Delirium in the Intensive Care Unit: Incidence, Risk Factors, and Impact on Outcome

Background: The incidence and risk factors for delirium vary among studies. Objective: We aimed to determine the incidence, risk factors, and impact on outcome of delirium in a medical Intensive Care Unit (ICU) in Tunisia using a prospective observational study. Patients: All consecutive patients admitted to the ICU between May 2012 and April 2013 were included if they were aged more than 18 years and had an ICU stay of more than 24 h. Patients who had a cardiac arrest or have a history of dementia or psychosis were excluded. Patients eligible for the study were evaluated by the medical staff to detect delirium using the CAM-ICU. Results: A total of 206 patients were included, 167 did not present delirium and 39 (19%) were analyzed for delirium. Delirious patients had a significantly longer duration of mechanical ventilation (10 days[6-20] vs. 2 days[0-7]) respectively and length of stay in ICU (21.5 days [10.5-32.5] vs. 8 days [5-13]), with no impact on mortality. Delirium was associated with high incidence of unintentional removal of catheters (39% vs. 9%; P < 0.0001), endotracheal tubes (18% vs. 1%; P < 0.0001), and urinary catheters (28% vs. 2%, P < 0.0001). In multivariable risk regression analysis, age (odds ratio [OR] = 4.1, 95% confidence interval [CI]: 1.39-12.21; P = 0.01), hypertension (OR = 3.3, 95% CI: 1.31-8.13; P = 0.011), COPD (OR = 3.5, 95% CI: 1.47-8.59; P = 0.005), steroids (OR = 2.8, 95% CI: 1.05-7.28; P = 0.038), and sedation (OR = 5.4, 95% CI: 2.08-13.9; P < 0.0001) were independent risk factors for delirium. We did not find a relationship between delirium and mortality. Conclusion: Delirium is frequent in the ICU and is associated with poor outcome. Several risk factors for delirium are linked to intensive care environment.