Delirium is a prevalent syndrome in the hospital setting and the elderly are the most affected. The objective was to assess the safety, clinical effectiveness, and cost effectiveness of interventions for preventing delirium among people aged 65 years or older at hospital admission.

A systematic review of available scientific literature (randomized controlled trials) on the safety, effectiveness, and cost effectiveness of the interventions was conducted. The overall effect size for each type of intervention was estimated through a meta-analysis. A cost-effectiveness study in the context of the Spanish National Healthcare System was performed.

Forty-nine studies were included for the effectiveness and safety assessment (25 on pharmacological interventions, 12 on perioperative interventions, 2 on non-pharmacological interventions, and 10 on multicomponent interventions). The following interventions reduced delirium incidence relative to usual care or placebo: hypnotics and sedatives (13 studies; risk ratio [RR] 0.54: 95% confidence interval [CI] 0.36–0.80); perioperative interventions aimed at limiting opioid use (two studies; RR 0.50, 95% CI: 0.29–0.86); controlling the intensity of general anesthesia (three studies; RR 0.77, 95% CI: 0.59–0.99); and multicomponent interventions (10 studies; RR 0.62, 95% CI: 0.54–0.72). In addition, multicomponent interventions reduced the duration (mean difference −1.18, 95% CI: −1.95 - −0.40) and severity of delirium (standardized mean difference −0.98, 95% CI: −1.46 - −0.49), while dexmedetomidine reduced the duration of delirium (mean difference −0.70, 95% CI: −1.03 - −0.37).

The economic analysis of a multicomponent preventive intervention estimated an average cost of EUR7,282 per patient, which was EUR140 per patient more expensive than usual care. The incremental cost-effectiveness ratio was EUR21,391 per quality-adjusted life-year, which is below the acceptability threshold used in Spain. The literature review yielded two economic evaluations that estimated the cost effectiveness of a multicomponent intervention in the United Kingdom and found that the multicomponent intervention was a dominant strategy.

This meta-analysis suggests that multicomponent interventions and dexmedetomidine are effective in reducing the incidence of delirium in hospitalized patients and that multicomponent interventions could be a cost-effective strategy in Spain.