Sflt1/plgf Ratio as a Predictor of Development of Preeclampsia and Adverse Maternal and Perinatal Outcomes in Women at Kenyatta National Hospital, Nairobi Kenya

Abstract

Background: Preeclampsia affects 2-8% of pregnancies globally. In Kenya the prevalence is 5.6-6.5%. Preeclampsia/eclampsia causes 20% of direct maternal deaths in Kenyatta National Hospital (KNH). The diagnostic criteria for preeclampsia are proteinuria and elevated blood pressure beyond 20 weeks gestation. Maternal organ damage and adverse outcomes might happen before proteinuria becomes apparent. There is no single approved predictor of development of preeclampsia. Vascular endothelial growth factors; fms like tyrosine kinase: placental growth factor ratio(sFlt-1/PlGF), have shown promising results as predictors because they are elevated up to 1 month before development of preeclampsia. Objective: To determine the utility of the sFlt-1/PIGF ratio as a predictor of the development of preeclampsia within 4 weeks and adverse outcomes in women at risk of preeclampsia in KNH. Methodology: This was a prospective cohort study in which women between 24+0 to 36+6 weeks of gestation with risk factors for preeclampsia were enrolled, serum sFLT-1: PlGF measured, and then followed up to 24 hours post-partum to determine those who developed PE and adverse maternal and perinatal outcomes. It was conducted at Kenyatta National Hospital antenatal clinics. A sample of 50 women was obtained by consecutive sampling. A questionnaire was filled and data obtained was analysed using SPSS version 23. Demographic and clinical characteristics were summarized as median with interquartile range and frequencies with proportions. sFlt-1/PlGF ratio cut off of <38 was used to rule out preeclampsia within 1 week and >=38 to rule it in within 4 weeks and predict adverse maternal and perinatal outcomes. Sensitivity, specificity, negative and positive predictive values were calculated for the above outcomes. Best cut off to rule in preeclampsia within 4 weeks was determined using a receiver operating curve(ROC). Results: 50 women with high risk for PE were recruited from the antenatal clinic between May and September 2020.The median sFlt-1/PlGF ratio at baseline for patients who developed preeclampsia within 4 weeks was higher at 24.2 (7.0-58.0) compared with those who did not 2.5 (1.3-3.7) though it was no statistically significant (P 0.005). sFlt-1/PlGF ratio <38 to rule out PE within 1 week had a sensitivity of 20.00%, specificity of 11.76% and a NPV of 60.00% (95% CI, 38.59%-78.17%). A ratio ≥38 to rule in preeclampsia within 4 weeks had a sensitivity of 53.85%, specificity of 93.02%. For predicting adverse perinatal outcomes, a ratio ≥38 had a sensitivity of 41.67%, specificity of 92.11% with PPV of 62.50% (31.76%-85.65%). A ratio of ≥38 for predicting adverse maternal outcomes had a sensitivity of 40.00%, specificity of 86.67% and PPV of 25.00% (8.28%-55.18%). Using an ROC curve, an sFlt-1/PlGF ratio cut off was set at 3.97 to rule in PE within 4 weeks. It had a sensitivity of 100% (75.29%-100%), a specificity of 74.42% (58.83%-86.48%), with an AUC 82.6% (CI, 68.6%-96.6%), PPV of 54.17% (41.51%- 66.30%) Conclusion: The sFlt-1/PlGF ratio cut off of 38 did not have very high NPV for ruling out and PPV for ruling in preeclampsia compared to other studies. A cut off of >3.97 to predict development of PE within 4 weeks and adverse maternal and perinatal outcomes has shown high sensitivity and PPV. Recommendations: Lower cut off value for sFlt-1/PlGF ratio should be considered in our population to predict development of preeclampsia and adverse maternal and perinatal outcomes.