What is the range of calculated Modified Early Warning Score (MEWS)?

Modified Early Warning Score (MEWS) Range

The Modified Early Warning Score (MEWS) ranges from 0 to 15, with scores calculated from routine ward observation data including vital signs and level of consciousness. 1

Score Composition and Calculation

• MEWS is an aggregated weighted scoring system that combines five physiological parameters: systolic blood pressure, pulse rate, respiratory rate, body temperature, and level of consciousness 2
• The score can be calculated from routine ward observation data without requiring electronic systems, making it practical for bedside use 1
• Each parameter is assigned points based on degree of deviation from normal, with the total score representing the sum of all component scores 2

Clinical Risk Stratification by Score Bands

• MEWS of 0 indicates very low risk, with patients having minimal probability of death or clinical deterioration (OR 0.14,95% CI: 0.08-0.24) 2
• MEWS bands 0-2 represent lower risk categories where cardiac arrest rates are not significantly elevated 1
• MEWS bands 3-4 indicate moderate risk, with significantly higher cardiac arrest rates observed in these ranges 1
• MEWS bands 5-15 represent higher risk categories, though the specific threshold for intervention varies by institution 1

Evidence-Based Risk Thresholds

• A MEWS of 7 or higher has been used as a "warning zone" in validated protocols, with cardiac arrest rates of 1.40% at score 7,1.75% at score 8, and 3.57% at score 9 or more 3
• Incremental risk of death increases across all MEWS categories, with highly significant trends for both mortality and combined outcomes of death or transfer (p < 0.00001) 2
• MEWS shows significant increase in the hours preceding cardiac arrest, rising from mean 3.95 at 12 hours before arrest to 5.98 at 1 hour before arrest (p ≤ 0.001) 4

Clinical Application Context

• MEWS is highly predictive of major adverse events when used in surgical inpatients, though it requires integration with other clinical criteria rather than use in isolation 1
• The American Heart Association notes that MEWS and similar composite risk scores increase discrimination for detection compared with single-parameter criteria 1
• Implementation should include specific intervention thresholds tied to rapid response team activation to maximize potential for improved outcomes 1

Important Caveats

• MEWS alone is not sensitive enough and requires supplementation with other alerting criteria such as clinical concern ("worried") for optimal early detection 1
• The optimal cutoff threshold varies by institution and should be guided by available resources, calculation methods, and system capabilities 1
• High levels of adherence to specific intervention protocols are necessary once MEWS thresholds are reached to achieve mortality reduction 1