title: [Delirium in stroke patients : Critical analysis of statistical procedures for the identification of risk factors].
abstract: BACKGROUND
  Delirium is a relevant complication following an acute stroke. It is a multifactor occurrence with numerous interacting risk factors that alternately influence each other.
  
  
  OBJECTIVE
  The risk factors of delirium in stroke patients are often based on limited clinical studies. The statistical procedures and clinical relevance of delirium related risk factors in adult stroke patients should therefore be questioned.
  
  
  METHODS
  This secondary analysis includes clinically relevant studies that give evidence for the clinical relevance and statistical significance of delirium-associated risk factors in stroke patients. The quality of the reporting of regression analyses was assessed using Ottenbacher's quality criteria. The delirium-associated risk factors identified were examined with regard to statistical significance using the Bonferroni method of multiple testing for forming incorrect positive hypotheses. This was followed by a literature-based discussion on clinical relevance.
  
  
  RESULTS
  Nine clinical studies were included. None of the studies fulfilled all the prerequisites and assumptions given for the reporting of regression analyses according to Ottenbacher. Of the 108 delirium-associated risk factors, a total of 48 (44.4%) were significant, whereby a total of 28 (58.3%) were false positive after Bonferroni correction. Following a literature-based discussion on clinical relevance, the assumption of statistical significance and clinical relevance could be found for only four risk factors (dementia or cognitive impairment, total anterior infarct, severe infarct and infections).
  
  
  CONCLUSIONS
  The statistical procedures used in the existing literature are questionable, as are their results. A post-hoc analysis and critical appraisal reduced the number of possible delirium-associated risk factors to just a few clinically relevant factors.
authors.affiliation: Pflegeforschung, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Brunswiker Str. 10, 24105, Kiel, Deutschland. Peter.Nydahl@uksh.de.
authors.forename: P
authors.initials: P
authors.lastname: Nydahl
authors.affiliation: Klinik für Neurologie, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Deutschland.
authors.forename: N G
authors.initials: NG
authors.lastname: Margraf
authors.affiliation: Institut für Pflegewissenschaft und -praxis, Paracelsus Medizinische Privatuniversität Salzburg, Salzburg, Österreich.
authors.forename: A
authors.initials: A
authors.lastname: Ewers
mesh_terms: D015897:Comorbidity; D003693:Delirium / Q000209:etiology*; D006801:Humans; D012044:Regression Analysis; D012307:Risk Factors; D020521:Stroke / Q000150:complications*
keywords: Cognitive dysfunction; Delirium; Regression analysis; Risk factors; Stroke