Studies Show Single PIGF Marker Tests Effective to Aid in Diagnosing Preeclampsia

While dual biomarker tests are more established, additional evidence is now confirming that PIGF as a stand-alone marker could be as effective as the established sFlt-1/PlGF ratio for managing preeclampsia.

Placental growth factor (PlGF) is an angiogenic protein synthesized by the placenta. A low concentration has been strongly correlated with preeclampsia. There is proof that a placental growth factor test can provide an alternative to dual biomarker testing to aid in the diagnosis of preeclampsia.

Several companies manufacture PlGF‐based tests that can be used in clinical practice to assist in ruling out a diagnosis of pre‐eclampsia in women presenting with suspected preterm pre‐eclampsia. These include the DELFIA Xpress PlGF 1‐2‐3 test (PerkinElmer), Triage PlGF test (Quidel), the Kryptor sFlt-1/PlGF ratio (Brahms), and the Elecsys immunoassay sFlt‐1/PlGF ratio (Roche Diagnostics). The Triage PlGF test and the Elecsys immunoassay sFlt‐1/PlGF ratio, used with standard clinical assessment and subsequent clinical follow‐up, are currently recommended by NICE UK for this purpose. The Guidelines are currently being reviewed, and an updated Guideline is expected to be published in July 2022.These tests measure PlGF alone (Triage PlGF) and sFlt-1/PlGF ratio (Elecsys).

Results of a study conducted in Women’s Health Academic Centre, St Thomas’ Hospital, King’s College London, United Kingdom were published in Obstetrics and Gynaecology and in Pregnancy Hypertension by F.P. McCarthy, et. al and Giblin et al, respectively. The study compared three commercially available placental growth factor-based tests. This analysis covered samples of women with suspected preterm preeclampsia before 35 weeks gestation, comparing the three tests’ ability to predict delivery within 14 days from testing.

The findings of these studies showed that the DELFIA® Xpress PlGF 1-2-3 test is equivalent to other tests already proven to work as a rule-out test for preeclampsia. These papers also showed that these tests are suitable and equivalent as rule-in tests. However, it was determined that further studies were needed.

To that end, a study published in March 2022 in Pregnancy Hypertension further proved that testing for low PlGF markers alone could provide a low-cost (and simpler) alternative to dual biomarker testing.

The four goals of this study were:

• To validate rule-in (<50 pg/ml) and rule-out (≥150 pg/ml) thresholds for DELFIA® Xpress PlGF 1-2-3 test to predict preeclampsia
• To establish sFlt-1/PlGF ratio thresholds for rule-in and rule-out of preeclampsia within seven and 28 days using DELFIA Xpress sFlt-1 and PlGF 1-2-3 assays
• To compare test performance between low PlGF concentrations and sFlt-1/PlGF ratio in a group of women with suspected preeclampsia;
• To assess PlGF 1-2-3 test concentration and sFlt-1/PlGF ratio threshold performance to confirm a diagnosis of preeclampsia using a group of women with confirmed preeclampsia compared to those without

The findings concluded:

• DELFIA Xpress PlGF1-2-3 thresholds can be used to rule-in (<50 pg/ml) and rule-out ≥ 150 pg/ml) preeclampsia. This suggests that PlGF testing alone may offer a reasonable and more cost-effective alternative than sFlt-1/PlGF ratio for ruling out early preeclampsia
• There are no statistical differences in overall performance between low PlGF concentrations and sFlt-1/PlGF ratio to identify women diagnosed with preeclampsia within seven and 28 days
• Performance of both low PlGF concentrations and sFlt-1/PlGF ratios were significantly reduced in women with Chronic Kidney Disease(CKD), but other risk factors for preeclampsia were not associated with lower performance

Evidence that PIGF marker tests alone provide equal performance for preeclampsia management and could provide a cheaper alternative to dual biomarker testing.

Rule-in and rule-out of pre-eclampsia using DELFIA Xpress PlGF 1-2-3 and sFlt-1: PlGF ratio / https://doi.org/10.1016/j.preghy.2021.12.008

Conclusion: There may be another choice.

If your lab is already using sFlt-1/PlGF ratio dual biomarkers for testing, you may want to continue with the same approach, but those not yet using biomarkers for PE management might want to explore the possibilities available with the new single marker PIGF test.

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