Delirium may be associated with adverse outcomes in hospitalized patients with Alzheimer's disease

Patients with Alzheimer's disease who develop delirium during hospitalization are more likely to have adverse outcomes, according to a new study.

Researchers performed a prospective cohort study of patients with Alzheimer's disease who were enrolled in the Massachusetts Alzheimer's Disease Research Center patient registry from 1991 to 2006. The goal of the study was to determine the association between hospitalization and delirium and risks for institutionalization, cognitive decline and death. The authors defined cognitive decline as a decrease of at least four points on the Blessed Information-Memory-Concentration test score. Adjusted relative risks (RRs) were calculated by using multivariate analysis. The study results appear in the June 19 Annals of Internal Medicine.

A total of 771 patients at least 65 years of age (mean age, 77.2 years) with a diagnosis of Alzheimer's disease were included in the study. Fifty-seven percent were women, and 95% were white. Over the study period, 367 patients (48%) were hospitalized and 194 (25%) developed delirium. Risks for death and institutionalization were higher in hospitalized patients than in nonhospitalized patients (adjusted RRs, 4.7 and 6.9, respectively) and were increased further in hospitalized patients who developed delirium (adjusted RRs, 5.4 and 9.3, respectively). Hospitalized patients who developed delirium also had an adjusted RR of 1.6 for cognitive decline. Overall, 21% of cognitive decline, 15% of institutionalizations, and 6% of deaths in hospitalized patients were determined to be associated with delirium.

The authors acknowledged that their study was nonrandomized, that some data were missing, and that ethnic minorities were not well represented, among other limitations. However, they concluded that delirium during hospitalization will lead to at least one adverse outcome in approximately one in eight patients with Alzheimer's disease. “Further investigation is greatly needed to determine whether prevention of hospitalization and delirium can decrease the attributable risk for death, institutionalization, and cognitive impairment in the vulnerable and increasing population of persons with [Alzheimer's disease],” the authors wrote.