Malnutrition and Muscle Loss Mediate the Association between NT-proBNP and Mortality in Hospitalized Older Adults

Abstract

Abstract Background & Aims The purpose of this study was to assess the association between N-terminal prohormone of type B natriuretic peptide (NT-proBNP) and long-term mortality in hospitalized oldest-old adults and to explore the mediating role of malnutrition and muscle loss. Methods This prospective cohort study was conducted among 360 hospitalized patients ≥ 80 years of age (median age 87 [IQR 84–90] years, 24.4% women) in the Department of Geriatrics. The Geriatric Nutritional Risk Index (GNRI) and Mini Nutritional Assessment Short Form (MNA-SF) were used for nutritional assessment, while calf circumference was used as a measure of muscle mass. A Cox proportional hazard model was used to assess the relationship between NT-proBNP levels and mortality. Mediation analysis was used to explore the mediating effects of malnutrition and muscle loss. Results The median follow-up was 4.1 years with 159 (44.1%) deaths. Mortality risk increased by 32% per 2-fold increase in NT-proBNP levels (full adjusted hazard ratio: 1.32 [95% CI, 1.20–1.46]). A mediation analysis showed that a lower GNRI score and decreased calf circumference mediated the effects of high NT-proBNP and mortality risk, with an estimated relative effect size of 28.9%, while MNA-SF and calf circumference mediated the effect, with an estimated relative effect size of 25.3%. Conclusions NT-proBNP levels were associated with long-term mortality in hospitalized older patients. Moreover, the detrimental effects of NT-proBNP on survival were partly mediated by malnutrition and muscle loss.