The Association of Frailty With Post-ICU Disability, Nursing Home Admission, and Mortality: A Longitudinal Study

Abstract

Background: Frailty is a strong indicator of vulnerability among older persons, but its association with ICU outcomes has not been evaluated prospectively (ie, with objective measurements obtained prior to ICU admission). Our objective was to prospectively evaluate the relationship between frailty and post-ICU disability, incident nursing home admission, and death.

Methods: The parent cohort included 754 adults aged ≥ 70 years, who were evaluated monthly for disability in 13 functional activities and every 18 months for frailty (1998-2014). Frailty was assessed using the Fried index, where frailty, prefrailty, and nonfrailty were defined, respectively, as at least three, one or two, and zero criteria (of five). The analytic sample included 391 ICU admissions.

Results: The mean age was 84.0 years. Frailty and prefrailty were present prior to 213 (54.5%) and 140 (35.8%) of the 391 admissions, respectively. Relative to nonfrailty, frailty was associated with 41% greater disability over the 6 months following a critical illness (adjusted risk ratio, 1.41; 95% CI, 1.12-1.78); prefrailty conferred 28% greater disability (adjusted risk ratio, 1.28; 95% CI, 1.01-1.63). Frailty (odds ratio, 3.52; 95% CI, 1.23-10.08), but not prefrailty (odds ratio, 2.01; 95% CI, 0.77-5.24), was associated with increased nursing home admission. Each one-point increase in frailty count (range, 0-5) was associated with double the likelihood of death (hazard ratio, 2.00; 95% CI, 1.33-3.00) through 6 months of follow-up.

Conclusions: Pre-ICU frailty status was associated with increased post-ICU disability and new nursing home admission among ICU survivors, and death among all admissions. Pre-ICU frailty status may provide prognostic information about outcomes after a critical illness.

Keywords: aging; critical care; disability; epidemiology.

Figure 1

Assembly of analytic samples from the parent cohort. All ICU admissions from study enrollment through December 2013 were identified. Because frailty was updated during the comprehensive assessments, only the first ICU admission per 18-month interval was included, yielding 391 eligible ICU admissions. For the primary outcome of post-ICU disability count, the analytic sample included 266 ICU admissions contributed by participants who survived to the first post-ICU monthly interview. For the secondary outcome of incident nursing home admission, the analytic sample included 267 ICU admissions contributed by participants who were community-living prior to ICU admission. For the mortality outcome, the analytic sample included all 391 ICU admissions. NH = nursing home. Reprinted with permission of the American Thoracic Society. Copyright 2018 American Thoracic Society. Ferrante LE, Murphy TE, Gahbauer EA, Leo-Summers LS, Pisani MA, Gill TM. Pre-Intensive care unit cognitive status, subsequent disability, and new nursing home admission among critically ill older adults. Ann Am Thor Soc. 2018; 15:622-629. Annals of the American Thoracic Society is an official journal of the American Thoracic Society.

Figure 2

Pre- and post-ICU disability count by frailty status (N = 266) over 6 months of post-ICU follow-up. Values (ranging from 0 to 13) are unadjusted and error bars represent standard deviations. As a reference point, the pre-ICU disability counts (from the month prior to ICU admission) are included at month 0. The 266 ICU admissions were contributed by 215 participants who survived to their first post-ICU monthly interview. The number of survivors alive at each month of follow-up by frailty status is presented below the figure. There was no attrition for reasons other than death.

Figure 3

Kaplan-Meier graph demonstrating survival by frailty group from admission through 6 months of posthospital follow-up (N = 391). Group sizes were: not frail, n = 38 (9.7%); prefrail, n = 140 (35.8%); and frail, n = 213 (54.5%). Because the ICU admission date was not available in Medicare claims, the hospital admission date was used as a proxy. Follow-up extended to 210 days because each ICU admission was nested within a hospitalization, which sometimes extended beyond 30 days. The vertical tick marks represent censored observations.