Obstetricians and midwives are today welcoming the publication of new NICE guidance recommending the use of a new test from Roche Diagnostics that can rule-out the development of the life threatening condition, pre-eclampsia, within one week in pregnant women.
Hypertensive disorders, like pre-eclampsia, currently affect approximately 13.5 per cent of pregnancies in the UK. It is estimated that as many as 80,000 pregnant women are investigated for suspected pre-eclampsia each year, and the introduction of the test could reduce hospitalisation by 50%. NICE estimates that the cost reduction per patient of using the sFlt-1/PlGF ratio test rather than standard clinical assessment to rule out pre-eclampsia before 35 weeks is £2,488 in England and Wales. Annual UK savings are projected to be >£16 million.
Previous treatment guidelines have recommended that all women presenting with hypertension and proteinuria are admitted to hospital for monitoring, although most would not go on to develop pre-eclampsia. This unnecessary hospitalisation causes undue stress and anxiety for mothers, as well as significant costs to hospitals and the NHS. In-patient monitoring of potentially pre-eclamptic patients requires additional capacity, clinical hours and staff care, placing additional pressures on an already stretched NHS.
The new assay from Roche Diagnostics allows healthcare professionals to conduct a simple blood test, to determine whether an individual patient will develop pre-eclampsia over the next week. With 99.3 per cent accuracy, women deemed not at risk could safely return to community care, instead of being admitted to hospital for further observations.
Within the updated guidance, clinicians and midwives are now advised to use the Elecsys immunoassay sFlt-1/PlGF ratio to measure the levels of placental growth factor (PlGF) in the blood. PlGF is a protein involved in the development of new blood vessels in the placenta, and in pre-eclampsia, levels of PlGF can be abnormally low. The ratio also measures soluble FMS-like tyrosine kinase-1 (sFlt-1), a protein which is thought to disable proteins associated with blood vessel formation, such as PlGF. In women who develop pre-eclampsia, the levels of sFlt-1 have been shown to be higher than those seen in normal pregnancy. The sFlt-1/PlGF ratio has shown better diagnostic ability compared to either biomarker alone.
The NICE consultation drew on evidence from the PROGNOSIS study published in the New England Journal for Medicine, which evaluated the use of Elecsys® sFlt-1/PlGF ratio for short-term prediction of pre-eclampsia/eclampsia/HELLP syndrome in 1,273 pregnant women with suspected pre-eclampsia.
The study found that the ratio test could exclude pre-eclampsia for one week with a negative predictive value (NPV) of 99.3%. (95% confidence interval [CI], 97.9-99.9) with 80.0% sensitivity and 78.3% specificity. To rule in pre-eclampsia within 4 weeks, the positive predictive value (PPV) was 36.7% (95% CI, 28.4-45.7), with 66.2% sensitivity and 83.1% specificity.
Dr Manu Vatish, Consultant Obstetrician at John Radcliffe, Oxford University Hospital, said:
Pre-eclampsia affects around three per cent of all pregnancies, but symptoms are often non-specific and, without a reliable test to diagnose the condition, many women are admitted to hospital unnecessarily. Not only does this result in additional stress for the women involved, but it also places pressure on the NHS through unnecessary tests and extra inpatient bed days.
The new guidance shows that a new era has arrived in the management of this disease. The research demonstrates that the new test from Roche Diagnostics, which can give a result in 18 minutes, is exceptionally good at ruling out the presence of the disease and is intended to be used alongside clinical judgement. Effectively ruling out the disease means reducing unnecessary admissions. Allowing women who are not at risk to go home safely means that the NHS can focus attention on women who have the greatest need.
Linda Holden and Georgina Longley, Midwives at John Radcliffe, Oxford University Hospital, commented:
Although not every patient presenting with suspected pre-eclampsia will go on to develop the condition, it’s very important to take each case seriously. There is significant unmet need within hypertensive disorders, and this new guidance certainly takes a step towards addressing this. The new test could provide peace of mind for many parents and potentially relieve pressure on the wards and among the antenatal staff.