Prognostic and associative significance of malnutrition in sarcopenia: a systematic review and meta-analysis

Malnutrition is a common phenomenon, particularly in those at an increased risk of muscle mass and function losses. In this systematic review and meta-analysis, we aimed to explore the association of malnutrition with sarcopenia in middle-aged and older adults and the prognostic association of malnutrition and sarcopenia compared with sarcopenia alone on all-cause mortality. PubMed, Scopus, Web of Science, and Cochrane Library were searched from inception until January 2024. A meta-analysis using a random-effect model was employed, utilizing the Mini Nutritional Assessment malnutrition tool as a continuous and categorical variable. The study protocol was registered in the International Prospective Register of Systematic Reviews (CRD42024501521). Malnutrition was significantly associated with a greater risk of sarcopenia [continuous: k = 12, odds ratio (OR): 1.38, 95% confidence interval (CI): 1.18, 1.61, I2 = 94.8%, P < 0.01; categorical: k = 37, OR: 2.99, 95% CI: 2.26, 3.96, I2 = 78.3%, P < 0.01]. Sarcopenia and malnutrition were associated with a higher risk of mortality compared with sarcopenia alone (k = 5, hazard ratio: 4.04, 95% CI: 1.36, 11.94, I2 = 92.8%, P < 0.01). Metaregression showed age, sex, and number of adjustments did not explain heterogeneity among studies. The included studies had a moderate risk of bias. Malnutrition is associated with higher odds of sarcopenia and their combined presence is a better predictor of all-cause mortality compared with sarcopenia alone, further highlighting the importance of applying interventions to counteract these two closely related phenomena.