Malnutrition Universal Screening Tool (MUST)

The Malnutrition Universal Screening Tool (MUST) is a five-step screening instrument developed by the British Association for Parenteral and Enteral Nutrition (BAPEN) to identify adults who are malnourished or at risk of malnutrition. It combines body mass index, unplanned weight loss, and the effect of acute illness on intake into an overall risk score that links to a management pathway.

Definition

MUST is a validated screening tool that combines three parameters - body mass index, percentage unplanned weight loss, and an acute disease effect (no nutritional intake for more than five days) - to assign an overall risk of malnutrition (low, medium, or high) and an associated care plan.

Scope

The entry outlines MUST's components, its intended use across care settings, and the evidence for its validity and ease of use. It is a methodological reference topic and does not provide clinical instructions or thresholds for individual care.

Key concepts

• Body mass index score
• Unplanned weight loss score
• Acute disease effect score
• Overall risk categories (low, medium, high)
• Five-step screening process
• Cross-setting applicability (community, hospital, care home)
• Concurrent validity and inter-rater reliability

Mechanisms

MUST assigns points for three domains: a body mass index band, the percentage of unplanned weight loss over the preceding three to six months, and an acute disease effect when a patient is acutely ill and has had, or is likely to have, no nutritional intake for more than five days. The three scores are summed into an overall risk category, and each category is paired with a recommended action - from routine rescreening at low risk to referral and a care plan at high risk. The tool was designed to be quick and reproducible by a range of staff and to apply consistently across community, hospital, and care-home settings.

Clinical relevance

MUST is one of the most widely adopted nutrition screening tools in adult care and is recognized within screening guidelines and the GLIM framework as a route to identifying nutritional risk. As a reference topic, this entry describes how the tool is structured and validated and does not provide individualized scoring decisions or treatment advice.

Epidemiology

In Stratton and colleagues' validation across hospital outpatients and inpatients, MUST identified substantial proportions of adults at medium or high risk of malnutrition and showed concurrent validity against other tools together with good ease of use. Reported prevalence of risk varies with the population and setting screened.

History

MUST was developed by the Malnutrition Advisory Group of BAPEN to provide a single tool usable across care settings, addressing the proliferation of setting-specific instruments. Stratton and colleagues published validation evidence in 2004, and the tool was subsequently incorporated into national screening practice and referenced in nutrition screening guidance.

Debates

When body mass index or weight history is unavailable

MUST relies on measured or estimated body size and weight change, so alternative measurements and subjective criteria are needed when these cannot be obtained, which can affect comparability between assessments.

Key figures

• Marinos Elia
• Rebecca Stratton
• Mike Stroud

Seminal works

• stratton-2004
• kondrup-2003-guidelines

Frequently asked questions

What does MUST measure?

It combines body mass index, unplanned weight loss, and the effect of acute illness on intake into an overall low, medium, or high risk of malnutrition.

In which settings is MUST intended to be used?

MUST was designed to be applied consistently across community, hospital, and care-home settings by a range of staff, which is the source of its 'universal' name.