The FRAIL-FIT study: Frailty's relationship with adverse-event incidence in the longer term, at one year following intensive care unit treatment - A retrospective observational cohort study

Abstract

Introduction: Frailty is a syndrome of decreased reserve and heightened vulnerability. Frailty scoring has potential to facilitate more informed decisions in the intensive care unit. To validate this, its relationship with outcomes must be tested extensively. This study aimed to investigate frailty's impact on adverse outcomes after intensive care unit admission, primarily one-year mortality.

Methods: This single-centre retrospective observational cohort study examined prospectively collected data from 400 intensive care unit patients. Frailty was assessed using the Clinical Frailty Scale and defined as Clinical Frailty Scale ≥ 5. Unadjusted and adjusted analyses tested the relationships of frailty, covariates and outcomes.

Results: Of 400 eligible patients, 111 (27.8%) were frail and 289 (72.3%) were non-frail. Compared to non-frail patients, frail patients were older (62 vs. 56, p < 0.001) and had higher Acute Physiology and Chronic Health Evaluation II scores (22 vs. 19, p < 0.001). Females were more likely to be frail than males (34.1% vs. 22.9% frail, p = 0.018). Frail patients were less likely to survive the intensive care unit (p = 0.03), hospital (p = 0.003) or to one year (p < 0.001). Frailty significantly increased one-year mortality hazards in unadjusted analyses (hazard ratio 1.96; 95% confidence interval 1.41-2.72; p < 0.001) and covariate adjusted analyses (hazard ratio 1.41; 95% confidence interval 1.00-1.98; p = 0.0497). Frail patients had more hospital admissions (p = 0.014) and longer hospital stays within both one year before (p = 0.002) and one year after intensive care unit admission (p = 0.012).

Conclusions: Frailty was common and associated with greater age, female gender, higher sickness severity and more healthcare use. Frailty was significantly associated with greater risks of mortality in both unadjusted and adjusted analyses. Frailty scoring is a promising tool which could improve decision making in intensive care.

Keywords: Clinical Frailty Scale; frail; intensive care unit; mortality.

Figure 1.

Study consort diagram. Flow diagram from screening to analysis, showing reasons for exclusion, with numbers and percentages of patients in each group.

Figure 2.

Unadjusted survival curves stratified by frailty status. Kaplan–Meier survival curves representing survival to 365 days, grouped by frailty status. The number and percentage of patients alive, and still at risk of death at each 30-day time point in each group are displayed in the table below the graph.

Figure 3.

Unadjusted survival curves stratified by frailty subgroups. Kaplan–Meier survival curves representing survival to 365 days, grouped by frailty subgroups. Fit patients had CFS scores of 1 and 2, vulnerable patients were characterised by CFS 3 and 4, and frail patients were defined as CFS 5 and above. The number and percentage of patients alive, and still at risk of death at each 30-day time point in each group are displayed in the table below the graph.