Association Between Critical Care Admissions and Cognitive Trajectories in Older Adults∗

Objectives: Patients requiring admission to an ICU may subsequently experience cognitive decline. Our objective was to investigate longitudinal cognitive trajectories in older adults hospitalized in ICUs. We hypothesized that individuals hospitalized for critical illness develop greater cognitive decline compared with those who do not require ICU admission. Design: A retrospective cohort study using prospectively collected cognitive scores of participants enrolled in the Mayo Clinic Study of Aging and ICU admissions retrospectively ascertained from electronic medical records. A covariate-adjusted linear mixed effects model with random intercepts and slopes assessed the relationship between ICU admissions and the slope of global cognitive z scores and domains scores (memory, attention/executive, visuospatial, and language). Setting: ICU admissions and cognitive scores in the Mayo Clinic Study of Aging from October 1, 2004, to September 11, 2017. Patients: Nondemented participants age 50 through 91 at enrollment in the Mayo Clinic Study of Aging with an initial cognitive assessment and at least one follow-up visit. Interventions: None. Measurements and Main Results: Of 3,673 participants, 372 had at least one ICU admission with median (25-75th percentile) follow-up after first ICU admission of 2.5 years (1.2-4.4 yr). For global cognitive z score, admission to an ICU was associated with greater decline in scores over time compared with participants not requiring ICU admission (difference in annual slope = -0.028; 95% CI, -0.044 to -0.012; p < 0.001). ICU admission was associated with greater declines in memory (-0.029; 95% CI, -0.047 to -0.011; p = 0.002), attention/executive (-0.020; 95% CI, -0.037 to -0.004; p = 0.016), and visuospatial (-0.013; 95% CI, -0.026 to -0.001; p = 0.041) domains. ICU admissions with delirium were associated with greater declines in memory (interaction p = 0.006) and language (interaction p = 0.002) domains than ICU admissions without delirium. Conclusions: In older adults, ICU admission was associated with greater long-term cognitive decline compared with patients without ICU admission. These findings were more pronounced in those who develop delirium while in the ICU.