Cognitive aging and rate of hospitalization in an urban population of older people.

Background: The association of age-related cognitive change with hospitalization is not well understood.

Methods: At 3-year intervals for a mean of 8.7 years, 2,273 older residents of a geographically defined urban community underwent cognitive testing from which a global measure was derived. Hospitalization data were obtained from Part A Medicare beneficiary records. The association of level of cognitive function and rate of cognitive decline in each 3-year interval with subsequent rate of hospitalization was assessed using mixed-effects count regression models.

Results: There were 9,091 hospitalizations involving 1,810 of the 2,273 individuals in the cohort (79.6%). Rate of hospitalization increased by 9.7% (95% confidence interval [CI]: 7.2, 12.3) with each additional study year; by 32.7% (95% CI: 26.8, 38.0) for each 1 point lower on the global cognitive measure at the beginning of an observation interval; and by 24.3% (95% CI: 16.6, 32.6) for each 1-point decrease in the global cognitive measure during the previous observation period. These associations persisted after adjustment for comorbidities and exclusion of those with a Mini-Mental State Examination score less than 26.

Conclusion: Individual differences in trajectories of cognitive aging are associated with subsequent risk of hospitalization.