title: Risk factors for incident delirium among older people in acute hospital medical units: a systematic review and meta-analysis.
abstract: BACKGROUND
  delirium affects up to 40% of older hospitalised patients, but there has been no systematic review focussing on risk factors for incident delirium in older medical inpatients. We aimed to synthesise data on risk factors for incident delirium and where possible conduct meta-analysis of these.
  
  
  METHODS
  PubMed and Web of Science databases were searched (January 1987-August 2013). Studies were quality rated using the Newcastle-Ottawa Scale. We used the Mantel-Haenszel and inverse variance method to estimate the pooled odds ratio (OR) or mean difference for individual risk factors.
  
  
  RESULTS
  eleven articles met inclusion criteria and were included for review. Total study population 2338 (411 patients with delirium/1927 controls). The commonest factors significantly associated with delirium were dementia, older age, co-morbid illness, severity of medical illness, infection, 'high-risk' medication use, diminished activities of daily living, immobility, sensory impairment, urinary catheterisation, urea and electrolyte imbalance and malnutrition. In pooled analyses, dementia (OR 6.62; 95% CI (confidence interval) 4.30, 10.19), illness severity (APACHE II) (MD (mean difference) 3.91; 95% CI 2.22, 5.59), visual impairment (OR 1.89; 95% CI 1.03, 3.47), urinary catheterisation (OR 3.16; 95% CI 1.26, 7.92), low albumin level (MD -3.14; 95% CI -5.99, -0.29) and length of hospital stay (OR 4.85; 95% CI 2.20, 7.50) were statistically significantly associated with delirium.
  
  
  CONCLUSIONS
  we identified risk factors consistently associated with incident delirium following admission. These factors help to highlight older acute medical inpatients at risk of developing delirium during their hospital stay.
authors.affiliation: Tees, Esk and Wear Valleys NHS Foundation Trust, Durham DL2 2TS, UK.
authors.forename: Suman
authors.initials: S
authors.lastname: Ahmed
authors.forename: Baptiste
authors.initials: B
authors.lastname: Leurent
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Sampson
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D015897:Comorbidity; D016001:Confidence Intervals; D003693:Delirium / Q000453:epidemiology / Q000209:etiology; D003704:Dementia / Q000150:complications*; D064420:Drug-Related Side Effects and Adverse Reactions / Q000150:complications*; D005260:Female; D015577:Geriatric Assessment; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007239:Infections / Q000150:complications*; D008297:Male; D044342:Malnutrition / Q000150:complications*; D016017:Odds Ratio; D012307:Risk Factors; D012678:Sensation Disorders / Q000150:complications*; D012720:Severity of Illness Index; D014883:Water-Electrolyte Imbalance / Q000150:complications*
keywords: delirium; hospitalised; medical unit; older people; risk factors