Impact of clinical frailty on mortality after elective surgery in patients aged ≥ 90 years admitted to critical care: a binational intensive care registry analysis

Summary Introduction Increasing numbers of patients aged ≥ 90 years require elective surgery. Frailty is increasingly recognised as a key determinant of peri‐operative risk, but high‐quality evidence to understand the impact on outcomes in this age group is limited. Methods We conducted a retrospective cohort study using the Australian and New Zealand Intensive Care Society Adult Patient Database. Patients aged ≥ 90 years admitted to ICU following elective surgery were included, encompassing planned and unplanned ICU admissions. Frailty was assessed at ICU admission using the Clinical Frailty Scale and patients categorised as non‐frail or frail. Propensity score matching was performed to balance age; sex; acute illness severity; and comorbidities. Primary outcome was 1‐year all‐cause mortality. Secondary outcomes included ICU mortality; in‐hospital mortality; return to pre‐admission residence; and ICU and duration of hospital stay. Results The matched cohort comprised 5398 patients (2699 without frailty (Clinical Frailty Scale 1–4) and 2699 living with frailty (Clinical Frailty Scale 5–8)), with good post‐matching covariate balance. Mortality in ICU was low and not significantly different between patients who were frail and non‐frail. Frailty was independently associated with higher in‐hospital mortality (matched hazard ratio (HR) 1.66, 95%CI 1.22–2.27, p = 0.001) and higher 1‐year mortality (matched HR 1.66, 95%CI 1.47–1.87, p < 0.001). Patients without frailty had higher odds of returning to their pre‐admission residence at hospital discharge than patients living with frailty (matched OR 1.45, 95%CI 1.29–1.62, p < 0.001). Patients who were frail experienced longer hospital stays and higher rates of postoperative complications, including delirium and acute renal failure. Discussion Among patients aged ≥ 90 years undergoing elective surgery with postoperative intensive care admission, frailty is strongly associated with prolonged recovery and worse short and long‐term outcomes. Incorporation of frailty assessment into peri‐operative pathways may improve risk stratification, shared decision‐making and personalised care for patients aged ≥ 90 years.