Validation of a modified obstetric early warning system for predicting severe maternal outcome at Moi Teaching and Referral Hospital, Eldoret

Abstract

Background: Maternal death remains high in developing countries. Mothers who survive complications suffer severe morbidity. These mothers, termed, ‘near-miss’ are defined by World Health Organization(WHO) as women who nearly died from a complication that occurred during pregnancy, childbirth or within 42 days of delivery. Near-miss cases and maternal deaths constitute severe maternal outcome (SMO). To prevent SMO, a system known as Modified Early Obstetric Warning System (MOEWS) for tracking significant changes (‘triggers’) in vital signs among obstetric patients and initiating corrective measures is suggested. The use of the MOEWS in Moi Teaching and Referral Hospital (MTRH) and Kenya remains limited, and its ability to predicting SMO remains unexplored. Objective: To determine the validity of the MEOWS for predicting SMO, the vital sign triggers that are associated with SMO and perinatal outcomes of mothers with SMO at MTRH, Eldoret Methods: A retrospective cohort study was conducted at Riley Mother and Baby Hospital, MTRH, among mothers admitted consecutively and discharged or died from 1st January 2019 up to when the desired sample size of 3200 patients was achieved. Maternal mortality was established as defined by WHO. Maternal near-miss was defined by WHO clinical, Intervention-based and Disease-based criteria Mothers were grouped into two outcome groups; either experiencing or not experiencing SMO. Their vital signs 24 hours prior to either outcome were then tabulated on a MOEWS chart and determined whether they met a vital sign trigger threshold. The sensitivity, specificity, positive predictive value(PPV) and negative predictive value(NPV) were determined. Associations were determined between the various vital signs and occurrence of SMO. Perinatal outcomes were also determined. Results: Majority of patients were aged 20 to 34 years, were married and attained secondary level education. The sociodemographic and obstetric factors associated with occurrence of SMO were age over 35 years(aOR=1.56), having a previous caesarean delivery(aOR=2.19), caesarean delivery in the index pregnancy(aOR=2.09), being a referral(aOR=3.43), not attending antenatal care (aOR=2.53) and admission in the period between 28 to 37 weeks(aOR=2.81) and in the postpartum period(aOR 51.3). The sensitivity of MOEWS was 77%, specificity 98%, PPV 61% and NPV 98%. Vital signs independently associated with occurrence of SMO were heart rate(aOR 30.61), respiratory rate(aOR 3.36), systolic blood pressure(aOR 12.8) and diastolic blood pressure(aOR 45.8). Neonates born to mothers with SMO had higher rates of still birth, low birth weight and admission to newborn unit. Conclusion: The MOEWS chart has a high specificity and NPV but low sensitivity and PPV. Triggers for respiratory rate, heart rate, diastolic and systolic blood pressure are likely to be associated with SMO. Mothers with SMO are most likely to have adverse fetal outcomes. Recommendation: The MOEWS chart is an important tool for screening high risk patients for SMO such as mothers with severe preeclampsia, referrals, mothers admitted at less than 37 weeks and postnatal mothers. Provision of specialized neonatal care for babies born to mothers with SMO should be anticipated.