The overlap of malnutrition, sarcopenia, cachexia, and frailty in older adults

Background: Guidelines recommend the assessment of malnutrition, sarcopenia, cachexia, and frailty in vulnerable older adults; however, there is potentially high diagnostic overlap of these syndromes leading to patient burden and resource waste.

Aim: To explore the theoretical and empirical evidence of diagnostic overlap of malnutrition, sarcopenia, cachexia, and frailty in older adults.

Methods: A scoping review was performed (July 2023) to identify: (1) guidelines which provided diagnostic definitions for protein-energy malnutrition, sarcopenia, cachexia, and frailty, or (2) original research studies that measured two or more of these syndromes in older adults. Theoretical definitions and diagnostic criteria were mapped. Percent overlap of diagnosed syndromes were extracted.

Results: ‘Loss of lean mass’ was a defining concept in all four syndromes. ‘Inflammation’ and ‘inadequate energy and protein intake’ were aetiological factors in the diagnostic definitions of disease-related malnutrition, secondary sarcopenia, and all types of frailty and cachexia. Ten constructs were identified across the recommended assessment tools for each syndrome: 40% of constructs were assessed in all four tools (e.g., muscle mass) and 40% in three tools (e.g., fatigue). One study was identified which measured diagnostic overlap. In acute care patients, 11% had two syndromes, 12% had three syndromes, and 8% had all four syndromes. 53% of the malnourished patients had all four syndromes (93% had cachexia; 80% had sarcopenia).

Conclusion: There is a high theoretical overlap of malnutrition, sarcopenia, cachexia, and frailty in older adults. Empirical evidence is lacking to support the scaling back of diagnostic assessments despite the potential for decreased burden.