06 Jan Elecsys® immunoassay Helps Predict Preeclampsia in Suspected Pregnancies
MedicalResearch.com Interview with:
Stefan Verlohren, MD, PhD
Consultant and Senior Lecturer
Klinik für Geburtsmedizin / Department of Obstetrics
Charité Campus Mitte
Medical Research: What is the background for this study? What are the main findings?
Dr. Verlohren: Preeclampsia affects 2–5% of pregnancies worldwide, and is a potentially life threatening syndrome for both mother and child. Treatment options for preeclampsia are very limited, with delivery being the only ‘cure’; however, early detection and monitoring are beneficial for improving maternal and fetal outcomes. Development of preeclampsia is very difficult to predict: its clinical presentation is variable and its signs and symptoms overlap with other conditions. There has been an unmet medical need for improved prediction of preeclampsia, i.e. predicting which women will develop preeclampsia and which will not. Women with suspected preeclampsia are often hospitalized until preeclampsia and related adverse outcomes are ruled out. Others who require hospitalization may be overlooked because their symptoms were nonspecific (e.g. headache).
Preeclampsia has been linked with impaired function of the placenta. Placental development is highly dependent on blood vessel formation; before and during preeclampsia, levels of molecules involved in blood vessel inhibition or growth are altered in the maternal bloodstream. In particular, soluble fms-like tyrosine kinase-1 (sFlt-1) (a molecule that inhibits blood vessel growth) is increased and placental growth factor (PlGF) (a molecule that encourages blood vessel growth) is decreased. This study has established that the ratio of these two molecules (sFlt-1:PlGF) can be used to predict whether preeclampsia will develop or not.
The sFlt-1:PlGF ratio can be calculated with a blood test (the Elecsys® sFlt-1 immunoassay and Elecsys® PlGF immunoassay). PROGNOSIS has validated the sFlt-1:PlGF ratio cutoff level of 38 for prediction of preeclampsia. For women with suspected preeclampsia, the Elecsys® immunoassay sFlt-1:PlGF ratio of 38 or below has a high negative predictive value to rule out preeclampsia or adverse fetal outcomes in the next week. A Elecsys® immunoassay sFlt-1:PlGF ratio of more than 38 indicates that preeclampsia or fetal adverse outcomes may develop in the next four weeks. In conjunction with other diagnostic and clinical information, the Elecsys® immunoassay sFlt-1:PlGF ratio can be used to guide patient management.
Medical Research: What should clinicians and patients take away from your report?
Dr. Verlohren: For Clinicians:
The Elecsys® immunoassay sFlt-1:PlGF ratio can be used, in conjunction with other diagnostic and clinical information, to predict the likelihood of a woman with suspected preeclampsia (after 24 weeks gestation) going on to develop preeclampsia, HELLP syndrome or adverse fetal outcomes. In cases of suspected (but not confirmed) preeclampsia, an Elecsys® immunoassay sFlt-1:PlGF ratio of 38 or below can provide additional confidence that a women is unlikely to develop preeclampsia in the following week; monitoring and management can therefore be adapted accordingly. When a woman with suspected (not confirmed) preeclampsia has an Elecsys® immunoassay sFlt-1:PlGF of more than 38, this should prompt consideration of more intensive monitoring, and, depending on the overall clinical assessment, potential specialist referral and/or hospitalization. The Elecsys® immunoassay sFlt-1:PlGF ratio is not a ‘standalone test’ but should be considered as an additional tool for aiding decision making in cases of suspected preeclampsia.
Preeclampsia may develop rapidly and can be dangerous for a pregnant woman and her baby. Once preeclampsia develops, patients need to be intensively monitored and may require early delivery. Unfortunately, preeclampsia is variable in its sign and symptoms, and so it is very difficult for physicians to make an accurate estimation of whether a woman is likely to develop preeclampsia, even if she has one or more symptoms. Women with symptoms and/or signs suggestive of preeclampsia are often hospitalized until preeclampsia and related adverse outcomes are ruled out.
The Elecsys® immunoassay sFlt-1:PlGF ratio is a blood test for women with suspected preeclampsia in the later stages of pregnancy (after 24 weeks), the results of which can help physicians better decide the risk of that woman going on to develop preeclampsia in the next week or month. A low value means that the woman is unlikely to develop preeclampsia in the next week; she will be monitored further but may not require hospitalization. A high value means that the woman may go on to develop preeclampsia with the next 4 weeks; the physician may decide to increase monitoring of mother and fetus and may decide to hospitalize the patient.
In summary, the Elecsys® immunoassay sFlt-1:PlGF ratio can be used to aid physicians to predict which women will not develop preeclampsia (and avoid unnecessary hospitalization for these women) and which women will potentially develop preeclampsia (so they can be monitored and managed appropriately).
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Verlohren: Future research should seek to understand how acting on knowledge of the sFlt-1:PlGF to rule out preeclampsia within one week influences outcomes for mothers and babies. A prospective, randomized study (INSPIRE: Interventional study evaluating the short-term prediction of preeclampsia/eclampsia in pregnant women with suspected preeclampsia) is underway at Oxford University Hospitals NHS Trust. INSPIRE will determine whether the Elecsys® immunoassay sFlt-1:PlGF ratio with a cutoff of 38 will reduce unnecessary admissions and investigations for patients with suspected preeclampsia by ruling out preeclampsia within one week.
Further analysis of the PROGNOSIS dataset will seek to understand the potential economic implications of the use of the Elecsys® immunoassay sFlt-1:PlGF ratio in clinical practice.
Harald Zeisler, M.D., Elisa Llurba, M.D., Ph.D., Frederic Chantraine, M.D., Ph.D., Manu Vatish, M.B., Ch.B., D.Phil., Anne Cathrine Staff, M.D., Ph.D., Maria Sennström, M.D., Ph.D., Matts Olovsson, M.D., Ph.D., Shaun P. Brennecke, M.B., B.S., D.Phil., Holger Stepan, M.D., Deirdre Allegranza, B.A., Peter Dilba, M.Sc., Maria Schoedl, Ph.D., Martin Hund, Ph.D., and Stefan Verlohren, M.D., Ph.D.
Stefan Verlohren, MD, PhD (2016). Elecsys® immunoassay Helps Predict Preeclampsia in Suspected Pregnancies