Comparison of performance of shock index and conventional vital sign parameters for prediction of adverse maternal outcomes following major postpartum hemorrhage in Abakaliki, Southeast Nigeria

Background: Despite advances in care, postpartum hemorrhage has continued to contribute disproportionately to maternal morbidity and mortality in developing countries due to delayed and/or substandard care in the diagnosis and management of hypovolemic shock. Aim: To compare the performance of the shock index with conventional vital signs for prediction of maternal outcome following postpartum hemorrhage and to establish alert thresholds for use in low-resource settings. Materials and Method: This is a 7-year retrospective cohort study of 289 women treated for primary postpartum hemorrhage at the Alex Ekwueme Federal University Teaching Hospital, Abakaliki. The data for systolic and diastolic blood pressure, mean arterial pressure, pulse pressure, heart rate, and shock index measured at the time of diagnosis of postpartum hemorrhage were analyzed. Adverse maternal outcomes such as intensive care unit admission, blood transfusion ≥5 units, hemoglobin level <7 g/dL, surgical interventions, end-organ failure, and death were reviewed. The area under the receiver operating characteristic curve (AUROC) for each vital sign was used to predict adverse maternal outcomes. Sensitivity, specificity, and negative and positive predictive values were calculated to determine the thresholds of the best predictor. Results: Shock index had the highest AUROC to predict invasive surgical procedures (0.70 for SI [95% CI 0.66–0.80] compared with 0.69 [95% CI 0.61–0.76] for pulse rate). Shock index was a consistent superior predictor for other outcomes. Shock index (SI) ≥0.9 had 100% sensitivity (95% CI 74.6–100) and 46.7% specificity (95% CI 34.9–56.5) for prediction of intensive care admission, and SI ≥1.7 had 46.9% sensitivity (95% CI 19.8–62.8) and 98.9% specificity (CI 91.1–100) for prediction of maternal death. Conclusion: Shock index is a consistent superior predictor of adverse maternal outcomes following postpartum hemorrhage when compared with conventional vital signs. SI <0.9 provides reassurance, whereas SI ≥1.7 indicates a need for urgent intervention to prevent maternal mortality.