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🍎Medical Nutrition Therapy I

Malnutrition Screening Tools

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Why This Matters

Malnutrition screening is the critical first step in the Nutrition Care Process, and you're being tested on your ability to select the right tool for the right population in the right setting. These tools aren't interchangeable—each was designed with specific patient populations, clinical environments, and assessment parameters in mind. Understanding the underlying methodology of each tool (whether it relies on objective measures like BMI and lab values, subjective clinical judgment, or patient self-report) will help you answer exam questions about when to use which screening approach.

Beyond simple identification, these tools connect to bigger course concepts: sensitivity vs. specificity in screening, the difference between screening and assessment, and how disease severity impacts nutritional risk. When you encounter a case study asking which tool to use for a hospitalized oncology patient versus a community-dwelling older adult, you need to know the rationale behind each recommendation. Don't just memorize tool names and their acronyms—know what type of data each tool collects and why that matters for the population it serves.


Quick, Question-Based Screening Tools

These tools prioritize speed and simplicity, using just a few targeted questions to flag at-risk individuals. The underlying principle is that brief, focused questions about weight loss and appetite can effectively identify most patients needing further nutritional assessment.

Malnutrition Screening Tool (MST)

  • Two-question format—asks only about unintentional weight loss and appetite changes, making it one of the fastest tools available
  • Minimal training required for administration, allowing nurses, aides, or even clerical staff to conduct screening
  • High sensitivity means it effectively catches most at-risk patients, though some may be false positives requiring further assessment

Short Nutritional Assessment Questionnaire (SNAQ)

  • Patient self-administered—designed for outpatient settings where patients complete the questionnaire independently
  • Focuses on weight loss and appetite similar to MST, but formatted for patient comprehension rather than clinician administration
  • Initiates nutrition conversations by providing a structured starting point for discussing dietary interventions with ambulatory patients

Compare: MST vs. SNAQ—both use weight loss and appetite as key indicators, but MST is clinician-administered for inpatient efficiency while SNAQ is patient-completed for outpatient autonomy. If asked about screening in a busy clinic where staff time is limited, SNAQ is your answer.


Objective, Algorithm-Based Tools

These tools use measurable parameters like BMI, weight loss percentages, and disease factors to generate risk scores. The methodology here emphasizes reproducibility—different clinicians using the same data should reach the same conclusion.

Malnutrition Universal Screening Tool (MUST)

  • Three-step algorithm—combines BMI, unplanned weight loss percentage, and acute disease effect to calculate overall risk score
  • Clear action protocols accompany each risk level (low, medium, high), guiding clinicians on intervention intensity
  • Versatile across settings—validated for hospitals, community care, and long-term care facilities, making it one of the most widely adopted tools

Nutrition Risk Screening 2002 (NRS-2002)

  • Dual-component scoring—uniquely integrates nutritional status (BMI, weight loss, intake) with disease severity as separate scored categories
  • Hospital-specific design—developed specifically for acute care settings where illness severity significantly impacts nutritional needs
  • Age adjustment—adds one point for patients over 70, acknowledging increased vulnerability in older hospitalized adults

Nutritional Risk Index (NRI)

  • Laboratory-dependent—calculates risk using serum albumin and usual body weight, making it more objective but requiring blood work
  • Formula-based scoring: NRI=(1.519×serum albumin g/L)+(41.7×present weightusual weight)NRI = (1.519 \times \text{serum albumin g/L}) + (41.7 \times \frac{\text{present weight}}{\text{usual weight}})
  • Predictive of surgical outcomes—particularly useful for identifying patients at risk for postoperative complications related to malnutrition

Compare: MUST vs. NRS-2002—both generate numerical risk scores, but NRS-2002 explicitly weights disease severity while MUST considers acute disease as a binary yes/no factor. For hospitalized patients with significant illness burden, NRS-2002 may capture risk more precisely.


Comprehensive Clinical Assessment Tools

These tools go beyond screening to provide detailed nutritional evaluation through clinical judgment and physical examination. The methodology combines objective findings with clinician interpretation, requiring more training but yielding richer diagnostic information.

Subjective Global Assessment (SGA)

  • Clinical judgment-based—integrates medical history (weight change, intake, GI symptoms, functional capacity) with physical exam findings (muscle wasting, fat loss, edema)
  • Three-category rating—classifies patients as well-nourished (A), moderately malnourished (B), or severely malnourished (C)
  • Gold standard validity—considered highly reliable across settings, though requires trained clinicians to administer consistently

Mini Nutritional Assessment (MNA)

  • Geriatric-specific design—validated specifically for adults 65 years and older, addressing unique nutritional concerns in aging populations
  • Two-part structure—short-form screening (6 questions) can stand alone or trigger full assessment (18 questions) for comprehensive evaluation
  • Multidimensional approach—incorporates mobility, psychological stress, neuropsychological problems, and living situation beyond typical nutrition parameters

Compare: SGA vs. MNA—both provide comprehensive assessment rather than just screening, but MNA is population-specific (older adults) while SGA is generalizable across age groups. On an exam asking about a 78-year-old in long-term care, MNA is the targeted choice; for a 45-year-old surgical patient, SGA applies.


Patient-Centered and Specialty Tools

These tools incorporate patient self-report as a core component, recognizing that patients provide unique insight into their nutritional status and symptoms. The methodology values subjective experience alongside clinical observation, particularly important in populations with complex symptom burdens.

Patient-Generated Subjective Global Assessment (PG-SGA)

  • Patient-completed sections—patients report their own weight history, food intake, symptoms, and functional status before clinician review
  • Oncology gold standard—specifically validated for cancer patients and widely used in oncology and palliative care settings
  • Numerical scoring option—generates a score indicating urgency of nutrition intervention, facilitating triage in busy oncology clinics
  • Symptom checklist—captures nutrition-impacting symptoms like nausea, mouth sores, and taste changes common in cancer treatment

Compare: SGA vs. PG-SGA—PG-SGA evolved from SGA but shifts initial data collection to the patient and adds symptom assessment. For oncology patients experiencing treatment side effects, PG-SGA captures the full picture; standard SGA works for general medical populations.


Quick Reference Table

ConceptBest Examples
Rapid inpatient screeningMST, NRS-2002
Outpatient/self-administeredSNAQ, MNA short-form
Algorithm with clear action stepsMUST, NRS-2002
Requires laboratory valuesNRI (serum albumin)
Geriatric populationsMNA
Oncology/palliative carePG-SGA
Comprehensive clinical assessmentSGA, MNA full assessment
Incorporates disease severityNRS-2002, NRI

Self-Check Questions

  1. A 72-year-old patient is admitted to a long-term care facility. Which screening tool was specifically designed and validated for this population, and what non-nutritional factors does it assess?

  2. Compare MST and MUST: both are used in hospital settings, but how do their methodologies differ in terms of data collected and scoring approach?

  3. An oncology dietitian needs to assess a patient undergoing chemotherapy who reports severe nausea and taste changes. Which tool would best capture both nutritional status and treatment-related symptoms, and why?

  4. NRS-2002 and NRI both assess hospitalized patients, but they differ in one key requirement. What is it, and how might this affect which tool you select in a resource-limited setting?

  5. FRQ-style prompt: A hospital is implementing a new malnutrition screening protocol. Explain why you might choose MUST over SGA for initial screening, then describe when you would escalate to SGA for comprehensive assessment.