Prevalence, Risk Factors, and Impact of Delirium on Hospitalized Older Adults With Dementia: A Systematic Review and Meta-Analysis

Abstract

Objectives: High prevalence of delirium superimposed on dementia (DSD) was previously reported, with associated negative impact on hospitalized older adults. However, data were conflicting, and no meta-analysis has been conducted. Although dementia is the leading risk factor for delirium, risk factors for DSD have not been adequately studied. This systematic review and meta-analysis aims to elucidate the prevalence, risk factors, and impact of DSD in hospitalized older adults. Comparisons were made between older adults with DSD and persons with dementia alone (PWDs).

Design: Systematic review and meta-analysis.

Setting and participants: Observational studies reporting prevalence, risk factors, or impact of DSD in hospitalized older adults.

Methods: Database search was conducted till December 2020 in PubMed, Embase, CENTRAL, PsycINFO, CINAHL, Scopus, Web of Science, ProQuest, and OpenGrey for relevant primary and secondary studies. A piloted data collection form was used for data extraction, and methodological quality was assessed using Joanna Briggs Institute critical appraisal checklists. Meta-analyses, with risk ratio and mean differences as effect measures, were performed using random effects model with Review Manager software. Cochran's Q and I² statistics were used to assess heterogeneity, which was investigated using subgroup analyses.

Results: A total of 81 studies were eligible. The pooled prevalence of DSD was 48.9%, with the highest prevalence found in the Americas and orthopedic wards. Risk factors, including nonmodifiable hospital-, illness-, and medication-related factors, were found to precipitate DSD. Patients with DSD had longer length of hospitalization, disclosed worse cognitive and functional outcomes, and a higher risk of institutionalization and mortality than patients with dementia.

Conclusions and implications: These findings suggested high prevalence and detrimental impact of DSD in hospitalized older adults, highlighting a need for early identification, prevention, and treatments. Further research on risk factors of DSD should be conducted as data were sparse and conflicting. Future high-quality studies regarding DSD are warranted to improve knowledge of this common but under-recognized phenomenon.

Keywords: Dementia; delirium; delirium superimposed on dementia; meta-analysis; older adults; prevalence; risk factors.