Soluble fms-Like Tyrosine Kinase-1 to Placental Growth Factor Ratio for the Prediction of Preeclampsia in Asymptomatic Women.

OBJECTIVES

The ratio of soluble fms-like tyrosine kinase-1 (sFlt-1) over placental growth factor (PlGF) increases before clinical onset in women with suspected preeclampsia (PE). We aimed to estimate its value in asymptomatic patients.

METHODS

We recruited nulliparous patients in the first trimester, invited to attend a 200-246 and 300-346 weeks' gestation visit for maternal blood sampling used for measurement of the sFlt-1/PlGF ratio (using B·R·A·H·M·S KRYPTOR analyzer). The primary outcome was PE stratified by gestational age at delivery: preterm (<37 weeks) subdivided into early (<34 weeks) and late (34-36 weeks) preterm; and term (≥37 weeks) PE. Analyses included area under the receiver operating characteristic curves and the Youden index.

RESULTS

Among 845 women recruited, 832 (98%) had complete data, including 4 (0.5%) early, 4 (0.5%) late-preterm, and 26 (3.1%) term PE. At 200-246 weeks gestation, the sFlt-1/PlGF ratio was highly associated with early (area under the receiver operating characteristic curve [AUC] 0.99; 95% CI 0.99-1.00; sensitivity: 100% specificity: 99%) but not late-preterm or term PE. At 300-346 weeks, the sFlt-1/PlGF ratio accurately discriminated preterm cases (AUC 0.96; 95% CI 0.89-1.00; sensitivity: 86% specificity: 98%) and moderately discriminated term cases (AUC 0.71; 95% CI 0.58-0.83; sensitivity: 42% specificity: 93%).

CONCLUSIONS

Maternal sFlt-1/PlGF ratio is increased at 20-24 weeks gestation among asymptomatic women who will develop early PE and at 30-34 weeks among those who will develop preterm PE. The discriminatory performance of the sFlt-1/PlGF ratio varies according to gestational age at screening and gestational age at delivery.