Effectiveness of early warning scores in predicting in-hospital mortality and adverse events in adult general-ward patients in low- and middle-income countries: A systematic review

Abstract

Background: Early Warning Score systems (EWSs) based on bedside physiological parameters are widely implemented in high-income countries, yet their performance and utility in low- and middle-income countries (LMICs) remain uncertain, particularly in emergency and acute care settings, due to limited evidence and health system constraints. We systematically reviewed the effectiveness of EWSs for predicting in-hospital mortality and adverse events among adult general-ward patients in LMICs. Methods: This systematic review followed PRISMA 2020 and PRISMA-S guidance and was prospectively registered in PROSPERO (CRD420251029273). We searched PubMed, Scopus, LILACS and African Journals Online (AJOL) from inception to May 2025, with no language restrictions. We included studies enrolling adult general-ward patients in LMICs, and excluded studies conducted solely in intensive care units, emergency departments, paediatric or obstetric populations. Data were narratively synthesised, and risk of bias was assessed using PROBAST. Results: Twenty-eight observational studies comprising a total of 36,638 participants - primarily from sub-Saharan Africa and South Asia - met inclusion criteria. The Modified Early Warning Score (MEWS) and National Early Warning Score (NEWS) were most frequently assessed and generally demonstrated moderate-to-good discrimination for in-hospital mortality, with substantial heterogeneity by setting. The Universal Vital Assessment (UVA) showed promising discrimination relative to MEWS and qSOFA in some resource-limited contexts, however its dependence on HIV testing and laboratory support limits comparability with purely bedside scores. Only a minority of studies examined unplanned ICU admission, cardiac arrest or rapid-response activation. Limitations included substantial heterogeneity in methodology, outcomes, cut-off values and follow-up periods, which limited comparability, as well as the absence of studies originating from Central and South America. Conclusion: Evidence in LMIC wards is largely observational and frequently based on statistical simulations with small samples; it should not be interpreted as proof of clinical effectiveness. Before widespread adoption, rigorous local validation and recalibration, along with multicentre, pragmatic implementation studies, are needed to define thresholds, workflows and escalation pathways appropriate to LMIC health-system capacity.