Preeclampsia is a major complication of pregnancy and is associated with significant fetal and maternal morbidity and mortality. Timely prediction of preeclampsia facilitates referral of potential patients to an adequate tertiary center, which helps reduce adverse outcomes associated with the disease. Moreover, by accurately ruling out preeclampsia, patients can be discharged safely and relieved of anxiety. Numerous candidate biomarkers have been proposed for the diagnosis and prediction of preeclampsia. Among these, maternal circulating factors such as soluble FMS-like tyrosine kinase-1 (sFlt-1), an anti-angiogenic factor, and placental growth factor (PlGF), an angiogenic factor, are considered the most promising. Measuring these factors as a ratio allows assessment of the angiogenic imbalance that characterizes incipient or overt preeclampsia. The sFlt-1/PlGF ratio increases before the onset of preeclampsia and thus may help predict the disease. The test is used as a predictive tool in several countries but not yet routinely performed in Japanese hospitals.

We performed a systematic review of studies that assessed the performance of the sFlt-1/PlGF ratio in predicting preeclampsia in Japanese patients. Three studies were included in the systematic review. All studies reported high negative predictive values of the sFlt-1/PlGF ratio (i.e., for ruling out PE), in agreement with the current evidence of the test performance worldwide. The sFlt-1/PlGF ratio could be of significant relevance in the Japanese population.