The FRAIL-FIT 30 Study - Factors influencing 30-day mortality in frail patients admitted to ICU: A retrospective observational cohort study

Abstract

Background: Frailty is a multi-dimensional syndrome of reduced reserve, resulting from overlapping physiological decrements across multiple systems. The contributing factors, temporality and magnitude of frailty's effect on mortality after ICU admission are unclear. This study assessed frailty's impact on mortality and life sustaining therapy (LST) use, following ICU admission.

Methods: This single-centre retrospective observational cohort study analysed data collected prospectively in Glasgow Royal Infirmary ICU. Of 684 eligible patients, 171 were frail and 513 were non-frail. Frailty was quantified using the Rockwood Clinical Frailty Scale (CFS). All patients were followed up 1-year after ICU admission. The primary outcome was all-cause mortality at 30-days post-ICU admission. Key secondary outcomes included mortality at 1-year and LST use.

Results: Frail patients were significantly less likely to survive 30-days post-ICU admission (61.4% vs 81.1%, p < 0.001). This continued to 1-year (48.5% vs 68.2%, p < 0.001). Frailty significantly increased mortality hazards in covariate-adjusted analyses at 30-days (HR 1.56; 95%CI 1.14-2.15; p = 0.006), and 1-year (HR 1.35; 95%CI 1.03-1.76; p = 0.028). Single-point CFS increases were associated with a 30-day mortality hazard of 1.23 (95%CI 1.13-1.34; p < 0.001) in unadjusted analyses, and 1.11 (95%CI 1.01-1.22; p = 0.026) after covariate adjustment. Frail patients received significantly more days of LST (median[IQR]: 5[3,11] vs 4[2,9], p = 0.008).

Conclusion: Frailty was significantly associated with greater mortality at all time points studied, but most notably in the first 30-days post-ICU admission. This was despite greater LST use. The accrual effect of frailty increased adverse outcomes. Point-by-point use of frailty scoring could allow for more informed decision making in ICU.

Keywords: Clinical Frailty Scale; Frailty; intensive care; 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.

Clinical Frailty Scale score distributions. Bar graph of the percentage distributions of each clinical frailty score (CFS).

Figure 3.

Unadjusted survival curves to 1-year, 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 4.

Unadjusted survival curves to 1-year, Stratified by frailty subgroups. Kaplan Meier survival curves representing survival to 365 days, grouped by frailty subgroups. Fit patients had clinical frailty scale (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.