Clinical Information

Preeclampsia (PE) is a complication of pregnancy that affects approximately 5% of women worldwide. Preeclampsia is a serious hypertensive condition occurring at mid-pregnancy. Clinical signs of PE, such as the onset of hypertension, are typically observed after 20 weeks of gestation. Clinically, PE may vary from mild to severe forms, and may require premature delivery. The severe form of PE, which may include symptoms of the life-threatening HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome, occurs in about 20% of women presenting with PE. While early-onset PE (which develops before 34 weeks of gestation) is less prevalent than late-onset PE (which develops at 34 weeks of gestation or later), early onset PE is associated with a greater risk of adverse outcome.

Although the cause of PE remains unclear, the syndrome may be initiated by an imbalance of placental factors that induce endothelial dysfunction. Soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PIGF) are both associated with placental dysfunction and risk of PE during pregnancy. Women with PE have been reported to have increased circulating concentrations of sFlt-1, an antiangiogenic protein largely produced in the placenta, which is associated with inhibition of vascular endothelial growth factor and PlGF. During pregnancy, PlGF concentrations typically increase progressively in the first and second trimester and then decrease towards full term. In contrast, in cases of clinical PE, sFlt-1 concentrations are significantly increased versus concentrations observed in normal pregnancies, while concentrations of circulating free PlGF are significantly decreased relative to normal pregnancy.

The use of the sFlt-1/PIGF ratio has been shown to be a useful tool to aid in risk assessment of patients with clinical signs and symptoms consistent with development of PE with severe features (as defined by American College of Obstetricians and Gynecologists guidelines)(1). Based on the data collected during the PRAECIS clinical study, the prognostic performance of the sFlt-1/PIGF ratio using a ratio cut-off of 40 (where if the ratio is greater than or equal to 40, there is a high risk for progression to PE with severe features), exhibited a sensitivity of 94%, and specificity of 75% for the development of PE with severe features within 2 weeks. The performance of the sFlt-1/PlGF ratio to predict development of PE with severe features within two weeks was statistically higher than the prognostic performance of other commonly used clinical (highest systolic blood pressure, highest diastolic blood pressure) and laboratory (eg, aspartate aminotransferase, alanine aminotransferase, creatinine, and platelets) markers associated with PE.