Delirium is significantly associated with hospital frailty risk score derived from administrative data

Delirium is highly prevalent in hospitalised older adults, under-diagnosed and associated with poor outcomes. We aim to determine (i) association of frailty measured using Hospital Frailty Risk Score (HFRS) with delirium, (ii) impact of delirium on mortality, 30-days readmission, extended length of stay (eLOS) and cost (eCOST).

Retrospective cohort study was conducted on 902 older adults ≥75 years discharged from an academic tertiary hospital between March and September 2021. Data was obtained from hospital administrative database.

Delirium was prevalent in 39.1%, 58.1% were female with mean age 85.3 ± 6.2 years. Patients with delirium were significantly older, had higher HFRS, pneumonia, urinary tract infection (UTI), E.coli and Klebsiella infection, constipation, dehydration, stroke and intracranial bleed, with comorbidities including dementia, diabetes, hypertension, hyperlipidaemia and chronic kidney disease. In-hospital mortality, 30-days mortality, 30-days readmission, median LOS and cost was significantly higher. Delirium was significantly associated with at least intermediate frailty (OR = 3.52; CI = 2.48-4.98), dementia (OR = 2.39; CI = 1.61-3.54), UTI (OR = 1.95; CI = 1.29-2.95), constipation (OR = 2.49; CI = 1.43-4.33), Klebsiella infection (OR = 3.06; CI = 1.28-7.30), dehydration (OR = 2.01; CI = 1.40 - 2.88), 30-day mortality (OR = 2.52; CI = 1.42-4.47), 30-day readmission (OR = 2.18; CI = 1.36-3.48), eLOS (OR = 1.80; CI = 1.30-2.49) and eCOST (OR = 1.67; CI = 1.20-2.35).

Delirium was highly prevalent in older inpatients, and associated with dementia, frailty, increased cost, LOS, 30-day readmissions and mortality. Hospital Frailty Risk Score had robust association with delirium and can be auto-populated from electronic medical records. Prospective studies are needed on multicomponent delirium preventive measures in high-risk groups identified by HFRS in acute care settings.