Frailty and Subsequent Disability and Mortality among Patients with Critical Illness

Abstract

Rationale: The prevalence of frailty (diminished physiologic reserve) and its effect on outcomes for those aged 18 years and older with critical illness is unclear.

Objectives: We hypothesized greater frailty would be associated with subsequent mortality, disability, and cognitive impairment, regardless of age.

Methods: At enrollment, we measured frailty using the Clinical Frailty Scale (range, 1 [very fit] to 7 [severely frail]). At 3 and 12 months post-discharge, we assessed vital status, instrumental activities of daily living, basic activities of daily living, and cognition. We used multivariable regression to analyze associations between Clinical Frailty Scale scores and outcomes, adjusting for age, sex, education, comorbidities, baseline disability, baseline cognition, severity of illness, delirium, coma, sepsis, mechanical ventilation, and sedatives/opiates.

Measurements and main results: We enrolled 1,040 patients who were a median (interquartile range) of 62 (53-72) years old and who had a median Clinical Frailty Scale score of 3 (3-5). Half of those with clinical frailty (i.e., Clinical Frailty Scale score ≥5) were younger than 65 years old. Greater Clinical Frailty Scale scores were independently associated with greater mortality (P = 0.01 at 3 mo and P < 0.001 at 12 mo) and with greater odds of disability in instrumental activities of daily living (P = 0.04 at 3 mo and P = 0.002 at 12 mo). Clinical Frailty Scale scores were not associated with disability in basic activities of daily living or with cognition.

Conclusions: Frailty is common in critically ill adults aged 18 years and older and is independently associated with increased mortality and greater disability. Future studies should explore routine screening for clinical frailty in critically ill patients of all ages. Interventions to reduce mortality and disability among patients with heightened vulnerability should be developed and tested. Clinical trial registered with www.clinicaltrials.gov (NCT 00392795 and NCT 00400062).

Trial registration: ClinicalTrials.gov NCT00392795 NCT00400062.

Keywords: activities of daily living; critical illness; frailty; survivors.

Figure 1.

Distribution of Clinical Frailty Scale (CFS) scores according to age. Box plots represent the median (horizontal line) and interquartile range (top and bottom of box represent the 75th percentile and 25th percentile, respectively) of CFS scores for each age group. Scatter plots represent the CFS score for individual patients.

Figure 2.

Kaplan-Meier survival curves indicate an incremental worsening of survival with increasing Clinical Frailty Scale (CFS) scores. Numbers to the right of each curve indicate CFS score.

Figure 3.

These panels display Clinical Frailty Scale scores on the x-axis versus the adjusted probability of a higher Functional Activities Questionnaire score on the y-axis. Point estimates are indicated with blue dots, with 95% confidence intervals indicated by blue bars. The rug plot (just below the x-axis) shows the distribution of Clinical Frailty Scale scores. Overall, higher baseline Clinical Frailty Scale scores were independently associated with greater probability of higher Functional Activities Questionnaire scores at 12-month follow-up (P = 0.002), indicating new or worsened disability in instrumental activities of daily living. This association was modified by the duration of delirium (P = 0.14). Therefore, we present the association between Clinical Frailty Scale score and Functional Activities Questionnaire score for patients who had 0 days of delirium (A), 2 days of delirium (the 50th percentile of delirium duration, B), and those with 5 days of delirium (the 75th percentile of delirium duration, C). FAQ = Functional Activities Questionnaire.