What is the MEWS Score?
The Modified Early Warning Score (MEWS) is a clinical assessment tool used in hospitals to identify patients who are at risk of deterioration. It is based on five physiological parameters: systolic blood pressure, heart rate, respiratory rate, temperature, and level of consciousness (AVPU scale).
MEWS was developed as a simplified bedside scoring system that can be calculated by any healthcare professional including nurses, medical students, and paramedics. It does not require laboratory results or invasive monitoring, making it practical for use on general hospital wards, emergency departments, and pre-hospital settings.
The score helps standardize the recognition of clinical deterioration, ensuring that patients who need urgent attention are identified quickly. Many hospitals use MEWS as part of their escalation protocols and rapid response team activation criteria.
Scoring Criteria
Each parameter is assigned a score from 0 to 3 based on how far the value deviates from normal. The individual scores are summed to produce the total MEWS.
Systolic Blood Pressure (mmHg)
| SBP Range | Score |
|---|---|
| ≤ 70 | 3 |
| 71 – 80 | 2 |
| 81 – 100 | 1 |
| 101 – 199 | 0 |
| ≥ 200 | 2 |
Heart Rate (bpm)
| HR Range | Score |
|---|---|
| ≤ 40 | 2 |
| 41 – 50 | 1 |
| 51 – 100 | 0 |
| 101 – 110 | 1 |
| 111 – 129 | 2 |
| ≥ 130 | 3 |
Respiratory Rate (breaths/min)
| RR Range | Score |
|---|---|
| < 9 | 2 |
| 9 – 14 | 0 |
| 15 – 20 | 1 |
| 21 – 29 | 2 |
| ≥ 30 | 3 |
Temperature (°C)
| Temperature Range | Score |
|---|---|
| < 35.0 | 2 |
| 35.0 – 38.4 | 0 |
| ≥ 38.5 | 2 |
AVPU (Level of Consciousness)
| Response Level | Score |
|---|---|
| Alert | 0 |
| Reacting to Voice | 1 |
| Reacting to Pain | 2 |
| Unresponsive | 3 |
Score Interpretation
| MEWS Total | Risk Level | Recommended Action |
|---|---|---|
| 0 – 2 | Low Risk | Continue routine monitoring (every 4–6 hours) |
| 3 – 4 | Medium Risk | Increase monitoring frequency (every 1–2 hours); notify charge nurse |
| ≥ 5 | High Risk | Immediate medical assessment required; consider rapid response team activation |
MEWS Escalation Pathway
Clinical Use & Rapid Response
The MEWS score is designed to be used as a track-and-trigger system. When a patient's MEWS reaches a predefined threshold, it triggers a specific clinical response. This approach has been widely adopted in hospitals around the world as part of patient safety initiatives.
Rapid Response Teams (RRT) are specialized teams of critical care clinicians who can be called to the bedside of any patient showing signs of deterioration. In many institutions, a MEWS of 5 or greater automatically triggers an RRT call. Studies have shown that early RRT activation reduces cardiac arrest rates, unplanned ICU admissions, and in-hospital mortality.
Key advantages of using MEWS in clinical practice:
- Simplicity: No laboratory tests required; can be calculated in under a minute
- Standardization: Provides a common language for communicating patient acuity
- Early detection: Vital sign abnormalities often precede cardiac arrest by 6–8 hours
- Reduced failure to rescue: Ensures deteriorating patients are identified before a critical event
- Objective escalation: Removes subjectivity from the decision to escalate care
Evidence & Validation
The MEWS has been validated in multiple clinical studies across different healthcare settings. Subbe et al. (2001) demonstrated that a MEWS of 5 or more was associated with an increased risk of death, ICU admission, or cardiac arrest. Subsequent studies have confirmed its utility in emergency departments, medical wards, and surgical units.
While MEWS is effective, it has limitations. It does not include oxygen saturation, which is addressed in the National Early Warning Score (NEWS). It may be less accurate in certain populations such as patients with chronic respiratory disease or those on beta-blockers. Despite these limitations, MEWS remains widely used due to its simplicity and ease of implementation.
Worked Example
Consider a patient with the following vital signs:
- Systolic BP: 85 mmHg
- Heart Rate: 115 bpm
- Respiratory Rate: 24 breaths/min
- Temperature: 38.8°C
- AVPU: Reacting to Voice
This patient scores 8, which is well above the threshold of 5. This indicates high risk and warrants immediate medical assessment and likely activation of the rapid response team. The combination of hypotension, tachycardia, tachypnea, fever, and reduced consciousness suggests possible sepsis or another serious acute illness.
Frequently Asked Questions
What is the difference between MEWS and NEWS?
MEWS (Modified Early Warning Score) uses five parameters and does not include oxygen saturation. NEWS (National Early Warning Score), developed by the Royal College of Physicians, includes seven parameters: respiratory rate, oxygen saturation, supplemental oxygen use, temperature, systolic blood pressure, heart rate, and level of consciousness. NEWS is generally considered more comprehensive and has largely replaced MEWS in UK hospitals.
How often should MEWS be calculated?
For stable patients with low MEWS (0–2), every 4–6 hours is standard. For patients with medium scores (3–4), every 1–2 hours. For high scores (≥5), continuous monitoring is recommended until the patient has been reviewed by a senior clinician.
Can MEWS be used in pediatric patients?
MEWS is designed for adult patients. Pediatric patients have different normal ranges for vital signs that vary significantly by age. Specific pediatric early warning scores (PEWS) should be used for children.
What should I do if my patient scores 5 or more?
A MEWS of 5 or more requires immediate medical review. In most hospitals, this means activating the rapid response team or medical emergency team. Do not wait for the next routine assessment. Ensure the patient has IV access, continuous monitoring, and that a senior clinician has been notified.