Frailty is not independently associated with intensive care unit length of stay: An observational study.

Background: Frailty is independently associated with morbidity and mortality in critically ill patients. However, the association between preadmission frailty and the degree of treatment received in the intensive care unit (ICU) remains unclear.

Objective: To describe patient length of stay in an ICU and the treatments provided according to the extent of patient frailty.

Methods: Single-centre retrospective cohort study of adult patients admitted to a tertiary ICU between January 2018 and December 2019. Frailty was assessed using the Clinical Frailty Scale (CFS). The primary outcome was ICU length of stay stratified by CFS score (1-8). Secondary outcomes were the proportion of patients with each CFS score treated with vasoactive agents, invasive ventilation, noninvasive ventilation, renal replacement therapy, and tracheostomy. Poisson regression and competing risks regression was used to analyse associations between ICU length of stay and potential confounders.

Results: The study cohort comprised 2743 patients, with CFS scores known for 2272 (83%). Length of stay in the ICU increased with each increment in the CFS up to a score of 5, beyond which it decreased with higher frailty scores. After adjusting for age, illness severity, admission type, and treatment limitation, CFS scores were not independently associated with length of stay in the ICU (P = 0.31). The proportion of patients receiving specific ICU treatments peaked at different CFS scores, being highest for vasoactive agents at CFS 5 (47%), invasive ventilation CFS 3 (51%), noninvasive ventilation CFS 6 (11%), renal replacement therapy CFS 6 (8.2%), and tracheostomy CFS 5 (2.2%). Increasing frailty was associated with increased mortality and discharge to a destination other than home.

Conclusions: The extent of frailty is not independently associated with length of stay in the ICU. The proportion of patients receiving specific ICU treatments peaked at different CFS scores.