Publications

BACKGROUND

Delirium is common in hospitalised older adults and is associated with mortality. Whether this prognostic association varies by baseline cognition is uncertain. We evaluated the association between delirium and 90-day mortality and whether baseline cognitive status modified this relationship.

METHODS

We conducted a prospective, multicentre cohort study of adults aged ≥65 years admitted to 43 hospitals in five countries (Brazil, Angola, Chile, Colombia and Portugal; June 2022-December 2023). Delirium was assessed using the Confusion Assessment Method; cognitive status was measured using an informant-based Clinical Dementia Rating (CDR). Mortality within 90 days of admission was ascertained from hospital records, structured telephone follow-up by blinded assessors and registry linkage. We used mixed-effects survival models with random intercepts (state/province and study centre) and sequential adjustment for sociodemographic, clinical and hospital-related factors. Effect modification by CDR was examined with stratified analyses.

RESULTS

Among 2556 patients (mean age 79 ± 9 years; 56% women), delirium occurred in 957 (37%). Delirium frequency rose with worsening cognition (CDR 0: 16%; CDR 0.5: 27%; CDR 1: 59%; CDR 2-3: 77%; P < .001). Delirium was associated with higher 90-day mortality (adjusted HR = 3.45; 95% CI = 2.83-4.20). The relative association with mortality was greatest in no dementia and attenuated in moderate-severe dementia. At 90 days, cumulative mortality was 54% with delirium vs. 15% without in CDR 0 (HR = 4.40; 95% CI = 3.15-6.16) and 36% vs. 17% in CDR 2-3 (HR = 2.22; 95% CI = 1.34-3.66). Patients with delirium also experienced more in-hospital complications (nosocomial infection, functional decline and prolonged stay).

CONCLUSIONS

Although delirium was more frequent among patients with dementia, its relative association with 90-day mortality was strongest in those with no baseline dementia. The results provide a strong rationale for intervention trials to determine whether delirium prevention and management strategies can reduce mortality, particularly among patients without known dementia.