Malnutrition is a common and often under-recognised problem in hospitalised patients. It is associated with increased risk of infection, poor wound healing, prolonged hospital stay, and higher mortality.
Early identification is essential. The Malnutrition Universal Screening Tool (MUST) is a validated and widely used tool to identify adults at risk of malnutrition and guide further management. This article provides a practical overview of how to perform and interpret MUST scoring on the ward and is the fourth article in our series exploring risk assessements in clinical practice.
Contents
When to Perform MUST Assessment
Malnutrition screening should be carried out:
- On admission (within 24 hours)
- Weekly during hospital stay
- If there is a change in clinical condition
Screening is particularly important in patients with:
- Weight loss
- Poor oral intake
- Frailty or chronic disease
- Prolonged hospitalisation
What is the MUST Score?
The MUST score is a 5-step screening tool based on three core components:
- Body Mass Index (BMI)
- Unintentional weight loss
- Acute disease effect
Each component is scored, and the total determines the patient’s risk of malnutrition.
Step 1: BMI Score
Calculate BMI using weight and height.
| BMI (kg/m²) | Score |
|---|---|
| >20 | 0 |
| 18.5–20 | 1 |
| <18.5 | 2 |
A lower BMI is associated with higher malnutrition risk.
Step 2: Unintentional Weight Loss
Assess percentage weight loss over the past 3–6 months.
| Weight Loss | Score |
|---|---|
| <5% | 0 |
| 5–10% | 1 |
| >10% | 2 |
Unintentional weight loss is a key indicator of nutritional decline.
Step 3: Acute Disease Effect
Assign a score if:
- The patient is acutely unwell, AND
- There has been or is likely to be no nutritional intake for >5 days
| Criteria | Score |
|---|---|
| No | 0 |
| Yes | 2 |
This reflects the rapid impact of acute illness on nutritional status.
Step 4: Calculate Total Score
Add the scores from Steps 1–3:
- 0 → Low risk
- 1 → Medium risk
- ≥2 → High risk
Step 5: Interpretation and Action
Low Risk (Score 0)
- Routine clinical care
- Repeat screening weekly in hospital
Medium Risk (Score 1)
- Observe and document dietary intake
- Repeat screening more frequently
- Escalate if intake remains poor
High Risk (Score ≥2)
- Initiate nutritional support
- Refer to dietitian or nutrition team
- Monitor regularly and implement care plan
Management should be individualised based on clinical context.
Practical Considerations on the Ward
- Use actual measurements where possible (weight, height)
- If unavailable, consider alternatives (e.g. mid-upper arm circumference)
- Ensure accurate documentation of weight history
- Repeat assessments regularly—risk can change quickly
The MUST score should inform, but not replace, clinical judgement.
Common Pitfalls
- Not obtaining a reliable weight history
- Estimating rather than measuring BMI
- Missing the acute disease component
- Failing to repeat screening during admission
Key Principles
- Malnutrition is common and clinically significant
- MUST is a simple, validated screening tool used across the NHS
- It is based on BMI, weight loss, and acute illness
- A score of ≥2 indicates high risk
- Screening should be repeated regularly and acted upon
Written by Dr A Sidhu (CT2)
