Saturday, May 28, 2016

Two blood tests to rule out pre-eclampsia approved by The National Institute for Health and Care Excellence (NICE), UK.

According to an estimate by NHS mild pre-eclampsia affects up to 6% of pregnancies, while 1-2% of patients develop severe preeclampsia.  Data Centre for Maternal and Child Enquiries Mission statement shows pre-eclampsia, and associated eclampsia, are the second leading cause of direct maternal deaths in the UK.

NICE have approved and recommended two blood tests Triage PlGF test (Alere) and the Elecsys immunoassay sFlt-1/PlGF ratio (Roche Diagnostics) to help rule-out pre-eclampsia between 20th and 35th week of pregnancy.

The tests detect changes in the blood indicating that the placenta is not developing properly.
The tests however are not meant for diagnosing preeclampsia.

The tests were approved by NICE after the groundbreaking PROGNOSIS study results were published in New England Journal of Medicine in January,2016. 

The PROGNOSIS study has demonstrated that low ratios of the proteins sFlt-1 and PlGF in the blood of women at high risk of developing of preeclampsia can predict the absence of the condition within a period of one week (the rule-out claim). The data published today show that an sFlt-1/PlGF ratio of 38 and below can rule out the development of preeclampsia within the next week with a very high confidence level of 99.3%.

PROGNOSIS was a multi-center, prospective, double-blind, non-interventional trial evaluating the short-term prediction of preeclampsia, eclampsia and HELLP (hemolysis, elevated liver enzymes, low platelet count) syndrome in pregnant women with suspected preeclampsia. Sponsored by Roche, the PROGNOSIS study aimed to address the limitations of the traditional clinical parameters used to predict preeclampsia, and to demonstrate the utility of the Elecsys® preeclampsia ratio test in this context.

Identifying women who are unlikely to develop preeclampsia in the short term will save them from the stress of monitoring and the disruption to their home life caused by a stay in hospital.

The test is available in all countries accepting the CE mark in Europe, Latin America, Middle East, Africa and Asia. The test is currently not available in the United States and Japan.

PROGNOSIS also demonstrated that an sFlt-1/PlGF ratio greater than 38 may help predict whether women with suspected preeclampsia will develop the condition within four weeks (the rule-in claim), allowing doctors to identify at-risk patients who need close monitoring.


Dr Jenny Myers, who is also Senior Lecturer and Consultant Obstetrician, Maternal and Fetal Health Research Centre, Central Manchester Foundation Trust said “At the moment women with suspected pre-eclampsia often have to come into hospital for 24 to 36 hours so we can make a diagnosis, but now, for women between 20th and 35th week of their pregnancy, these new tests may avoid the need for admission to hospital.”

“The tests will be extremely valuable to help rule out pre-eclampsia before the 35th week of pregnancy, when approximately 1/3 of women with pre-eclampsia are diagnosed.

“Doctors will need to be clear with patients, depending on which test is used, the result is only valid for 7 to 14 days and neither test definitively rules out pre-eclampsia for the rest of the pregnancy.
“However these tests represent a great stride forward in the management and treatment of pre-eclampsia.”

The cause of preeclampsia is not fully understood; many factors have been implicated in the development of this life threatening disease. Recent research provides evidence that angiogenic factors such as placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) play a major role in the development of the disease.

It is postulated that preeclampsia is caused by an imbalance of angiogenic factors of sFlt-1 (anti-angiogenic protein) and PlGF (pro-angiogenic protein). During normal pregnancy both these proteins are involved in placental vascular remodeling.

In normal pregnancy, PlGF levels rise and peak at 26 to 30 weeks, so when PlGF levels do not rise during pregnancy this may be an indicator that the placenta is not developing properly, predict subsequent development of preeclampsia.

The Elecsys immunoassay sFlt-1/PlGF ratio also measures a protein called soluble FMS-like tyrosine kinase-1 (sFlt-1). The protein sFlt-1 stops other proteins that help to form blood vessels, like PlGF, from working. In pre-eclampsia if sFlt-1levels are higher than those seen in normal pregnancy it could be an indicator the placenta is not developing properly.

The sFlt-1/PlGF ratio measurement in combination with proteinuria, blood pressure and Doppler ultrasound gives better prediction of preeclampsia.

Professor Carole Longson, director of Centre for Health Technology at NICE added “Until now there have been no tests which doctors can use to confidently rule-out pre-eclampsia. This has meant women with suspected pre-eclampsia often need increased monitoring or have to stay in hospital. Apart from being inconvenient, this can increase anxiety at what might already be a stressful time.

“In recommending these tests the committee highlighted the importance of making sure laboratories explain to clinicians if a test result doesn’t rule-out pre-eclampsia they should not automatically diagnose women with pre-eclampsia.

Instead doctors should follow existing NICE guidelines to make such a diagnosis. This is so that babies aren’t delivered unnecessarily early as a result of these tests.”

Two other tests were also considered initially but later not included in the guidelines.

NICE recommends further research and trials to be carried out using these tests in women with suspected preeclampsia.

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