Characterization of Delirium in an Intensive Care Unit: Real-World Data Based on the Application of the Confusion Assessment Method.

Introduction Delirium is a neuropsychiatric syndrome of acute onset characterized by disturbances in attention, awareness, and cognition. It is common in intensive care units (ICUs), and the Confusion Assessment Method for the ICU (CAM-ICU) is the most widely used bedside instrument for its detection. Methods We conducted a retrospective, observational, single-centre study of all patients admitted to the ICU of a Portuguese community hospital, Unidade Local de Saúde do Alto Minho (ULSAM), between January 1, 2021, and December 31, 2022. Delirium was defined as at least one positive CAM-ICU assessment during the ICU stay. Sociodemographic data, comorbidities, admission characteristics, severity scores (Acute Physiology and Chronic Health Evaluation II (APACHE II), Simplified Acute Physiology Score (SAPS), Sequential Organ Failure Assessment score (SOFA)), and outcomes were compared between patients with and without delirium using chi-square, Mann-Whitney U, and multivariable logistic regression. Results Of 788 ICU admissions (742 patients), 66 (8.4%) had at least one positive CAM-ICU assessment. Patients with delirium were older (median 71 vs 68 years, p=0.021) and had higher APACHE II, SAPS, and SOFA scores, longer ICU stay (median 8 vs 3 days, p<0.001), and a higher rate of invasive mechanical ventilation among those with known ventilation status (n=40/64, 62.5% vs n=279/692, 40.3%, p=0.001) than patients without delirium. In multivariable logistic regression, older age (OR 1.03, p=0.017) and male sex (OR 3.09 relative to female, p=0.001) were independently associated with delirium. Conclusions Delirium affected a modest but clinically important proportion of ICU admissions in this cohort and was associated with older age, male sex, greater severity of illness, and longer, more complicated ICU stays. These findings support the need for continued systematic CAM-ICU screening and multidisciplinary delirium-prevention strategies.