What is the MUST Tool and Why is it Essential?
The Malnutrition Universal Screening Tool (MUST) is a foundational tool in clinical nutrition, providing a standardized, systematic approach to identify adults who are malnourished, at risk of malnutrition, or obese. Developed by the Malnutrition Advisory Group of BAPEN, it is widely implemented in various healthcare settings, including hospitals, community clinics, and care homes. Its purpose is to efficiently and reliably screen patients, ensuring those at risk receive further, detailed assessment and appropriate nutritional care. The tool is not designed to diagnose specific vitamin or mineral deficiencies but to identify the overall risk of undernutrition. The successful and correct implementation of MUST has been shown to improve patient outcomes, reduce complications, and decrease healthcare costs associated with malnutrition.
The Five-Step MUST Screening Process
Implementing the MUST tool involves a simple yet robust five-step process that can be performed by any trained healthcare professional.
- Calculate BMI: This is the first step, involving measuring the patient's height and weight to calculate their Body Mass Index (BMI). A chart is used to assign a score based on the result. For non-ambulatory patients or those with severe physical deformities, alternative measurements like arm span or estimated height can be used.
- Assess Weight Loss: The second step involves determining the patient's unintentional weight loss percentage over the last three to six months. Scores are assigned based on the severity of the weight loss. This provides a crucial historical context for the patient's nutritional status.
- Evaluate Acute Disease Effect: The third step considers the presence of an acute disease and whether the patient has had, or is likely to have, little or no nutritional intake for more than five days. A score is assigned based on this evaluation.
- Determine Overall Risk Score: The scores from the first three steps are added together to get a total risk score. This score categorizes the patient into one of three risk levels: low, medium, or high.
- Develop Management Plan: Based on the total score, a management plan is developed. For low-risk patients, routine clinical care is recommended. Medium-risk patients require observation and monitoring of their dietary intake, while high-risk patients require immediate treatment, often including referral to a registered dietitian.
Limitations and Considerations for the MUST Tool
While highly effective, the MUST tool has certain limitations and requires careful interpretation in specific patient populations. It was originally developed for general adult populations and its interpretation may be complex for individuals with fluid disturbances, critical illness, or during pregnancy. For example, a patient with edema or fluid retention may have an artificially higher weight, masking true undernutrition. Furthermore, the tool's reliance on BMI can be misleading for very muscular individuals or older adults who have lost lean muscle mass but gained fat, as BMI doesn't differentiate between the two. In cases where a different or more detailed assessment is needed, other validated tools or a comprehensive nutritional assessment by a dietitian are recommended.
Comparison of Key Nutritional Assessment Tools
| Feature | Malnutrition Universal Screening Tool (MUST) | Mini Nutritional Assessment (MNA) | Subjective Global Assessment (SGA) |
|---|---|---|---|
| Primary Purpose | Universal screening for adults at risk of malnutrition and obesity. | Screening and assessment specifically for the elderly (65+). | Assessment for a wide range of hospitalized patients, including surgical and oncology patients. |
| Key Components | BMI, unintentional weight loss, and acute disease effect. | Questions on dietary intake, weight loss, mobility, stress, neuropsychological issues, and BMI. | Medical history (weight loss, intake change) and physical examination (fat loss, muscle wasting). |
| Target Population | General adult population across various healthcare settings. | Geriatric patients (65 years and older). | General adult hospital populations, widely adaptable. |
| Application | Quick and simple, can be used by any trained care provider. | Short-Form (MNA-SF) for screening, Long-Form for detailed assessment. | Requires trained rater for accurate physical examination. |
| Validation | Nationally recognized and validated tool. | Most validated tool for the elderly population. | Validated extensively, especially in surgical and cancer patient populations. |
| Diagnostic Focus | Risk identification to prompt further assessment. | Diagnosis of malnutrition or risk within the geriatric population. | Categorizes malnutrition severity (well-nourished, moderate, severe). |
The Role of Comprehensive Assessment
While screening tools like MUST are crucial for initial identification, a comprehensive nutritional assessment provides a deeper, more detailed evaluation. This process, often conducted by a registered dietitian, follows a systematic approach including:
- Anthropometric data: Detailed measurements of body size and shape, such as skinfold thickness and circumference measurements, to better estimate body composition.
- Biochemical analysis: Blood and urine tests to evaluate protein status (albumin, prealbumin), micronutrient levels, and other relevant markers of inflammation.
- Clinical evaluation: A thorough physical examination to identify signs of malnutrition, such as muscle wasting, loss of subcutaneous fat, or specific vitamin deficiency symptoms.
- Dietary assessment: A detailed history of food and nutrient intake, often using 24-hour recalls, food frequency questionnaires, or food diaries.
This multi-faceted approach ensures that a patient's nutritional status is fully understood, allowing for the most effective and personalized intervention plan. The MUST tool acts as an efficient gatekeeper, helping to prioritize which patients require this more in-depth assessment.
Conclusion: MUST is a Foundational First Step
The Malnutrition Universal Screening Tool (MUST) stands out as a vital and efficient first step in nutritional assessment for adults. Its simple, five-step process allows for widespread use by healthcare staff, ensuring that individuals at risk of malnutrition are quickly identified. While not a definitive diagnostic tool for all nutritional problems, its ability to flag patients for further, more comprehensive assessment—including dietary history, biochemical tests, and physical examination—makes it indispensable. The effective deployment of the MUST tool leads to earlier interventions, improved patient care, and ultimately, better clinical outcomes, making it a true 'must' in modern healthcare.
British Association for Parenteral and Enteral Nutrition (BAPEN)
Glossary
- Malnutrition: A condition that results from a deficiency, excess, or imbalance of energy, protein, and other nutrients, leading to adverse effects on body composition, function, or clinical outcome.
- Undernutrition: A specific form of malnutrition resulting from insufficient intake of energy and nutrients.
- Obesity: A state of overnutrition characterized by an excessive accumulation of body fat.
- Anthropometry: The scientific study of the measurements and proportions of the human body, including height, weight, and circumferences.
- BMI (Body Mass Index): A measure of body fat based on height and weight that applies to adult men and women.
- Registered Dietitian (RD): A food and nutrition expert who has met specific academic and professional requirements and can provide medical nutrition therapy.
