Clinical characteristics and risk factors associated with consultation‐confirmed delirium in hospitalized patients

Aim Delirium, a serious neuropsychiatric hospitalization complication, is a manifestation of underlying neurocognitive vulnerability rather than an acute event. In Japan, a nationwide medical policy mandates early hospital‐wide delirium risk screening to evaluate predefined risk factors in inpatient populations. We aimed to identify demographic and clinical factors independently associated with referral‐based, consultation‐confirmed delirium. Methods We conducted a retrospective observational study of consecutive hospitalized patients at Nara Medical University Hospital between June 2022 and November 2023, without exclusion criteria. Delirium risk factors were assessed within 3 days of admission using a standardized checklist based on national criteria. Delirium was diagnosed following specialist consultation according to the International Classification of Diseases, 10th Revision (ICD‐10), and the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision criteria. Logistic regression analyses were performed to identify independent association with consultation‐confirmed delirium. Results Among 20,980 patients (mean age, 67.1 ± 17.0 years; males, 55.0%), 209 (1.0%) were diagnosed with delirium following specialist consultation. Overall, 56.4% met at least one predefined risk criterion at admission. In multivariable analyses adjusted for age and sex, dementia (odds ratio [OR], 3.995; 95% confidence interval [CI], 2.647–6.029), history of delirium (OR, 3.649; 95% CI, 2.158–6.170), and heavy alcohol use (OR, 1.648; 95% CI, 1.002–2.710) were independently associated with consultation‐confirmed delirium. Conclusions In this large cohort evaluated under a nationwide screening framework, consultation‐confirmed delirium was independently associated with baseline neurocognitive vulnerability (dementia and history of delirium) and heavy alcohol use, rather than chronological age alone, supporting vulnerability‐focused risk stratification in routine clinical practice.