Prospective Study Evaluating the Association Between sFlt-1/PlGF Ratio and Adverse Outcomes in Preterm Preeclampsia.

Objectives: To estimate the association between maternal soluble Fms tyrosine kinase 1 to placental growth factor (sFlt-1/PlGF) ratio and adverse outcomes related to preterm preeclampsia.

Methods: We performed a prospective study including participants with preeclampsia between 24 and 36 weeks of gestation. The sFlt-1/PlGF ratio was measured in maternal serum at admission and was reported according to pregnancy outcomes (delivery in <7 days after admission, severe preeclampsia before term, and serious complications, including stillbirth; eclampsia; hemolysis, elevated liver enzymes, and low platelet syndrome; and acute renal failure). Receiver-operator characteristics curve analyses using the Youden index were used to determine optimal sFlt-1/PlGF ratio thresholds.

Results: Of 467 participants (median gestation: 34 weeks; IQR 31-36), 373 (80%) delivered in <7 days after admission; 387 (83%) developed severe preeclampsia before term, including 18 (4%) with serious complications. Three sFlt-1/PlGF threshold values were identified: 68, 250, and 500. SFlt-1/PlGF ratios less than 68, between 68 and 249, between 250 and 299, and ≥500 were associated with delivery in <7 days after admission (in 54%, 73%, 88%, and 91%, respectively, P < 0.001), with severe preeclampsia before term (in 51%, 77%, 86%, and 88%, respectively, P < 0.001) and with serious complications (in 0%, 0%, 3%, and 8%, respectively, P < 0.001). The higher the ratio, the lower the interval between admission and birth (4 days [IQR 0-21], 1 [IQR 0-8], 0.5 [IQR 0-2], and 0 [IQR 0-2], respectively, P < 0.01).

Conclusions: Among women with preterm preeclampsia, an sFlt-1/PlGF ratio >250 is associated with short admission to delivery interval, severe preeclampsia, and serious complications.