A Cochrane review 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.
In another trial of low dose haloperidol prophylaxis, there was no difference in delirium incidence but the severity and duration of a delirium episode, and length of hospital stay were all reduced. No completed studies were identified in hospitalised medical care of the elderly, general surgery, cancer or intensive care patients. In outcomes, no studies examined for death, use of psychotropic medication, activities of daily living, psychological morbidity, quality of life, carers or staff psychological morbidity, cost of intervention and cost to health care services. Outcomes were only reported up to discharge, with no studies reporting medium or longer-term effects.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.