RESUMO
BACKGROUND: Delirium increases mortality and length of stay among hospital inpatients. Little is known about the incidence of delirium among inpatients receiving care in internal medicine nursing units in Spain. OBJECTIVES: The aim of this study was to estimate frequency of delirium onset among internal medicine inpatients and identify factors associated with delirium onset using nursing records and administrative databases. METHODS: Retrospective cohort study of 744 patients hospitalized in an internal medicine department in October 2010 and January, May, and October 2011. Data concerning occurrence of delirium, age, gender, living in a nursing residence, Barthel Index of activities of daily living, Norton scale for pressure ulcer risk, intravenous fluid therapy, urinary catheterization, presence of pressure ulcers, major diagnostic category at discharge, length of stay, and mean weight in the diagnosis-related group were gathered for each patient. Backward stepwise logistic regression was used to identify factors associated with onset of delirium. RESULTS: Ninety-seven (13%) patients experienced delirium. Factors associated with delirium were age (OR = 1.03, 95% CI [1.01, 1.06]), Barthel Index (OR = 0.99. 95% CI [0.98, 0.99]), and urinary catheterization (OR = 2.00, 95% CI [1.19, 3.68]). CONCLUSION: Increased age and presence of a urinary catheter were associated with increased onset of delirium, whereas higher levels of independence in activities of daily living were protective.