Prevalence of delirium among older nursing home residents: a systematic review and meta-analysis

Delirium is a common geriatric syndrome that presents as an acute change in mental status and is associated with adverse outcomes. The primary aim of this systematic review and meta-analysis was to determine its prevalence in the nursing home population.

MEDLINE, CINAHL, PsycInfo, and Web of Science were searched up to July 11, 2025. Eligible studies reported cross-sectional prevalence data on delirium in the nursing home population, identified using formal diagnostic criteria (DSM-III or ICD-10 onwards) or validated detection tools. Two reviewers independently screened records, extracted data, and assessed quality. A random-effects meta-analysis was conducted to pool the overall prevalence. The reporting adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

A total of nine studies were included, and prevalence data on delirium from eight distinct study populations were analyzed. The prevalence of delirium ranged from 1.0% to 57.9%. The pooled prevalence, encompassing 4291 nursing home residents aged ≥ 65 years, was 18.8% (95% CI: 7.4%-40.2%; I2 = 96.9%; Wald-Chi2-Test = 227.66, p < 0.001). Dementia was present in up to 86.2% of residents. Four studies reported factors associated with the prevalence of delirium, with cognitive impairment most frequently identified as a factor in all four studies.

Delirium was identified as a common health issue in most of the included studies, although prevalence rates were heterogeneous. Future research should prioritize the development of effective detection and prevention strategies, the validation of tools tailored to the nursing home setting, and the conduct of robust, internationally comparable prevalence assessments.