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.

BackgroundFrailty is associated with poor prognosis, but the multitude of definitions and scales of assessment makes the impact on outcomes difficult to assess. The aim of this study was to quantify the effect of frailty on postoperative morbidity and mortality, and long‐term mortality after major abdominal surgery, and to evaluate the performance of different frailty metrics.MethodsAn extended literature search was performed to retrieve all original articles investigating whether frailty could affect outcomes after elective major abdominal surgery in adult populations. All possible definitions of frailty were considered. A random‐effects meta‐analysis was carried out for all outcomes of interest. For postoperative morbidity and mortality, overall effect sizes were estimated as odds ratios (OR), whereas the hazard ratio (HR) was calculated for long‐term mortality. The potential effect of the number of domains of the frailty indices was explored through meta‐regression at moderator analysis.ResultsA total of 35 studies with 1 153 684 patients were analysed. Frailty was associated with a significantly increased risk of postoperative major morbidity (OR 2·56, 95 per cent c.i. 2·08 to 3·16), short‐term mortality (OR 5·77, 4·41 to 7·55) and long‐term mortality (HR 2·71, 1·63 to 4·49). All domains were significantly associated with the occurrence of postoperative major morbidity, with ORs ranging from 1·09 (1·00 to 1·18) for co‐morbidity to 2·52 (1·32 to 4·80) for sarcopenia. No moderator effect was observed according to the number of frailty components.ConclusionRegardless of the definition and combination of domains, frailty was significantly associated with an increased risk of postoperative morbidity and mortality after major abdominal surgery.

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