Background:
Preeclampsia (PE), which almost occurs on the basis of hypertension (≥140/90mmHg on 2 separate occasions of at least 4 hours apart) in pregnancy, affects 2-8% of pregnancies and constitutes one of the major causes of maternal and perinatal mortality globally[1]. In China, the rate of still birth in the women with PE and eclampsia increased 4-fold compared to normotensive pregnancies[2]. Early prediction of PE remains a challenge in clinical practice.
The pathogenesis of PE is thought to involve insufficient placental perfusion resulting from the lack of trophoblast invasion and remodeling of spiral arteries at early stage of pregnancy[3], in which the soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF) were found to be important mediators. As the antagonist of PlGF, the imbalance of sFlt-1 and PlGF, might lead to vasoconstriction and endothelial dysfunction of placenta formation and subsequent symptoms of PE [4]. The predictive value of sFlt-1/PlGF ratios for PE has been previously researched in general population.. Verlohren et al. established the cutoffs of sFlt-1/PlGF ratio ≤34 to rule out PE occurrence, while sFlt-1/PlGF ratio ≥85 and ≥110 to rule out PE occurrence at <34 and ≥34 weeks of gestation, respectively[5]. More recently, Zeilser et al. verificated that the ratios of sFlt-1/PlGF at 38 or below had superior negative predictive value on PE among symptomatic European patients and the cutoff was replicated in Asian population across 25 centers[6].
At present, the Elecsys immunoassay (Roche Diagnosis) has been accpted as the standard assay for sFlt-1 and PlGF in the early prediction of PE in many Obstetrics centers, in which the applicable population were normal pregnancies [7]. While PE is almost always subsequent to hypertensive manifestations. In the latest guidelines for HDP (hypertension in pregnancy), the diagnosis of PE could be established by hypertension in conjugation with other end-organ dysfunctions in the absence of proteinuria[8]. Studies have shown that 40-50% of women with hypertensive symptoms, regardless gestational or chronic, will develop proteinuria or other end-organ damages that meet the criteria for PE [9]. In the absence of reliable indicators, a large number of hypertensive patients in pregnancy often need to be hospitalized to rule out PE, while some may be ignored and develop severe PE features in a short period of time [10]. As sFlt-1/PlGF has shown excellent predictive value for PE in normal pregnancy, it is also of clinical significance to explore the application of this ratio to predict PE in pregnant women when abnormal BP is present.
The objective of this study is to evaluate the predictive performance and optimal Kryptor specific threshold value for sFlt-1/PlGF ratios on PE among the hypertensive pregnant women, including gestational hypertension and chronic hypertension, in order to improve prognosis and intervention for these patients in future.