Rule-in and rule-out of pre-eclampsia using a novel point-of-care placental growth factor test

Abstract

Objective: To evaluate test performance of the point-of-care Lepzi® Quanti placental growth factor (PlGF) test to rule-in and rule-out pre-eclampsia at various time points, in women presenting with suspected preeclampsia. Study design: 242 frozen plasma samples from women with suspected pre-eclampsia were analysed from a prospective cohort study. Participants were recruited from two obstetric tertiary referral centres in London. Main outcome measures: PlGF concentration was quantified using the Lepzi® Quanti PlGF test, which is a point-of-care PlGF test. Test performance for diagnosis of pre-eclampsia was evaluated at various thresholds, and at different gestations. The area under the receiver operator curve (AUROC) was determined for the Lepzi® Quanti PlGF test and compared to that of the nationally recommended Delfia® Xpress PlGF1-2–3 test, in the same cohort of participants. Results: The LEPZI® Quanti PlGF test showed high test performance for rule-out of pre-eclampsia within seven and 28 days. A threshold of ≥ 129 pg/ml (in plasma) had high negative predictive value (NPV) for rule out of preeclampsia within seven days of sampling: NPV 96.9 % at < 34 weeks’ gestation (95 % confidence interval (CI) 91.2–99.4), NPV 97.0 %; at 34 – 37 weeks’ gestation (95 % CI 84.2–99.9), NPV 80.0 % at ≥ 37 weeks gestation (95 % CI 44.4–97.5). Conclusion: The LEPZI® Quanti PlGF test demonstrates high test performance for diagnosis of pre-eclampsia, comparable to test performance for validated, nationally recommended PlGF tests. The LEPZI® Quanti PlGF test is a whole blood, point-of-care option to optimise risk stratification, enhanced surveillance, and appropriate management strategies; this would be suitable for low- and middle-income settings, as well as high-income settings.