Objective: To determine the effectiveness of interventions to prevent delirium in hospitalized patients.
Data sources: Two databases, MEDLINE and CINAHL, were searched for relevant articles published from January 1966 to May 1995 and from January 1982 to May 1995 respectively. The bibliographies of identified articles were searched for additional references.
Study selection: Ten articles met the following three inclusion criteria: (a) original research article, (b) published in English or French and (c) controlled trial (nonrandomized or randomized) of an intervention to prevent delirium in hospitalized patients. The validity of the studies was independently assessed according to the criteria for intervention studies proposed by the Evidence-Based medicine Working Group.
Data extraction: Information about study design, patient population, sample size, diagnostic criteria, interventions and results was systematically abstracted from each report. Absolute risk reduction (ARR) for delirium was calculated for each study.
Data synthesis: Eight trials involved surgical patients and two involved elderly medical patients; most of the studies had serious methodological limitations. Among the surgical patients the ARRs ranged from -13% to 81% and were not related to the type or timing of the intervention, or to the personnel involved. Among the elderly medical patients the ARRs ranged from -3% to 3%.
Conclusion: Interventions to prevent delirium among surgical patients may be modestly effective, but further trials are necessary.