Comparison of the efficacy for early warning systems in predicting obstetric critical illness

Abstract

Objective: To validate the accuracy of four early warning scores for early identification of women at risk for deterioration. Study Design: This was a retrospective study of pregnant women admitted in the obstetrics Critical Care Unit (ICU) from August 2019 to August 2020.The capacity of the Modified Obstetric Early Warning Score (MOEWS), ICNARC Obstetric Early Warning Score (OEWS), Maternal Early Obstetric Warning System (MEOWS chart), and Maternal Early Warning Trigger (MEWT) were compared in in predicting severe maternal morbidity. All scoring systems were calculated 24 hours after admission in ICU. The area under receiver operator characteristic (AUROC) curve was used to evaluate the predictive performance of the scoring system. Results: A total of 352 pregnant women were enrolled, 290 women with severe maternal morbidity were identified and two of them died. Gestational age in group of critically ill were shorter than the group of not critically ill (33.13±0.267 vs. 35.79±0.47, p<0.001). Both the length of ICU stay (3.503±0.314 vs. 1.758±0.994, p<0.001) and total length of stay (9.724±0.379 vs. 6.984±0.319, p<0.001) were longer in women with critically ill. MOEWS was more sensitive than MEOWS chart, ICNARC OEWS and MEWT (96.9% vs. 83.4%, 66.6% and 44.8%). However, MEWT had the highest specificity (98.4%), followed by MOEWS (83.9%), ICNARC OEWS (75.8%) and MEOWS chart （48.4%）. AUROC of MOEWS, ICNARC OEWS, MEOWS chart, and MEWT for prediction of maternal mortality were 0.91 (95% CI: 0.874-0.945), 0.765(95% CI: 0.71-0.82), 0.657(95% CI: 0.577-0.738), and 0.716 (95% CI, 0.659-0.773) respectively. Furthermore, MOEWS had the highest AUCs in the discrimination of serious complications in hypertensive disorders, cardiovascular disease, obstetric hemorrhage and infection. Additionally, among the individual vital signs, maximum diastolic blood pressure (DBP) was the most predictive and followed by maximum systolic blood pressure (SBP) , maximum respiratory rate (RR) and peripheral oxygen saturation(SPO2), the AUCs were 0.626(95% CI, 0.564-0.689), 0.616 (95% CI, 0.553-0.679), 0.607 (95% CI, 0.542-0.672) and 0.321(95%CI, 0.262-0.381) in turn. Conclusion: MOEWS is significantly more accurate than ICNARC OEWS, MEOWS chart, and MEWT in the performance for predicting the deterioration of obstetric patient. The prediction ability of DBP, SBP, RR and SPO2 are more reliable.