Delirium in older adults is associated with development of new dementia: a systematic review and meta‐analysis

Abstract

Objectives Observational studies have examined the association between delirium and development of new dementia. However, no recent review has collectively assessed the available evidence quantitatively and qualitatively. We systematically reviewed and critically evaluated the literature regarding the association between delirium and dementia, and calculated the odds of developing new dementia after having delirium. Methods This systematic review and meta‐analysis was conducted according to Preferred reporting items for systematic reviews and meta‐analyses guidelines. MEDLINE, EMBASE and PsycINFO, were searched for English‐language articles that compared the incidence of new dementia in older adult (≥65) inpatients with delirium, to inpatients without delirium. A random effects model was used for meta‐analysis, and overall effect size was calculated using reported raw data of event counts. The Newcastle‐Ottawa Quality Assessment scale assessed risk of bias. Results Six observational studies met eligibility criteria, with follow‐up times ranging from six months to five years. Four looked at hip fracture surgical patients; one was on cardiac surgery patients and one examined geriatric medical patients. All studies excluded patients with pre‐existing dementia. Pooled meta‐analysis revealed that older adult inpatients who developed delirium had almost twelve times the odds of subsequently developing new dementia compared to non‐delirious patients (OR = 11.9 [95% CI: 7.29–19.6]; p < 0.001). Conclusions Older adult inpatients who develop delirium are at significant risk of subsequently developing dementia. This emphasises the importance of delirium prevention and cognitive monitoring post‐delirium. The included studies mainly examined post‐surgical patients—further research on medical and intensive care unit cohorts is warranted. Future studies should assess whether delirium duration, severity and subtype influence the risk of developing dementia.

In-Hospital Delirium as a Prognostic Factor for New Cognitive Disorder in a 1-Year Post-Hip Fracture Follow-Up

“…Likewise, our results firmly support the hypothesis that delirium increases the risk of developing dementia. However, inconsistencies in the definitions of delirium and small sample sizes complicate the evaluation of the process from delirium to dementia as well as the comparison between studies [20]. In our data, the incidence of delirium in patients with no pre-existing cognitive disorder was 18%, which concurs with the existing literature but is lower than in some other studies [4,28].…”

“…Also, the rigorous pathway to diagnose cognitive disorders post-hip fracture is commendable. Only few studies have been conducted to specifically investigate the link between delirium and development of reliably diagnosed dementia [20]. The CAM test has been considered the gold standard in detecting delirium although it is not the most accurate means of detecting hypoactive subtypes [39].…”

“…A review by Goldberg and colleagues [19] reported that hospitalized patients with delirium had 2.30 times the odds of cognitive decline compared to patients without delirium. A recent systematic review and meta-analysis by Pereira and co-workers [20] found 6 studies focusing on the association of delirium and new dementia in older hospitalized patients. Patients with pre-existing dementia were excluded.…”

“…Patients with pre-existing dementia were excluded. The article reported a 12-fold increase in the odds of developing dementia after in-hospital delirium [20]. In this study, we investigate the association between in-hospital delirium, as measured by the Confusion Assessment Method (CAM), and new cognitive disorder in a 1-year follow-up in older hip fracture patients with no known diagnosis of cognitive disorder preoperatively.…”

Profiling Delirium Progression in Elderly Patients via Continuous-Time Markov Multi-State Transition Models

“…Delirium is also considered as a risk factor for clinical outcomes such as mortality in several categories of subjects; for example, COVID-19 patients [19], vascular surgery patients [20], oncological [21], and critically ill adults [22]. Delirium has also been considered a factor influencing the risk of developing other new forms of dementia [23] and as a possible issue affecting the quality of life [24]. In these research studies, the statistical methods mostly used are linear regression [16] or Cox proportional hazard model (shortly Cox model) [16,21,22].…”