 10 times higher for women who developed adverse maternal outcomes than for patients who did not.2 |
| 30x | The sFlt-1/PIGF ratio was approximately 30 times higher in women with an adverse fetal and neonatal outcome compared with those without.2 |
| 40 | Women with an sFlt-1/PIGF ratio ≥ 40 were more likely to deliver (spontaneously or induced) within 2 weeks compared with women with a ratio <40.2 |
Implications for clinical practice2
The measurement of sFlt-1/PIGF can be used to determine if patients require stepped up care or if expectant management per ACOG guidelines should be followed.1
Guidance from the American College of Obstetricians and Gynecologists
The American College of Obstetricians and Gynecologists (ACOG) advises that “If the sFlt-1:PlGF ratio is used for hospitalized patients admitted between 23 and 35 weeks of gestation with hypertensive disorders, the test is a complementary risk stratification screen to add to the diagnostic work-up of preeclampsia with severe features.”6
Related stories on preeclampsia
References
*As defined by the American College of Obstetrics and Gynecology (ACOG)5
- US IFU PreClara Ratio (sFlt-1/PlGF)
- Thadhani, et al. Circulating angiogenic factor levels in hypertensive disorders of pregnancy. NEJM Evid 2022;1:EVIDoa2200161.
- Khosla, et al. Cost effectiveness of the sFlt1/PlGF ratio test as an adjunct to the current practice of evaluating suspected preeclampsia in the United States, Pregn Hyperten 2021; 26:121-126.
- Burns LP, Potchileev S...Rana S. Real-World Evidence for Utility of Serum sFlt-1/PlGF Test for Routine Clinical Evaluation of Hospitalized Women with Hypertensive Disorders of Pregnancy. Am J Obstet Gynecol. 2024 Jul 17:S0002-9378(24)00758-0. PMID: 39029547.
- Gestational Hypertension and Preeclampsia: ACOG Practice Bulletin Summary, Number 222. Obstetrics and Gynecology. 2020;135(6):1492-1495.
- ACOG Clinical Practice Update: Biomarker Prediction of Preeclampsia With Severe Features. Obstetrics & Gynecology. June 2024;143(6):p e153-e154.
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