A Cochrane review [Abstract] 1 included 39 studies with a total of 16 082 subjects, assessing 22 different interventions. 32 studies were conducted in patients undergoing surgery, the majority in orthopaedic settings. Multi-component interventions (individualised care, checklists, education/training, attention to sensory deprivation, nutrition, mobilisation etc.) reduced the incidence of delirium compared to usual care (RR 0.69, 95% CI 0.59 to 0.81; 7 studies; n=1950; moderate-quality evidence). Effect sizes were similar in medical and surgical settings. In the subgroup of patients with pre-existing dementia, the effect of multi-component interventions remains uncertain.
Bispectral Index (BIS)-guided anaesthesia reduced the incidence of delirium compared to BIS-blinded anaesthesia or clinical judgement (RR 0.71, 95% CI 0.60 to 0.85; 2 studies; n=2057; moderate quality evidence).
There is no clear evidence that cholinesterase inhibitors, melatonin, or melatonin agonists are effective in preventing delirium compared to placebo (RR 0.68, 95% CI, 0.17 to 2.62; two studies, 113 participants; very low-quality evidence).Three trials provide no clear evidence of an effect of antipsychotic medications as a group on the incidence of delirium. There was no evidence for effectiveness of a typical antipsychotic (haloperidol), however, delirium incidence was lower for patients treated with an atypical antipsychotic (olanzapine) compared to placebo.
Comment: The quality of evidence is downgraded by study quality (lack of blinding of participants and personal in all studies and lack of blinding of outcome assessors in 2 studies) and by heterogeneity in interventions.
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