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Table 2 Selected malnutrition screening and assessment tools and limitations to their application in patients with obesity

From: Obesity and critical care nutrition: current practice gaps and directions for future research

Screening Attributes/benefits Limitations
Malnutrition screening tool (MST) Risk is calculated based on whether the patient lost weight without trying, the amount of weight loss, and poor appetite, so it is quick and straightforward to administer Does not consider body composition changes, only recent weight loss
  Does not rely on low BMI as an indicator Requires self-reported data from the patient, so not ideal for those who are unable to communicate
  Endorsed by AND. Received a “good/strong” rating compared with other tools that only received a fair evidence grade; recommended regardless of patient age or practice setting [34]  
Malnutrition universal screening tool (MUST) Risk is calculated based on BMI, unplanned weight loss, and acute disease effect, therefore quick and straightforward Relies on BMI without considering body composition changes; not sensitive for patients with obesity [35]
   Weight loss is described as “unplanned;” may have been “planned” by patient through unhealthy practices or secondary to acute illness that may not be captured
   Requires patient-reported data; not ideal for those who are unable to communicate
   Not specific to critical illness; lower prognostic value in predicting 28-day mortality than the modified NUTrition Risk in the Critically ill (mNUTRIC) score [36]
Modified NUTrition risk in the critically ill (mNUTRIC) score Risk based on age, comorbidities, Acute Physiology and Chronic Health Evaluation II score, Sequential Organ Failure Assessment score, days in hospital before ICU admission; interleukin-6 may or may not be added Intended to identify patients who would most benefit from nutrition support, not necessarily those with malnutrition
  Does not rely on low BMI as an indicator More difficult to calculate
  Does not require self-reported data from the patient  
  Familiar in a range of practice settings  
  Endorsed by 2016 ASPEN/SCCM guidelines [23]  
Nutrition risk score 2002 Risk based on weight loss or low BMI, reduced food intake, and severity of disease, therefore quick and straightforward Intended to identify patients who would most benefit from nutrition therapy, not necessarily those with malnutrition
  Endorsed by 2016 ASPEN/SCCM guidelines [24] Relies on BMI and weight change without considering body composition changes
Assessment   
Nutrition-focused physical exam (NFPE) AND and ASPEN recommend six criteria be assessed to identify malnutrition: weight loss, reduction in dietary intake, subcutaneous fat loss, loss of muscle mass, fluid accumulation, and declining functional status. If two or more are present, a nutrition diagnosis of malnutrition is supported [37] Requires training/expertise
  Does not rely on low BMI as an indicator May be more challenging if a baseline NFPE is not available to compare to
  AND and ASPEN endorse the NFPE to collect certain criteria (loss of fat and muscle mass and edema) for the nutrition diagnosis of malnutrition [37] NFPE may be more difficult in patients with generalized edema
  The NFPE may also be modified to assess for clinical signs of micronutrient deficiencies Excess adiposity may present barriers to accurately assessing muscle or fat mass loss
Subjective global assessment (SGA) and patient-generated SGA Assessment criteria include weight, weight history, food intake, symptoms that may impact dietary intake, activities/function, comorbidities, metabolic factors, and physical exam Requires training because as indicated, it is subjective
  Does not rely on low BMI as an indicator May rely on patient-reported data; not ideal for those who are unable to communicate
  Based on clinical reasoning; has been used in various settings, including ICU, with good predictivity for complications and mortality Excess adiposity may present barriers to accurately assessing muscle or fat mass
Global Leadership Initiative on Malnutrition (GLIM) Assessment criteria include factors that may contribute to etiology of malnutrition (inflammation and reduced dietary intake or assimilation) and phenotypic criteria (non-volitional weight loss, low BMI, and reduced muscle mass) [38] Low BMI has been reported to be one of the most often used criterion [39]; therefore, utility in patients with obesity is unclear
  Muscle mass may be assessed through “dual-energy absorptiometry (DXA) or corresponding standards using other body composition methods like bioelectrical impedance analysis (BIA), CT, or MRI. When not available or by regional preference, physical examination or standard anthropometric measures like mid-arm muscle or calf circumferences may be used.” [38] Weight loss is described as “non-volitional;” therefore, weight loss that may have been “volitional” by the patient but achieved through unhealthy practices or secondary to acute illness may not be captured
   The preferred measurements of muscle mass–DXA, CT, and MRI–may not be feasible or available for many ICU patients
Anthropometry Inexpensive Influenced by edema and assessor technique
  Easily conducted in clinical setting Patient positioning may make accurate assessment challenging
   Cutoff values do not consider obesity
   Unable to differentiate adipose from muscle tissue
Bioimpedance Easily conducted in clinical setting Influenced by hydration
   Limited in assessing those with obesity
Ultrasonography Easily conducted in clinical setting, assesses muscle mass Requires expertise and training
   May be difficult to assess muscle according to the amount of adiposity
Tomography and magnetic resonance Provides detailed information on muscle mass Expensive
   Inconvenient methods
   May not be feasible or available for many ICU patients
Biochemical parameters (albumin, transthyretin) Commonly available Influenced by hydration and inflammation and therefore, not an accurate measure of nutrition status in many ICU patients
  Inexpensive  
Dynamometry Assesses muscle functionality Not feasible in many ICU patients due to sedation and neuromuscular blockade
   May be less informative if a baseline measurement is not available to compare to
  1. AND Academy of Nutrition and Dietetics, ASPEN American Society for Parenteral and Enteral Nutrition, BMI body mass index, CT computed tomography, ICU intensive care unit, MRI magnetic resonance imaging