Adverse outcomes after hospitalization and delirium in persons with Alzheimer disease

Abstract

Background: Hospitalization, frequently complicated by delirium, can be a life-changing event for patients with Alzheimer disease (AD).

Objective: To determine risks for institutionalization, cognitive decline, or death associated with hospitalization and delirium in patients with AD.

Design: Prospective cohort enrolled between 1991 and 2006 into the Massachusetts Alzheimer's Disease Research Center (MADRC) patient registry.

Setting: Community-based.

Participants: 771 persons aged 65 years or older with a clinical diagnosis of AD.

Measurements: Hospitalization, delirium, death, and institutionalization were identified through administrative databases. Cognitive decline was defined as a decrease of 4 or more points on the Blessed Information-Memory-Concentration test score. Multivariate analysis was used to calculate adjusted relative risks (RRs).

Results: Of 771 participants with AD, 367 (48%) were hospitalized and 194 (25%) developed delirium. Hospitalized patients who did not have delirium had an increased risk for death (adjusted RR, 4.7 [95% CI, 1.9 to 11.6]) and institutionalization (adjusted RR, 6.9 [CI, 4.0 to 11.7]). With delirium, risk for death (adjusted RR, 5.4 [CI, 2.3 to 12.5]) and institutionalization (adjusted RR, 9.3 [CI, 5.5 to 15.7]) increased further. With hospitalization and delirium, the adjusted RR for cognitive decline for patients with AD was 1.6 (CI, 1.2 to 2.3). Among hospitalized patients with AD, 21% of the incidences of cognitive decline, 15% of institutionalization, and 6% of deaths were associated with delirium.

Limitations: Cognitive outcome was missing in 291 patients. Sensitivity analysis was performed to test the effect of missing data, and a composite outcome was used to decrease the effect of missing data.

Conclusion: Approximately 1 in 8 hospitalized patients with AD who develop delirium will have at least 1 adverse outcome, including death, institutionalization, or cognitive decline, associated with delirium. Delirium prevention may represent an important strategy for reducing adverse outcomes in this population.

Figure 1. Temporal course of outcomes used in this study

Institutionalization and death are events that happen within 1 y of hospitalization. Median days to event refers to the median length of time from one outcome to the next. MADRC = Massachusetts Alzheimer’s Disease Research Center; NA = not available.

Figure 2. Overlap of outcomes of hospitalization and delirium combined to form the composite outcome

The sizes of the circles and overlaps are proportional to the total number of patients with those outcomes. The dotted diamonds indicate missing data for the outcome of cognitive decline, because classification of these participants inside (or outside) of the cognitive decline circle could not be made. Some cases where the outcome of cognitive decline was not known with certainty included persons who were known to have died (n = 20), who had been institutionalized and then died (n = 24), or who were institutionalized (n = 66). An additional 181 participants were known to be alive, but their outcome of cognitive decline was not known. The total number indicated for each outcome includes those who had missing data.