Navigating complexity: The challenge of reaching consensus on the diagnosis of malnutrition in patients with obesity via a modified delphi study

Background & aim: Diagnosing (disease-related) malnutrition in patients with obesity is challenging due to the complex interplay between excess body weight and physiological changes associated with illness and inadequate dietary intake, factors often overlooked in clinical assessments. Current global definitions of malnutrition do not adequately account for the distinctive characteristics of patients with obesity. This study aimed to develop a working definition of malnutrition in this population. Methods: A modified three-round Delphi method was conducted between March and July 2024, involving 25 experts to achieve consensus on diagnosing malnutrition in obesity. In Round 1, participants evaluated 45 statements using a 5-point Likert scale. Feedback from this round guided revisions for Round 2, which focused on the Global Leadership Initiative on Malnutrition (GLIM) criteria and introduced nine revised statements. Round 3 further refined these statements, with the final consensus assessed using a binary agree/disagree scale. A threshold of ≥70 % agreement was set to define consensus in all rounds, with statements not meeting this threshold left undecided. Results: Participation rates were 88 % (n = 22) in Round 1, 77 % (n = 17) in Round 2, and 50 % (n = 11) in Round 3. Of the 45 statements assessed in Round 1, 11 were accepted, 32 were undecided, and two were rejected. Round 2 introduced nine revised statements, of which seven were accepted and two remained undecided. In Round 3, nine statements were assessed, of which six were accepted, and three remained undecided. Consensus supported adopting the GLIM criteria as the foundation for the working definition. However, thresholds for weight loss and muscle mass and the relevance of functional parameters remained unresolved. C-reactive protein thresholds were agreed upon, but their relevance was debated due to the challenges in interpreting chronic low-grade inflammation in obesity. Participants emphasised the importance of assessing dietary quality and quantity, recommending dietitian involvement for improved accuracy. Conclusion: Although a working definition for diagnosing malnutrition in patients with obesity was not achieved, this study lays a crucial foundation for further research. Key areas for future investigation include refining and validating parameters related to involuntary weight loss, muscle mass, inflammatory markers and dietary intake.