The PARROT-2 Trial
Research type
Research Study
Full title
Placental growth fActor Repeat sampling for Reduction of adverse perinatal Outcomes in women with suspecTed pre-eclampsia
IRAS ID
265824
Contact name
Lucy Chappell
Contact email
Sponsor organisation
King's College London
Duration of Study in the UK
2 years, 0 months, 1 days
Research summary
Research Summary
Pre-eclampsia is a condition, occurring only in pregnancy, thought to be caused by the placenta. Women with pre-eclampsia can suffer from high blood pressure, problems with their kidneys, liver and blood clotting. The problems with the placenta can mean that the baby’s growth is affected; in some cases the baby can be stillborn. Once diagnosed, the only cure is to deliver the baby. If pre-eclampsia occurs before 37 weeks of pregnancy, women may need to be admitted to hospital to have treatment and monitoring for complications, whilst planning for safe delivery of the baby. Some women become unwell very quickly and need to have their babies delivered; others have long stays in hospital. It can be difficult to identify women at high-risk of severe complications of pre-eclampsia.
We are planning a study to look at blood levels of proteins produced by the placenta, one of which is called Placenta Growth Factor (PlGF). Studies have shown that women with very low PlGF levels are at greater risk of severe pre-eclampsia and stillbirth. However, we don’t know how PlGF levels change over time. We plan to do a trial (a ‘fair test’ of a new treatment or intervention) to see if using repeated blood samples can help to reduce severe complications for babies, and for women. All participants be randomised to ‘revealed’ or ‘concealed’ repeat PlGF-based testing and have a maximum of 4 blood samples (taken with clinical bloods wherever possible). Follow up data will be collected and analysed to assess the impact of repeat PlGF-based sampling on mother and baby, in addition to the diagnostic accuracy and cost implications of these tests. The study will be conducted in at least 15 UK sites.
Lay summary of study results: 09 February 2024 (KCL)
Results from the PARROT-2 trial, published today in the Lancet by researchers from King’s College London and funded by Jon Moulton Charitable Trust, Tommy’s Charity and the National Institute for Health and Care Research, has ruled out the need for routine repeat placental growth factor-based testing (PIGF) for all women with suspected pre-eclampsia.
PARROT-2 is a large, multi-centre UK trial in 1,252 women with suspected preterm pre-eclampsia, a life-threatening condition for pregnant women, and their babies, that can lead to major complications, such as stillbirth and neonatal death, as well as longer hospital stays.
PIGF testing is a blood test that can detect levels of placental growth factor and soluble flt-1, which are biomarkers for pre-eclampsia. An abnormal result will identify those women and babies at higher risk of adverse outcomes, who need intensive surveillance, whilst a normal result means women can be safely discharged home to continue with normal antenatal care. Use of an initial test in pregnancy was rolled out across much of England in 2021.
The findings show that repeat testing enabled faster diagnosis of pre-eclampsia, but this did not translate into better outcomes for women or their babies.
Dr Alice Hurrell, first author of the study from the School of Life Course & Population Sciences, said: “This large trial has major implications for policy, practice, and guidelines. Universal, routine repeat testing, as recommended by some international groups, is not supported by our findings. However, the clinical benefit of a one-off placental growth factor-based test when pre-eclampsia is first suspected, remains clear.”
She added: "With an estimated 5% of all women affected by preterm hypertension in pregnancy (around 7 million pregnancies worldwide), this is now a pivotal time to ensure that placental growth factor-based testing can reach widespread implementation across healthcare settings.”
Professor Lucy Chappell, NIHR Senior Investigator and Chief Investigator for the PARROT-2 trial, said "Pregnant women repeatedly tell us the value of having greater certainty on diagnosis. These trial results should further lower the barriers to widespread equitable adoption of initial placental growth factor-based testing, improving maternal health outcomes globally."
Marcus Green, CEO of Action on Pre-eclampsia, said: “These are really important findings showing that once the first test has been done, there is nothing to be gained from further testing. A single test can assure women with certainty if they are likely or unlikely to get pre-eclampsia. We look forward to completion of roll-out of placental growth factor-based testing across England, with an urgent call for implementation in the devolved administrations across all four nations. These new results also provide a timely opportunity to tackle the higher burden of adverse outcomes due to pre-eclampsia in global settings.”
Kath Abrahams, Chief Executive of Tommy’s, said: “This important study funded by Tommy’s is a significant and positive step forwards in the drive to reduce the harm caused by pre-eclampsia.
“Following the breakthrough made by the previous Tommy’s funded PARROT study, we hope it will pave the way for PlGF testing for all women and birthing people who are thought to be at risk of pre-eclampsia, so that those most in need can be offered vital extra monitoring and support.”
URL to summary results: https://gbr01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fclick.pstmrk.it%2F3ts%2Fwww.isrctn.com%252FISRCTN85912420%253Fq%253Dparrot%2526filters%253D%2526sort%253D%2526offset%253D1%2526totalResults%253D4%2526page%253D1%2526pageSize%253D10%2526searchType%253Dbasic-search%2FNBTI%2F71W3AQ%2FAQ%2F5b2430e0-9129-4a7b-8439-04088bc400db%2F1%2FOEYb4fxZhJ&data=05%7C02%7Ccambridgeeast.rec%40hra.nhs.uk%7C30bd096e5d9442d51f7808dcbc77ba55%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C638592469613350311%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=l95yfDwoPcLlhsqa%2Ff2M4PjXau6FwH70iLONk0fOpK4%3D&reserved=0
REC name
East of England - Cambridge East Research Ethics Committee
REC reference
19/EE/0322
Date of REC Opinion
11 Nov 2019
REC opinion
Further Information Favourable Opinion