Association between frailty and short- and long-term outcomes among critically ill patients: a multicentre prospective cohort study

Abstract

Background: Frailty is a multidimensional syndrome characterized by loss of physiologic and cognitive reserves that confers vulnerability to adverse outcomes. We determined the prevalence, correlates and outcomes associated with frailty among adults admitted to intensive care.

Methods: We prospectively enrolled 421 critically ill adults aged 50 or more at 6 hospitals across the province of Alberta. The primary exposure was frailty, defined by a score greater than 4 on the Clinical Frailty Scale. The primary outcome measure was in-hospital mortality. Secondary outcome measures included adverse events, 1-year mortality and quality of life.

Results: The prevalence of frailty was 32.8% (95% confidence interval [CI] 28.3%-37.5%). Frail patients were older, were more likely to be female, and had more comorbidities and greater functional dependence than those who were not frail. In-hospital mortality was higher among frail patients than among non-frail patients (32% v. 16%; adjusted odds ratio [OR] 1.81, 95% CI 1.09-3.01) and remained higher at 1 year (48% v. 25%; adjusted hazard ratio 1.82, 95% CI 1.28-2.60). Major adverse events were more common among frail patients (39% v. 29%; OR 1.54, 95% CI 1.01-2.37). Compared with nonfrail survivors, frail survivors were more likely to become functionally dependent (71% v. 52%; OR 2.25, 95% CI 1.03-4.89), had significantly lower quality of life and were more often readmitted to hospital (56% v. 39%; OR 1.98, 95% CI 1.22-3.23) in the 12 months following enrolment.

Interpretation: Frailty was common among critically ill adults aged 50 and older and identified a population at increased risk of adverse events, morbidity and mortality. Diagnosis of frailty could improve prognostication and identify a vulnerable population that might benefit from follow-up and intervention.

Figure 1:

Selection of critically ill patients for the study cohort.

Figure 2:

Distribution of Clinical Frailty Scale scores and prevalence of frailty (score > 4) among the participants.

Figure 3:

Adjusted hazard ratios for death within 12 months after admission to an intensive care unit, stratified by Clinical Frailty Scale score (score > 4 indicates frailty). Hazard ratios greater than 1.0 indicate an increased risk of death. The models were adjusted as follows: model 1 for age and sex; model 2 for age, sex and Elixhauser score (comorbidity indicator); model 3 for age, sex, Elixhauser score and non–age-specific Acute Physiology and Chronic Health Evaluation (APACHE) II score (illness severity); model 4 for age, sex, Elixhauser score and Sequential Organ Failure Assessment (SOFA) score (presence and severity of organ dysfunction); and model 5 for age, sex, Elixhauser score, non–age-specific APACHE II score and hospital type (tertiary care/academic v. community). CI = confidence interval, ref = reference group.

Figure 4:

Kaplan–Meier survival curves stratified by Clinical Frailty Scale score.