MUST — Malnutrition Universal Screening Tool
BMI score
Unplanned weight loss score (past 3–6 months)
The Malnutrition Universal Screening Tool (MUST) is a validated, five-step malnutrition screening tool developed by the British Association for Parenteral and Enteral Nutrition (BAPEN) and recommended by NICE for use across all healthcare settings — community, primary care, hospital outpatient, and inpatient settings. Unlike NRS-2002 (which is hospital-specific), MUST is uniquely validated for use across all care environments, making it particularly valuable for identifying at-risk patients in the community before they require hospitalisation. MUST comprises three components: (1) BMI Score — 0 if BMI >20 kg/m²; 1 if BMI 18.5–20; 2 if BMI <18.5. (2) Weight Loss Score — 0 if unintentional weight loss <5% in the last 3–6 months; 1 if weight loss 5–10%; 2 if weight loss >10%. (3) Acute Disease Effect Score — adds 2 points if the patient is acutely ill and has been or is likely to have no nutritional intake for more than 5 days. The three component scores are summed: a total of 0 indicates low malnutrition risk (routine clinical care); 1 indicates medium risk (observe and review); 2 or above indicates high risk (initiate nutritional support or refer to dietitian). MUST has been validated across diverse populations including elderly community-dwellers, hospital inpatients, care home residents, and oncology patients. It demonstrates good sensitivity, specificity, and inter-rater reliability, correlating with clinical outcomes including length of hospital stay, hospital readmission, and mortality. MUST is recommended by NICE guidance on nutrition support (CG32) and should be performed at first clinical contact and repeated at every subsequent care setting transition.
MUST = BMI Score (0–2) + Weight Loss Score (0–2) + Acute Disease Effect Score (0 or 2); 0 = low risk; 1 = medium risk; ≥2 = high risk
- 1Step 1 — BMI Score: measure height and weight; calculate BMI = weight(kg)/height(m)²; score 0 if BMI >20; score 1 if BMI 18.5–20; score 2 if BMI <18.5.
- 2Step 2 — Weight Loss Score: enquire about unintentional weight loss in the past 3–6 months; score 0 if <5% loss; score 1 if 5–10% loss; score 2 if >10% loss.
- 3Step 3 — Acute Disease Effect Score: assess whether the patient is acutely ill and has been or is likely to have very little (nil or negligible) nutritional intake for >5 days; if yes, score 2; if no, score 0.
- 4Step 4 — Add all three scores to obtain overall MUST score.
- 5Step 5 — Manage according to risk: MUST 0 (low) = routine care; MUST 1 (medium) = observe, document dietary intake for 3 days, re-screen; MUST ≥2 (high) = refer to dietitian, initiate nutritional support, re-screen.
- 6Document MUST score in medical record and communicate between care settings at discharge.
- 7Repeat MUST at every transition between care settings (e.g., discharge from hospital to community) and at least monthly in community settings.
Low MUST does not mean nutritional needs are met — dietary advice may still be appropriate
A well-nourished patient with no weight loss or acute illness has a MUST of 0 and requires only routine nutritional care.
Even without acute illness, significant weight loss + low BMI = MUST ≥2
This patient's low-normal BMI and moderate weight loss together produce a MUST of 2 (high risk), requiring active nutritional intervention.
The acute disease score (2 points) alone can generate high risk even in previously well-nourished patients
A patient who cannot eat for more than 5 days due to bowel obstruction scores maximum points on the acute disease component, even if BMI and weight history are normal.
Severe malnutrition in a nursing home resident requires aggressive assessment for underlying cause (dementia, depression, dysphagia, dental problems, social isolation)
A maximum malnutrition score of 4 in a nursing home resident requires urgent multidisciplinary attention to identify treatable causes and initiate nutritional support.
Universal malnutrition screening at all first care contacts across hospital, GP surgery, care home, and community nursing visits.
Community nursing and GP: identifying housebound elderly patients with progressive weight loss and declining food intake for early dietitian referral.
Pre-operative assessment: MUST ≥2 in surgical patients triggers pre-operative nutritional optimisation to reduce post-operative complication rates.
Oncology: screening before each chemotherapy cycle to detect treatment-related decline in nutritional status early.
Care home surveillance: monthly MUST screening of residents enables early detection of unexplained weight loss before acute illness and hospitalisation occurs.
Frailty and Sarcopenia
Frailty and sarcopenia (loss of muscle mass and function) often coexist with malnutrition but may not be detected by MUST alone. A patient with sarcopenic obesity (normal or high BMI with low muscle mass) may score 0 on MUST yet be nutritionally compromised. Grip strength measurement (handgrip dynamometry), calf circumference, and gait speed tests complement MUST in identifying frailty-associated malnutrition. Resistance exercise combined with protein supplementation is the most effective intervention for sarcopenia.
MUST in Paediatrics
MUST is validated for adults only (≥16–18 years). For children, separate validated tools are used: STAMP (Screening Tool for the Assessment of Malnutrition in Paediatrics) and PYMS (Paediatric Yorkhill Malnutrition Score) are used in hospital; PREW (Paediatric Risk of Malnutrition Tool) and WHZ (weight-for-height z-score) are used in community settings. Paediatric malnutrition definitions use WHO or CDC growth chart percentiles rather than adult BMI thresholds.
MUST and Cancer
Cancer patients have exceptionally high rates of malnutrition and should be screened with MUST at every oncology appointment (pre-chemotherapy, pre-radiotherapy, at surgical consultations). MUST ≥2 in a cancer patient triggers intensive nutritional support, given that malnutrition is directly associated with poorer chemotherapy tolerance, higher toxicity rates, and shorter survival. The PG-SGA (Patient-Generated Subjective Global Assessment) provides more detailed nutritional assessment specifically for oncology patients.
Dysphagia and MUST
Patients with dysphagia (stroke, head and neck cancer, motor neurone disease, dementia) are at very high malnutrition risk because they cannot safely eat normal food textures. MUST screening should be combined with a standardised dysphagia assessment (e.g., GUSS — Gugging Swallowing Screen) in stroke patients. IDDSI (International Dysphagia Diet Standardisation Initiative) provides a framework for prescribing texture-modified foods and drinks at six levels of modification.
| MUST Score | Risk Level | Hospital Management | Community Management |
|---|---|---|---|
| 0 | Low | Routine care; re-screen weekly | Routine care; re-screen monthly if clinical concern |
| 1 | Medium | Observe; food diary for 3 days; dietary advice | Dietary advice; GP review; re-screen in 1 month |
| ≥2 | High | Dietitian referral; ONS; enteral nutrition if needed; treat underlying cause | Urgent GP review; ONS prescription; dietitian; community nursing input |
When should MUST be performed?
NICE and BAPEN recommend MUST be performed: at first contact with any care setting (hospital admission, GP visit, nursing home admission), at every transition between care settings (hospital to community, community to nursing home), and at regular scheduled intervals (weekly in hospital, monthly in community settings for at-risk patients). In practice, all GP surgeries, hospitals, and care homes should have systems in place to ensure universal MUST screening.
What should be done when BMI cannot be measured?
When height cannot be measured directly (e.g., bed-bound patients), MUST provides alternative methods: knee height measurement (converted to height using validated equations), ulnar length (from olecranon to midwrist styloid — correlated to height using validated charts), or mid-upper arm circumference (MUAC: <23.5 cm suggests low BMI in most adults). When weight cannot be measured, subjective clinical assessment (loose clothes, sunken temples, wasted muscles) can substitute.
How does MUST management differ by risk level?
Low risk (MUST 0): routine care — no specific nutritional intervention but maintain good dietary habits. Medium risk (MUST 1): observe for 3 days; document food and fluid intake; if insufficient (<75% of requirements), provide dietary advice and encourage food fortification; re-screen in 1 week (hospital) or 1 month (community). High risk (MUST ≥2): refer to dietitian; provide oral nutritional supplements (ONS); if oral intake insufficient, consider enteral tube feeding; treat underlying cause; re-screen weekly (hospital) or monthly (community).
Is MUST suitable for specific disease populations?
MUST was validated in general adult populations but has been studied in oncology, HIV, IBD, renal disease, elderly care, and surgical patients. It performs reasonably well across these groups but may underestimate malnutrition in some disease-specific populations (e.g., muscle wasting in liver disease, where ascites inflates weight and BMI). Disease-specific tools (SGA for renal disease; PG-SGA for oncology; Royal Free Global Assessment for liver disease) may be more sensitive in these contexts.
What is the relationship between MUST and pressure ulcer risk?
Malnutrition and pressure ulcers are closely linked — malnourished patients have greater tissue fragility, impaired immune function, and slower wound healing. MUST and the Braden Pressure Ulcer Risk Assessment often flag the same high-risk patients. MUST scores ≥2 should trigger both a nutritional intervention and a skin care/pressure ulcer prevention plan. Protein supplementation is particularly important for both preventing and healing pressure ulcers.
Can MUST predict hospital outcomes?
Multiple validation studies have demonstrated that MUST ≥2 at hospital admission is independently associated with significantly longer hospital stay (average 5–7 extra days), higher complication rates (wound infection, pneumonia, falls), greater 30-day mortality, and higher 30-day readmission rates. Addressing high MUST with dietitian-led nutritional intervention has been shown to reduce these adverse outcomes in randomised trials.
What oral nutritional supplements (ONS) are available?
ONS are nutritionally complete liquid or semi-solid supplements providing 200–600 kcal and 8–25 g protein per serving. They are available as standard energy (1.0–1.5 kcal/mL), high energy (2.0 kcal/mL), high protein, fibre-containing, disease-specific (renal, diabetic, oncology), and texture-modified varieties. NICE recommends prescribing ONS for at least 1 month in high-risk patients and reviewing response before deciding on continuation. Compliance is improved by providing choice of flavours and formats.
What is the difference between MUST and mini nutritional assessment (MNA)?
The Mini Nutritional Assessment (MNA) is specifically validated for older adults (≥65 years) and includes additional geriatric domains not captured by MUST: mobility, neuropsychological problems, pressure sores, number of medications, and dementia assessment. The MNA has a two-step structure (screening form MNA-SF, followed by full MNA if needed) and is recommended for comprehensive geriatric assessment in nursing home and elderly hospital settings. MUST is suitable for all ages; MNA is preferred for formal nutritional assessment in older adults.
Pro Tip
The MUST provides objective, reproducible malnutrition risk stratification, but it must always be combined with clinical observation. A patient who 'looks thin', has obviously lost weight since their last appointment, or whose clothes no longer fit should be scored as high-risk even if the formal MUST calculation gives a lower score. Clinical judgement is the backstop for every screening tool.
Did you know?
The MUST tool was launched by BAPEN (British Association for Parenteral and Enteral Nutrition) in 2003 following a national audit that found hospital malnutrition was severely under-recognised and under-treated in UK hospitals. A 2007 BAPEN report estimated that malnutrition cost the NHS approximately £13 billion annually at that time — more than obesity — yet received a fraction of the public health attention. This disparity prompted NICE to issue mandatory malnutrition screening guidance (CG32) in the same year.