Decreased intake or assimilation of nutrients will result in classic malnutrition, eg, undernutrition, but there is growing understanding that disease-associated inflammatory and other mechanisms may also contribute to malnutrition (ie, undernutrition).1-3 Although malnutrition is a global concern associated with excess morbidity, mortality, and cost, there has been an unfortunate lack of consensus on diagnostic criteria for application in clinical settings. No single existing approach has gained widespread global acceptance,1,4-8 making it difficult to compare findings across regions throughout the world or even between hospitals within regions. There is also misalignment of existing diagnosis coding protocols of the International Classification of Diseases, 10th Revision (http://www.who.int/classifications/icd/en/) with recent advances in clinical practice so that reimbursement denials for consultation are growing, and there is widespread confusion among practitioners. Therefore, it is an urgent priority to establish a global consensus regarding core criteria for the diagnosis of malnutrition in diverse clinical care settings. This article presents an overview of our recent consensus effort jointly published in the Journal of Parenteral and Enteral Nutrition9 and Clinical Nutrition.10 Please see the original articles for additional details and citations. For this consensus, our focus is on adults and malnutrition (ie, undernutrition). A similar process for children is a future priority.

CONSENSUS DEVELOPMENT

At the 2016 ASPEN meeting, the Global Leadership Initiative on Malnutrition (GLIM) was conceived to include a core leadership committee with 2 representatives from each of the participating global clinical nutrition societies: American Society for Parenteral and Enteral Nutrition (http://www.nutritioncare.org), European Society for Clinical Nutrition and Metabolism (ESPEN)(http://www.espen.org), Federacion Latinoamericana de Terapia Nutricional, Nutricion Clinica y Metabolis-mmo (FELANPE) (http://www.felanpeweb.org), and Parenteral and Enteral Nutrition Society of Asia (PENSA) (http://www.pensa-online.org) (11). An additional 27 participants were invited to comprise a larger supporting working group that brought additional global diversity and expertise to the consensus effort. There was agreement to develop a simple approach to malnutrition diagnosis using clinically relevant diagnostic criteria that are appropriate for application by all healthcare professionals.

Consensus was secured over the course of GLIM meetings held at the ESPEN and American Society for Parenteral and Enteral Nutrition meetings from 2016 to 2018.9,10,12,13 There was strong consensus that the first step is malnutrition risk screening to identify "at risk" status by the use of any validated screening tool.14-16 When "at risk" status is identified, then further assessment for diagnosis and severity grading should be conducted. A comprehensive survey of existing approaches used in screening and assessment of malnutrition was therefore performed (Table 1). A ballot was conducted whereby GLIM participants ranked criteria identified by the survey. An overwhelming majority of GLIM participants selected the following core criteria.

TABLE 1 Survey of Existing Approaches Used in Screening and Assessment of Malnutrition and Cachexia

PHENOTYPIC CRITERIA

* Weight Loss

There was strong GLIM consensus for the inclusion of weight loss as a phenotypic criterion. Validity is well established.

* Low Body Mass Index

Because low body mass index (BMI) is not common among North American adults, it has not been widely adopted as a clinical malnutrition indicator in that region. However, much of the world currently makes use of BMI as a criterion, so this iteration of the GLIM consensus includes low BMI.

* Reduced Muscle Mass

Reduced muscle mass is a criterion with strong supporting evidence. The Global Leadership Initiative on Malnutrition recommends measurement using validated body composition measures such as dual-energy absorptiometry, bioelectrical impedance, ultrasound, computed tomography, or magnetic resonance imaging. Because these methods are still not widely available throughout the globe, physical examination or anthropometric measures of calf or arm muscle circumference are included as suitable alternatives. Assessment of muscle function using grip strength or other validated procedures is suggested as a supportive measure (Tables 2 and 3). However, such measures should be performed concurrently for the assessment of sarcopenia.20

TABLE 2 Phenotypic and Etiologic Criteria for the Diagnosis of Malnutrition

TABLE 3 Thresholds for Severity Grading of Malnutrition Into Stage 1 (Moderate) and Stage 2 (Severe) Malnutrition

ETIOLOGIC CRITERIA

* Reduced Food Intake or Assimilation

Reduced food intake or assimilation was selected by GLIM as a well-validated malnutrition criterion. Poor oral health, medication adverse effects, depression, gastrointestinal complaints, anorexia, and inadequate nutrition support are typical causes. Gastrointestinal disorders of malabsorption, motility, and obstruction are also associated with reduced assimilation of food/nutrients. Supportive indicators include gastrointestinal complaints such as dysphagia, nausea, vomiting, diarrhea, constipation, and abdominal pain.

* Disease Burden/Inflammation

Disease burden/inflammation is a widely accepted etiologic criterion for malnutrition that has been incorporated into the GLIM construct. Although severe inflammation is often easy to recognize, clinical judgment may be necessary to recognize that of lesser degree. Laboratory indicators such as serum C-reactive protein can serve as supportive proxy measures of inflammation.

APPROACH TO MALNUTRITION DIAGNOSIS, SEVERITY GRADING, AND CLASSIFICATION

The Global Leadership Initiative on Malnutrition consensus designates weight loss, reduced BMI, and reduced muscle mass as phenotypic criteria, and reduced food intake/assimilation and disease burden/inflammation as etiologic criteria (Table 2 and Figure). The Global Leadership Initiative on Malnutrition proposes that at least 1 phenotypic criterion and 1 etiologic criterion be required for malnutrition diagnosis. Review of existing approaches used in screening and assessment served to guide selection of threshold values for the consensus diagnostic criteria and for severity grading (Table 3). Although only the phenotypic criteria are used for severity grading, the inclusion of the etiologic criteria for malnutrition diagnosis helps to identify appropriate interventions and anticipated outcomes. An etiology-based diagnosis scheme consistent with other recent guideline initiatives1,2 is endorsed by GLIM. Diagnosis options include malnutrition related to chronic disease with inflammation, chronic disease with minimal or no perceived inflammation, acute disease or injury with severe inflammation, and starvation including hunger/food shortage associated with socioeconomic or environmental factors.

FIGURE 1. The Global Leadership Initiative on Malnutrition diagnostic scheme for screening, assessment, diagnosis and grading of malnutrition. Figure reprinted with permission from Wiley (Jensen et al

WHERE DO WE GO FROM HERE?

GLIM promotes adoption of global consensus criteria so that malnutrition prevalence, interventions, and outcomes may be evaluated across the globe. A universal "language" of malnutrition will support the development of global standards of care to promote improved outcomes. Strong consensus endorsed core phenotypic and etiologic criteria for the diagnosis of malnutrition that are already in widespread use across the globe. Therefore, these criteria may be readily used with other approaches and additional criteria of regional preference. The consensus criteria were chosen for their simplicity and ready use by clinicians and other health practitioners using tools and methods that are generally available. The proposed approach is not intended to comprise comprehensive nutrition assessment, but it will provide a malnutrition diagnosis that may be complemented by more comprehensive assessments when individualized care and treatment plans are desired. Depending upon regional preferences and availability, it is recommended that consultation of skilled nutrition practitioners like dietitians be considered for comprehensive assessment.

The recommended GLIM approach encompasses both phenotypic and etiologic criteria for the diagnosis of malnutrition but uses only phenotypic criteria cut-points for severity grading. In order to better guide appropriate interventions and expected outcomes, etiology has been widely accepted as a diagnostic and guidance criterion by the clinical nutrition community (1,8). For example, the presence of a robust disease-associated inflammatory response will impact upon treatment selection and the outcome that may be anticipated. However, underlying etiology has not generally been included among criteria supporting the diagnosis of medical conditions in the ICD construct. The GLIM approach includes diagnostic criteria that address the spectrum of malnourished body morphologies - underweight, normal or obese. In healthcare settings it is increasingly common to confront malnutrition in overweight and obese persons that suffer undernutrition etiologies similar to their under or normal weight counterparts.

Optimal care requires appropriate malnutrition diagnosis and intervention, so we suggest that the GLIM consensus criteria should also be used to diagnose malnutrition in persons with overlap syndromes like sarcopenia, cachexia, and frailty. Since inflammatory mediators and other mechanisms besides malnutrition contribute to these overlap syndromes, it is also clear that approaches likely to benefit these syndromes will require additional interventions beyond nutrition, like pharmacological agents and exercise.

Going forward GLIM seeks to promote dissemination, implementation, validation testing, and feedback. Early testing will target existing databases with a longer-term goal of creating prospective databases across the globe comprised of the consensus core variables. It is anticipated that the consensus criteria will evolve through regular adaptations as new methodologies and evidence emerge. The Global Leadership Initiative on Malnutrition therefore proposes reevaluation every 3 to 5 years. In relation to the International Classification of Diseases revision process (ICD-11), GLIM will also share the proposed consensus approach with the World Health Organization. This is a particularly high priority because this classification scheme guides clinical diagnosis and reimbursement across the globe.

REFERENCES