1.1 The following placental growth factor (PLGF)-based tests, used with standard clinical assessment, are recommended to help decide on care (to help rule in or rule out pre-eclampsia) for people with suspected preterm (between 20 weeks and 36 weeks and 6 days of pregnancy) pre‑eclampsia:
DELFIA Xpress sFlt‑1/PLGF 1‑2‑3 ratio
Elecsys immunoassay sFlt‑1/PLGF ratio
Triage PLGF Test.
Not all manufacturers indicate their tests for use across the full range of 20 weeks to 36 weeks and 6 days of pregnancy. The tests should be used according to their indications for use (see section 2).
1.2 PLGF-based testing may particularly benefit groups at higher risk of severe adverse pregnancy outcomes, such as people from African, Caribbean and Asian family backgrounds.
1.3 Further research is recommended into how well the tests work when people are pregnant with more than 1 baby (see section 4.3).
1.4 Do not use PLGF-based tests to make decisions about whether to offer a planned early birth to people with preterm pre-eclampsia. The NICE guideline on hypertension in pregnancy has recommendations on timing of birth.
1.5 Use a PLGF-based test once per episode of suspected preterm pre‑eclampsia. Further research is recommended on repeat testing (see section 4.2).
1.6 BRAHMS sFlt‑1 Kryptor/BRAHMS PLGF plus Kryptor PE ratio is not recommended for routine use in the NHS. Further research is needed to show the accuracy of this test when using specified thresholds (see section 4.1).
Why the committee made these recommendations
The DELFIA Xpress PLGF 1‑2‑3 test was not previously recommended by NICE because there was not enough evidence on its accuracy. High-quality evidence now shows that this test, and the DELFIA Xpress sFlt‑1/PLGF 1‑2‑3 ratio assay, have good accuracy for preterm pre-eclampsia.
NICE previously recommended the Elecsys immunoassay sFlt‑1/PLGF ratio and Triage PLGF Test to help rule out pre-eclampsia. But they were not recommended to help diagnose (rule in) pre-eclampsia because of concerns that this could result in people being unnecessarily offered early births. Data now shows that this is not the case.
Modelling shows that all these tests are cost effective compared with standard assessment when used to help diagnose (rule in) or exclude (rule out) preterm pre‑eclampsia. So these tests are recommended to help plan safe care and a safe birth for people with pre-eclampsia, and also to identify people unlikely to develop pre-eclampsia, and therefore reduce unnecessary hospitalisation. The tests may work differently in people who are pregnant with more than one baby. Therefore, NICE has recommended further research to find out how well the tests work in this group.
There is not enough evidence on whether or not the test should be repeated. Therefore, NICE has recommended testing just once when a person presents with possible symptoms of preterm pre-eclampsia (an episode) and recommended further research on if repeat testing improves outcomes.
There is new data for BRAHMS sFlt‑1 Kryptor/BRAHMS PLGF plus Kryptor PE ratio, which was originally not recommended. But the data is lower quality than that for the other tests. Data on test sensitivity and specificity is from 2 studies, 1 that was small and 1 that did not specify the test threshold to use in advance. There is not enough good-quality data to assess how well it works and its cost effectiveness. There is also uncertainty about how the company intends the test to be used. So this test is still not recommended.