Frailty and Delirium in Older Adults: A Systematic Review and Meta-Analysis of the Literature

OBJECTIVES: To evaluate the relationship between frailty and delirium. DESIGN: Systematic review and meta-analysis. SETTING: MEDLINE, EMBASE, PubMed, Scopus, Web of Science, and Google Scholar databases were searched for articles on frailty and delirium published on or before October 31, 2017. PARTICIPANTS: Individuals aged 65 and older. MEASUREMENTS: Two authors independently reviewed all English-language citations, extracted relevant data, and assessed studies for potential bias. Articles involving pediatric or neurosurgical populations, alcohol or substance abuse, psychiatric illness, head trauma, or stroke, as well as review articles, letters, and case reports were excluded. Studies underwent qualitative or quantitative analysis according to specified criteria. Using a random-effects or fixed-effects model, relative risk (RR) was calculated for the effect of frailty as a predictor of subsequent delirium. Heterogeneity was tested using Q and I2 statistics. RESULTS: We identified 1,626 articles from our initial search, of which 20 fulfilled the selection criteria (N=5,541 participants, mean age 77.8). Eight studies were eligible for meta-analysis, showing a significant association between Q2 frailty and subsequent delirium (RR = 2.19, 95% confidence interval = 1.65–2.91). There was low variability among studies in the measures of association between frailty and delirium (I2 2.24, p-value Q-statistic =.41) but high heterogeneity in the methods used to assess the two conditions. CONCLUSION: This systematic review and meta-analysis supports the existence of an independent relationship between frailty and delirium, although there is notable methodological heterogeneity between the methods used to assess the 2 conditions. Future studies are needed to better delineate the dynamics between these syndromes.