The accuracy of the soluble fms-like tyrosine kinase 1/placental growth factor ratio assay in predicting time to delivery in patients with suspected preeclampsia.

Wilson, S.; Carson, E.; Fu, L.; Yip, PM.; Hladunewich, MA.; Kingdom, J.; Melamed, N.

The accuracy of the soluble fms-like tyrosine kinase 1/placental growth factor ratio assay in predicting time to delivery in patients with suspected preeclampsia.

All Authors

Wilson, S.

Carson, E.

Fu, L.

Yip, PM.

Hladunewich, MA.

Kingdom, J.

Melamed, N.

LTHT Author

Carson, Elaine

LTHT Department

Women's Services
Obstetrics & Gynaecology
Fetal Medicine

Publication Date

2026

Item Type

Journal Article

Subject

ANGIOGENESIS , ADRENAL CORTEX HORMONES , PRENATAL CARE , HYPERTENSION , PLACENTA , PRE-ECLAMPSIA , OBSTETRIC LABOUR, PREMATURE , PROGNOSIS , PROGNOSIS , RISK

Abstract

OBJECTIVE: Preeclampsia is a leading cause of maternal and fetal morbidity and mortality, but its clinical course is often difficult to predict. This can make management decisions, such as admission and administration of antenatal corticosteroids, challenging. Abnormal levels of the angiogenic proteins soluble fms-like tyrosine kinase 1 and placental growth factor have been shown to improve the diagnostic accuracy for preeclampsia. However, data on their accuracy in predicting time to delivery are limited. The objective of the present study was to fill this critical gap. STUDY DESIGN: A retrospective cohort study of patients with a singleton pregnancy in a single center evaluated for suspected preeclampsia using the Roche Elecsys soluble fms-like tyrosine kinase 1/placental growth factor ratio assay between 2020 and 2023. Modified Poisson regression and Cox regression survival analysis were used to estimate the association between the soluble fms-like tyrosine kinase 1/placental growth factor ratio and the risk of delivery within 7 days. The soluble fms-like tyrosine kinase 1/placental growth factor ratio was interpreted as low risk (<=38), moderate risk (>38-85), or high risk (>85). RESULTS: A total of 503 patients met the study criteria. The preeclampsia rate was 39.8% (n=200). The soluble fms-like tyrosine kinase 1/placental growth factor ratio was inversely associated with the testing-to-delivery time (Spearman's Rho, -0.63 [the confidence interval is -0.73 to 0.63]). Survival analysis revealed that moderate-risk and high-risk ratios were associated with shorter testing-to-delivery intervals than a low-risk ratio (adjusted hazard ratio, 1.7 [95% confidence interval, 1.2-2.3] and adjusted hazard ratio, 5.1 [95% confidence interval, 3.8-6.9], respectively). A low-risk ratio (<=38) was associated with a high negative predictive value for birth within 7 days (89% [95% confidence interval, 83%-96%]), especially when found before 34 weeks (99% [95% confidence interval, 97%-100%]). The positive predictive value of a high-risk ratio (>85) for delivery within 7 days was 65% (95% confidence interval, 56%-75%). To achieve a more clinically relevant positive predictive value of 80%, higher soluble fms-like tyrosine kinase 1/placental growth factor ratio cutoff values were required: 365 in the overall cohort, 368 in cases tested before 34 weeks, and 300 in those tested at >=34 weeks. CONCLUSION: The soluble fms-like tyrosine kinase 1/placental growth factor ratio is a useful prognostic tool for predicting time to delivery in patients with suspected preeclampsia and can therefore guide management decisions, such as admission and the administration of antenatal corticosteroids.