Association of Hospitalization with Long-Term Cognitive Trajectories in Older Adults

Abstract

Importance: Hospitalizations are associated with cognitive decline in older adults.

Objective: To determine the association between hospitalization characteristics and the trajectory of cognitive function in older adults.

Design: Population-based longitudinal study of cognitive aging.

Setting: Olmsted Medical Center and Mayo Clinic, the only centers in Olmsted County, Minnesota, with hospitalization capacity.

Participants: Individuals without dementia at baseline, with consecutive cognitive assessments from 2004 through 2017, and at least one visit after the age of 60.

Measurements: The primary outcome was longitudinal changes in global cognitive z-score. Secondary outcomes were changes in four cognitive domains: memory, attention/executive function, language, and visuospatial skills. Hospitalization characteristics analyzed included elective versus nonelective, medical versus surgical, critical care versus no critical care admission, and long versus short duration admissions.

Results: Of 4,587 participants, 1,622 had 1 and more hospital admission. Before hospitalization, the average slope of the global z-score was -0.031 units/year. After hospitalization, the rate of annual global z-score accelerated by -0.051 (95% CI = -0.057, -0.045) units, P < .001, resulting in an estimated annual slope after the first hospitalization of -0.082. The accelerated decline was found in all four cognitive domains (memory, visuospatial, language, and executive, all P < .001). The acceleration of the decline in global z-score following hospitalization was greater for medical compared to surgical hospitalizations (slope change following hospitalization = -0.064 vs -0.034 for medical vs surgical, P < .001), and nonelective compared to elective admissions (slope change following hospitalization = -0.075 vs -0.037 for nonelective vs elective, P < .001). The acceleration of cognitive decline was not different for hospitalization with intensive care unit admission versus not.

Conclusions: Hospitalization of older adults is associated with accelerated decline of global and domain-specific cognitive domains, with the rate of decline dependent upon type of admission. The clinical impact of this accelerated decline will depend on the individual's baseline cognitive reserve and expected longevity.

Keywords: Mayo Clinic Study of Aging; cognitive domain; critical care admission; global cognitive z-scores; hospitalization admission.

Figure 1

A and B simulate cognitive trajectories for 2 hypothetical participants (Pt), each with and without hospitalizations during follow-up. Pt 1 is a highly functional 75-year-old college-educated female, married, with no other comorbidities. Pt 2 is a 75-year-old male with high-school diploma, former smoker, moderate comorbidity burden (cardiometabolic conditions = 3), never married, and APOE-ε4 positive. Figure 1 A shows simulated paths of 3 possible hospitalization scenarios (no hospitalization, single hospitalization at 2 years, hospitalization at 2 and 4 years). In each case, the slope of cognitive decline is accelerated following the first hospitalization with an additional, albeit attenuated, decline following the second hospitalization. It is notable that in Participant #1 (Pt 1) who has above average cognitive function at baseline if hospitalizations occurred at 2 and 4 years, the trajectory of cognitive decline remained well above the threshold for cognitive impairment at the end of 8 years of follow-up. However, for Pt 2 who had below average cognitive function at baseline (indicating less cognitive reserve), a single hospitalization at 2 years was associated with an accelerated decline in cognitive function resulting in them reaching the threshold for impairment at approximately 5 years which is 3 years earlier than would have been expected had they not required hospitalization. Similarly, Figure 1 B. shows simulated paths for global cognitive trajectories of the same two hypothetical individuals under scenarios of no hospitalization, a single medical hospitalization at 2 years, and a single surgical hospitalization at 2 years. The interpretation of the clinical implications of hospitalization for these patients is similar to that described in Figure 1 A, although for Pt 2, the time at which they reach the threshold for impairment is more accelerated if they required medical vs. surgical hospitalization.