Defining malnutrition and its severity has always been problematic. The centuries-old traditional concept of malnutrition has been a chronic state of nutritional deprivation resulting in a constellation of characteristic clinical findings in four categories: causation, physical findings, body mass composition, and biomarkers.
In 2012, the Academy of Nutrition and Dietetics and the American Society for Parenteral and Enteral Nutrition (ASPEN) published what is known as the ASPEN criteria for the diagnosis of malnutrition, defining it as “undernutrition” (11. White JV, Guenter P, Jensen G, Malone A, Schofield M; Academy of Nutrition and Dietetics Malnutrition Work Group. Consensus statement of the Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition: characteristics recommended for the identification and documentation of adult malnutrition (undernutrition). J Acad Nutr Diet. 2012;112:730-8. [PMID: 22709779]). This definition has become widely accepted in the nutrition community, but unfortunately, the ASPEN criteria have some inconsistencies, operational deficiencies, and regulatory vulnerabilities.
On Sept. 2, 2018, a new global consensus definition of malnutrition was published by the Global Leadership Initiative on Malnutrition (GLIM) (22. Jensen GL, Cederholm T, Correia MITD, Gonzalez MC, Fukushima R, Higashiguchi T, et al. GLIM criteria for the diagnosis of malnutrition: A consensus report from the global clinical nutrition community. JPEN J Parenter Enteral Nutr. 2018. [PMID: 30175461]). The stated purpose of GLIM is to reach a global consensus on the identification and endorsement of criteria for the diagnosis of malnutrition in clinical settings. GLIM included representatives from ASPEN, the European Society for Clinical Nutrition and Metabolism, Latin American Nutritional Federation, and Parenteral and Enteral Nutrition Society of Asia.
The GLIM definition of malnutrition is based on five diagnostic criteria (see Table 1), three of which are phenotypic (clinical findings) and two of which are etiologic (causes). The diagnosis of malnutrition requires at least one phenotypic criterion and one etiologic criterion. Severity of malnutrition is based on the phenotypic criterion meeting the highest level of severity (see Table 2).
The GLIM criteria offer some advantages over the 2012 ASPEN criteria. While the ASPEN criteria are effective for diagnosing malnutrition, they are less useful for defining severe malnutrition. The GLIM criteria are less subjective and more clinically intuitive, and they include parameters that are more consistent with the traditional concepts of nonsevere and severe malnutrition.
The GLIM etiology criteria for acute disease/injury include confirmation of severe systemic inflammation, in contrast to ASPEN. This is a much-needed provision that incorporates recent research showing the central role of systemic inflammation in the development of malnutrition. Biomarkers are recommended by GLIM to confirm chronic or severe systemic inflammation. C-reactive protein (CRP) is preferred, but low albumin/prealbumin levels are also included. While not specifically mentioned by GLIM, systemic inflammatory response syndrome (SIRS) criteria could also be used to identify systemic inflammation.
Applying the GLIM criteria for body mass index (BMI) could be problematic in the United States. A sizable proportion of the population is obese to begin with, so some patients with malnutrition can be expected to have a BMI above 22 kg/m2. A BMI below 20 or 22 kg/m2 (depending on patient age) may not work as a criterion for malnutrition when the CDC definition of normal is 18.5 kg/m2 to 24.9 kg/m2. Consideration should be given to modifying the GLIM criterion on BMI to under 18.5 kg/m2 for moderate (stage 1) malnutrition and under 16 kg/m2 for severe (stage 2) malnutrition in order to be more consistent with clinical expectations and for compliance purposes.
ICD-10-CM codes for malnutrition are shown in Table 3. Codes E40 (kwashiorkor), E41 (nutritional marasmus), and E42 (marasmic kwashiorkor) are reserved for malnutrition specifically related to these conditions, which are extremely rare in the United States and so should be infrequently coded. GLIM identifies only stage 1 (moderate) and stage 2 (severe) malnutrition. Malnutrition stage is not codeable, so the severity of malnutrition should be specifically documented as mild, moderate, or severe.