Malnutrition: muscle wasting, inflammation, RDW, and their relation with adverse outcomes.

Objective: The objective of the study was to explore red cell distribution width (RDW) as a surrogate marker of inflammation, alone and in conjunction with muscle wasting to predict malnutrition-related adverse outcomes.

Methods: This was a single-center observational study including adult hospitalized patients. Demographic variables, malnutrition criteria, and RDW were captured within 24 hours of hospital admission. Correlation tests and regression models were performed between these variables (RDW and muscle wasting) and adverse outcomes (in-hospital mortality and unplanned transfer to critical care areas (CCA).

Results: Five hundred and forty-five patients were included in the final analysis. Muscle wasting showed an independent association with adverse outcomes in every regression model tested. RDW alone showed fair predictive performance for both outcomes' significance and the adjusted model with muscle wasting showed association only for unplanned transfer to CCA.

Conclusion: RDW did not improve the prediction of adverse outcomes compared to muscle wasting assessed by physical examination and simple indexes for acute and chronic inflammation. Malnourished patients presented higher RDW values showing a possible metabolic profile (higher inflammation and lower muscle). It is still unknown whether nutrition support can influence RDW value over time as a response marker or if RDW can predict who may benefit the most from nutritional support.