A meta-analysis of critically ill patients reveals several potential risk factors for delirium

To investigate potential risk factors for delirium in critically ill patients through a meta-analysis of clinical observational studies.

A literature search was conducted of MEDLINE and Embase databases. Studies that reported risk factors for delirium in a critical care setting were included. Data were independently extracted by two reviewers and pooled using a fixed-effect or random effects model according to the result of a heterogeneity test.

Twenty-five studies were included. The combined odds ratio (95% confidence interval) for each potential risk factor estimated by meta-analysis was as follows (univariate/multivariate): alcohol use, 1.47 (0.79-2.72)/2.34 (1.56-3.49); smoking, 1.01 (0.81-1.25)/1.61 (0.83-3.10); hypertension, 1.64 (1.30-2.06)/1.98 (1.44-2.72); age (per year), 1.03 (1.001-1.05)/1.04 (1.02-1.05); age >65 years, 2.52 (1.55-4.10)/2.59 (1.93-3.47); mechanical ventilation, 3.09 (1.43-6.66)/4.51 (1.41-14.39); and Acute Physiology and Chronic Health Evaluation (APACHE) II score (per point), 1.13 (1.06-1.21) (multivariate only). There was no evidence of publication bias except for APACHE II score.

Age, history of hypertension, clinical use of mechanical ventilation and higher APACHE II score are associated with increased risk of delirium in critically ill patients.