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The Malnutrition Universal Screening Tool (MUST) is a resource to help identify malnutrition issues and develop a care plan.

What is MUST?

Launched in 2003 and reviewed regularly since then, MUST was developed by the Malnutrition Advisory Group – a standing committee of the British Association for Parenteral and Enteral Nutrition (BAPEN).

It is supported by the RCN and the British Dietetic Association and, according to BAPEN, is the most commonly used screening tool in the UK, and is also used in many other countries in Europe and the rest of the world.

The tool incorporates five steps that practitioners can follow to identify adults who are malnourished, at risk of malnourishment, or obese.

It also includes management guidelines, which can be used to develop a care plan.

Where is MUST used by nurses?

The MUST screening tool can be used by staff in hospitals, care homes and in primary care and is free to use for noncommercial purposes.

In 2013, the National Institute for Health and Care Excellence recommended MUST to healthcare staff as an example of a validated screening tool, to aid implementation of its Quality Standard for Nutritional Support of Adults.

Why is it vital to get MUST right?

East Kent Hospitals University NHS Foundation Trust clinical and service lead in nutrition and hydration Wendy-Ling Relph says: ‘At least 30% of our patients are malnourished when they are admitted. Staff may think they can look at a patient and see if they’re malnourished, but the tool enables us to gain an objective view.’

Ms Relph, who is also a member of the National Nurses Nutrition Group, a BAPEN council member, and chair of the organisation’s nasogastric special interest group, says it is important nurses understand the implications malnourishment can have for patient care.

‘If you’re malnourished, you’re much more likely to fall, take longer to heal, be confused or dehydrated,’ she says.

‘It also increases someone’s length of stay in hospital. Understanding someone’s nourished state is one of the fundamental aspects of nursing care.’

How does the tool work in practice?

Are there any drawbacks to using the tool?

A 2021 audit carried out by South Tyneside and Sunderland NHS Foundation Trust on the quality of its MUST electronic assessments included 25 wards and 124 patients.

It found that while 94% of patients had a MUST completed within 24 hours of admission, only 66% were accurate.

The audit also looked at nurses’ skills and knowledge. Findings highlighted that nurses were not always using alternative measurements to calculate BMI, when the person could not be weighed or their height calculated.

This led to less accurate MUST scores, potentially affecting appropriate interventions. The alternatives – measuring MUAC and the ulna – are taught in the trust’s preceptorship programme and accessible through the trust’s e-learning.

Nurses also experienced difficulties in calculating patients’ weight loss as a percentage, again leading to inaccurate MUST scores.

The trust says it has now scheduled training for ward-based nutrition champions, who can share knowledge with their colleagues. This will include how to carry out a quality MUST assessment and undertake MUAC and ulna measurements.

Ms Relph points out that MUST is one of a number of different screening tools used by nurses to assess various aspects of a patient’s health.

‘One of the barriers is that there can be a lot to undertake when you first admit a patient,’ she says. ‘Although MUST is relatively easy to use, it is vital staff understand why it is so important. Sometimes it can be difficult for nurses to prioritise it, if they don’t understand the rationale.’

If it is not possible to measure weight and height, alternative measures can be used to calculate BMI

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How should MUAC and ulna length be measured?

BAPEN advises that to measure MUAC, the patient’s left arm should be bent at the elbow at a 90-degree angle, with the upper arm held parallel to the side of the body. The distance between the bony protrusion on the shoulder – acromion – and the point of the elbow – olecranon process – should be measured. Mark the mid-point.

Then ask the person to let their arm hang loose and measure around the upper arm at the midpoint, making sure that the tape measure is snug but not tight.

‘The use of MUAC provides a general indication of BMI and is not designed to generate an actual score for use with MUST,’ says the guidance.

For the ulna, measure between the point of the elbow – olecranon process – and the midpoint of the prominent bone of the wrist – styloid process – on the left-hand side, if possible, the guidance says.

Further information

BAPEN (2020) Malnutrition Universal Screening Tool bapen.org.uk/pdfs/must/must_full.pdf

Malnutrition Task Force (2021) Malnutrition in England factsheet malnutritiontaskforce.org.uk/malnutrition-england-factsheet