What percentage of ICU patients are at risk for delirium?

• A. 25-40%
• B. 66%-90%
• C. 5-15%
• D. 100%

Answer: (B)

Delirium in the ICU is extremely common because critical illness brings many risk factors that disrupt brain function—severe illness, hypoxia, metabolic and electrolyte disturbances, sleep disruption, immobulation, polypharmacy, and especially sedatives and mechanical ventilation. Because of these factors, a large majority of ICU patients will experience delirium during their stay, with many studies reporting roughly two-thirds to most patients being affected. The option that aligns with this high prevalence is in the range of about 66% to 90%, which reflects the extensive risk in ICU populations. The other ranges underestimate the reach, and claiming everyone is affected is not accurate. This high prevalence is why routine delirium screening and prevention/management strategies are essential in critical care.