Pre-intensive care unit cognitive status, subsequent disability, and new nursing home admission among critically ill older adults

Rationale: Cognitive impairment is common among older adults, yet little is known about the association of pre-intensive care unit cognitive status with outcomes relevant to older adults maintaining independence after a critical illness. Objectives: To evaluate whether pre-intensive care unit cognitive status is associated with post-intensive care unit disability, new nursing home admission, and mortality after a critical illness among older adults. Methods: In this prospective cohort study, 754 persons aged 70 years or more were monitored from March 1998 to December 2013 with monthly assessments of disability. Cognitive status was assessed every 18 months, using the Mini-Mental State Examination (range, 0-30), with scores classified as 28 or higher (cognitively intact), 24-27 (minimal impairment), and less than 24 (moderate impairment). The primary outcome was disability count (range, 0-13), assessed monthly over 6 months after an intensive care unit stay. The secondary outcomes were incident nursing home admission and time to death after intensive care unit admission. The analytic sample included 391 intensive care unit admissions. Results: The mean age was 83.5 years. The prevalence of moderate impairment, minimal impairment, and intact cognition (the comparison group) was 17.3, 46.2, and 36.5%, respectively. In the multivariable analysis, moderate impairment was associated with nearly a 20% increase in disability over the 6-month follow-up period (adjusted relative risk, 1.19; 95% confidence interval, 1.04-1.36), and minimal impairment was associated with a 16% increase in post-intensive care unit disability (adjusted relative risk, 1.16; 95% confidence interval, 1.02-1.32). Moderate impairment was associated with more than double the likelihood of a new nursing home admission (adjusted odds ratio, 2.37; 95% confidence interval, 1.01-5.55). Survival differed significantly across the three cognitive groups (log-rank P = 0.002), but neither moderate impairment (adjusted hazard ratio, 1.19; 95% confidence interval, 0.65-2.19) nor minimal impairment (adjusted hazard ratio, 1.00; 95% confidence interval, 0.61-1.62) was significantly associated with mortality in the multivariable analysis. Conclusions: Among older adults, any impairment (even minimal) in pre-intensive care unit cognitive status was associated with an increase in post-intensive care unit disability over the 6 months after a critical illness; moderate cognitive impairment doubled the likelihood of a new nursing home admission. Pre-intensive care unit cognitive impairment was not associated with mortality from intensive care unit admission through 6 months of follow-up. Pre-intensive care unit cognitive status may provide prognostic information about the likelihood of older adults maintaining independence after a critical illness.