The Core Principles of Malnutrition Screening
Malnutrition is a complex condition caused by inadequate or excessive nutrient intake that results in adverse health outcomes. It is often overlooked in clinical settings, but a simple screening process can quickly identify those at risk. A screening tool is a rapid, validated instrument used to determine the probability of an individual being malnourished or at risk of malnutrition. It is a triage system, not a diagnostic one. If a patient is identified as high-risk, a more comprehensive nutritional assessment is required, usually performed by a dietitian. The goal of screening is to ensure timely and effective nutritional intervention, which has been shown to reduce complications, shorten hospital stays, and lower mortality rates.
The Importance of Routine Screening
Routine screening is vital across all care settings, including hospitals, community clinics, and residential aged care. Screening should occur upon admission and at regular intervals thereafter, especially in long-term care. Key indicators for screening include recent, unintentional weight loss, reduced appetite, or a prolonged period of poor nutritional intake.
A Guide to the Malnutrition Universal Screening Tool (MUST)
The Malnutrition Universal Screening Tool (MUST) is one of the most widely recognized and validated tools for use with adults. It involves five simple steps to calculate a risk score.
Step 1: Calculate the BMI Score
Measure the patient's weight and height to calculate their Body Mass Index (BMI). If a patient's height cannot be measured, alternative methods, such as ulna length, can be used.
- BMI >20 (or >30 for obese): Score 0
- BMI 18.5–20.0: Score 1
- BMI <18.5: Score 2
Step 2: Determine Unintentional Weight Loss
Ask the patient or a caregiver about any unplanned weight loss over the past 3 to 6 months. Reviewing medical records can also provide historical weight data.
- Unintentional weight loss <5%: Score 0
- Unintentional weight loss 5–10%: Score 1
- Unintentional weight loss >10%: Score 2
Step 3: Identify the Acute Disease Effect
Determine if the patient is acutely ill and whether there has been, or is likely to be, no nutritional intake for more than 5 days. Acute illness can significantly increase a patient's nutritional needs.
- No acute illness: Score 0
- Acute illness with no nutritional intake for >5 days: Score 2
Step 4: Add the Scores Together
Sum the scores from the previous three steps. The total gives the overall risk category for malnutrition.
- Score 0: Low risk
- Score 1: Medium risk
- Score 2 or more: High risk
Step 5: Implement the Care Plan
Based on the overall risk score, follow the appropriate management plan.
- Low Risk: Continue routine clinical care and rescreen as per local policy (e.g., weekly for inpatients, monthly for care homes, or annually in the community).
- Medium Risk: Observe the patient's dietary intake for 3 days. If intake is inadequate, improve nutritional support with fortified foods or oral nutritional supplements. Monitor and rescreen regularly.
- High Risk: Refer immediately to a registered dietitian or nutritional support team. A comprehensive nutritional assessment and a tailored care plan are required, with frequent monitoring and review.
Other Malnutrition Screening Tools
While MUST is a general-purpose tool, others are more specialized for specific populations or settings:
- Malnutrition Screening Tool (MST): A very simple two-question tool ideal for older adults and community settings. It assesses recent weight loss and decreased appetite.
- Mini Nutritional Assessment (MNA): Used for geriatric patients (65+) and includes both a short-form (MNA-SF) and a full assessment. It considers factors like food intake, mobility, psychological stress, and BMI or calf circumference.
- Nutritional Risk Screening (NRS-2002): A validated tool for hospitalized patients that uses a pre-screening questionnaire before proceeding to a more detailed scoring system that incorporates the severity of the disease.
Comparison of Malnutrition Screening Tools
| Feature | MUST | MST | MNA-SF | NRS-2002 |
|---|---|---|---|---|
| Target Population | General adult population | General adult population, simple format | Geriatric population (>65) | Hospitalized adults |
| Number of Steps | 5 | 2 | 6-question screening | Pre-screening + 4-item scoring |
| Scoring | Low (0), Medium (1), High (≥2) | Low Risk (0-1), At Risk (≥2) | Normal (12-14), At Risk (8-11), Malnourished (0-7) | No Risk (<3), At Risk (≥3) |
| Key Components | BMI, weight loss, acute disease | Weight loss, appetite | Food intake, weight loss, mobility, stress, BMI | BMI, weight loss, food intake, disease severity, age |
| Setting | Hospital, community, care homes | Hospital, community, aged care | Aged care, community, hospital | Hospital |
| Ease of Use | Moderate | Very Easy | Easy | Moderate |
Conclusion
Understanding how to use a malnutrition screening tool is an indispensable skill for healthcare professionals. These tools provide a systematic and reliable method for identifying individuals at risk, allowing for early and targeted nutritional support. Whether utilizing the comprehensive MUST for a hospital patient or the simpler MST for an elderly person in the community, the principle remains the same: a quick and validated screening process is the first critical step toward improving a patient's nutritional status and overall health outcomes. By adhering to screening protocols and following through with appropriate management plans, care providers can effectively mitigate the adverse effects of malnutrition. For further guidance and resources, consult authoritative bodies like the British Association for Parenteral and Enteral Nutrition (BAPEN).
