Vital sign-based Early Warning Scores in low- and middle-income countries: a systematic review of clinical effectiveness and implementation challenges

Early recognition of clinically deteriorating patients may improve patient outcomes. Early warning scores (EWS) are widely used in high-income settings, but their effectiveness in low- and middle-income countries (LMICs) remains uncertain. This systematic review evaluates whether the implementation of EWS improves patient outcomes in LMICs and explores factors that may influence their effectiveness. A systematic search was conducted in Pubmed, EMBASE, and the Cochrane Library from database inception to 12 December 2024. Studies comparing patient outcomes before and after EWS implementation in LMICs were included. Outcomes of interest were mortality, length of hospital stay, serious adverse events (SAEs), and intensive care unit (ICU) admissions. Five studies met the inclusion criteria. Overall, EWS implementation was not associated with a consistent reduction in mortality or SAEs. However, two studies reported a shorter length of hospital stays following implementation, and one study demonstrated a reduction in unplanned ICU admissions. The included studies were heterogeneous in design, setting, and patient populations and therefore overall certainty of evidence was low to moderate. Current evidence does not demonstrate an improvement in patient outcomes following the implementation of EWS in LMICs. However, this finding is based on a small number of heterogenous studies with varying methodological quality and should therefore be interpreted with caution. The absence of observed benefits may reflect both limitations of the available evidence and contextual factors, such as limited resources, insufficient training, and restricted escalation capacity. Future research should focus on both clinical effectiveness and implementation factors within LMIC health-care systems.