Risk of malnutrition is a predictor of post-operative delirium: retrospective study in hip fracture patients

Background and aims. Delirium represents a common and often misdiagnosed complication of major surgical procedures in the elderly. It is associated with poor clinical and functional outcomes, including higher mortality rates. Because post-operative delirium (POD) is potentially preventable, it is crucial to identify patients at higher risk to develop it. Malnutrition and delirium are highly prevalent in the elderly, but studies exploring the relationship between malnutrition and incidence of POD after hip fracture (HF) surgery are lacking. Methods. We included all HF patients admitted to the Orthogeriatric Unit of San Gerardo University Hospital in the period 2011-2014, administering the Mini Nutritional Assessment-Short Form (MNA-SF) to estimate the risk of malnutrition. From a cohort of 273 patients, we compared two groups: 167 patients malnourished or at risk of malnutrition (MNA-SF<12, group 1), and 106 non-malnourished (MNA-SF≥12, group 2). We performed a multivariate logistic regression to assess the relationship between risk of malnutrition and the incidence of POD. Results. POD was prevalent in group 1 than group 2 (45.5% vs. 14.1%, p<0.001). The regression analysis, adjusting for different confounders, revealed that the only independent predictors of POD were MMSE<24 (OR=4.3, p<0.001) and MNA-SF<12 (OR=2.9, p=0.006). Conclusions. MNA-SF is a short and user-friendly tool to assess the risk of malnutrition in hospitalized elderly patients, and a score <12 is an independent predictor of post-operative delirium. We suggest the extensive assessment of the nutritional status, aiming to identify patients at higher risk to develop post-operative delirium and promote its prevention and early treatment.