How to Screen for Malnutrition
Use the Malnutrition Screening Tool (MST) for all adult patients (≥18 years) regardless of age, setting, diagnosis, or condition. 1
Recommended Screening Tool
The Norwegian Directorate of Health, using GRADE and DECIDE methodologies with systematic review evidence, specifically recommends MST as the single standardized tool for malnutrition screening across all healthcare settings 1. This recommendation emerged from a rigorous consensus process that evaluated four major screening tools (MST, MUST, NRS-2002, and MNA) and ranked MST highest based on:
- Low complexity (rated 5/5 - the highest priority criterion)
- Superior generalizability across ages, settings, and diagnoses
- Focus on key parameters: changes in food intake and weight loss (both rated 4/5), which were prioritized over BMI alone (rated 3/5)
- High sensitivity (78%) for detecting malnutrition 2
Alternative Validated Tools
While MST is the top recommendation, other validated options include:
- MUST (Malnutrition Universal Screening Tool): Demonstrated highest overall accuracy with 80% sensitivity, 74.7% specificity, and 44.4% positive predictive value in hospitalized patients 3
- NRS-2002: Comparable specificity (88%) but lower sensitivity (67%) 2
- MNA-SF (Mini Nutritional Assessment Short Form): Particularly useful for patients >65 years with 94.4% sensitivity, though lower specificity (39%) 3
When to Screen
Screen systematically and periodically:
- On admission to hospital or residential care facilities
- For outpatients with chronic conditions
- Within 48 hours of hospital admission 3
Two-Step Process
Step 1: Screening - Use a validated screening tool (MST preferred) to identify patients "at risk" 4, 5
Step 2: Assessment - For positive screens, conduct comprehensive nutritional assessment including:
- Health history and clinical examination
- Dietary history
- Anthropometric measurements
- Body composition evaluation when possible
- Functional assessment 4
Important Caveats
- All screening tools have limitations: Even the best tools show positive and negative likelihood ratios indicating only "minimal effect rating" for detecting malnutrition 2, meaning some malnourished patients will be missed
- Screening alone is insufficient: A positive screen must be followed by formal nutritional assessment and diagnosis using established criteria (ESPEN or GLIM) 6, 5
- BMI can be misleading: Cancer patients and others may have normal or elevated BMI despite significant malnutrition 7
- Standardization matters: Using multiple different screening tools creates miscommunication between healthcare providers, complicates research comparisons, and poses patient safety risks 1
Implementation Considerations
The screening tool must be:
- Simple and quick to perform in daily clinical practice
- Applicable across all adult ages without age-specific modifications
- Usable in different institutional settings (inpatient, outpatient, home care)
- Validated for different diagnostic groups 1
For positive screens, ensure systematic nutritional assessment, individual nutrition planning, and documentation/communication of nutritional information follow the screening 1.