Evaluation of agreement of placental growth factor (PlGF) tests and the soluble FMS-like tyrosine kinase 1 (sFlt-1)/PlGF ratio, comparison of predictive accuracy for pre-eclampsia, and relation to uterine artery Doppler and response to aspirin

Objectives: The objective of this study is to evaluate agreement between PlGF and sFlt-1/PlGF ratio tests and compare their predictive accuracy for pre-eclampsia in high-risk women. Also, to examine for associations of abnormal PlGF or sFlt-1/PlGF ratio with abnormal uterine artery Doppler and platelet response to aspirin. Methods: Prospective cohort study, 150 pregnant women at high risk of pre-eclampsia prescribed 75 mg aspirin daily. Uterine artery Dopplers were assessed at 20(+0)-23(+6) weeks. At 33(+0)-35(+6) weeks platelet function aspirin metabolites, PlGF and the sFlt-1/PlGF ratio were measured. Outcome: Measures were all pre-eclampsia and pre-eclampsia requiring delivery prior to 37 weeks. Results: Overall percent agreement was 89.3% for PlGF tests but 74.7-78% for PlGF tests and the sFlt-1/PlGF ratio. AUCs were 0.70-0.75 for prediction of any pre-eclampsia and 0.92-0.99 for preterm pre-eclampsia. We found a significant association between abnormal PlGF or sFlt-1/PlGF ratio and abnormal uterine artery Doppler (chi(2) 5.47, p = .019), but no association with platelet response to aspirin (chi(2) 0.12, p = .913). There were no associations between suboptimal aspirin adherence and either abnormal angiogenic markers or uterine artery Dopplers (chi(2) 0.144, 0.038, p = .704, .846, respectively). Conclusions: There was good agreement between PlGF tests and limited agreement between PlGF tests and the sFlt-1/PlGF ratio. All tests have heightened predictive accuracy for preterm pre-eclampsia. Abnormal PlGF or sFlt-1/PlGF ratio relates to abnormal uterine artery Doppler but not platelet response to aspirin.