Epidemiology of Delirium in Elderly Inpatients: Prevalence and Associated Factors in a Sri Lankan Tertiary Hospital

Background: Delirium is a common yet under-recognised neuropsychiatric syndrome among older inpatients, associated with substantial morbidity, mortality, and healthcare burden. As hospital admissions among older adults continue to rise globally, understanding the prevalence and contributing factors is essential to improving geriatric care. Aims: To estimate the prevalence and associated factors of delirium among surgical and medical inpatients aged 65 years or older at Teaching Hospital Anuradhapura, Sri Lanka. Methods: A descriptive cross-sectional study was conducted among patients aged 65 and older admitted to general medical and surgical wards at the Teaching Hospital, Anuradhapura. Systematic random sampling was applied using ward admission registries. Dilirium screening was performed using the Confusion Assessment Method (CAM), followed by diagnostic confirmation with clinical DSM-5 criteria. Potential determinants of delirium were identified using binary logistic regression. Results: Of 233 older adult inpatients, the majority were male (54%, n = 126), married (95%, n = 223), unemployed (90%, n = 210), and 48% (n = 110) had at least a primary-level education. The overall prevalence of delirium was 18% (95% CI = 13.3–33.6%). It was 20.3% (95% CI = 14.8–25.2) in general medical wards, and 11.5% (95%CI = 6.88–15.1) in general surgical wards. Hypoactive delirium was the most common subtype (40.5%, n = 17), followed by hyperactive (33.3%, n = 14) and mixed types (26.2%, n = 11). Of those diagnosed with delirium, 54.8% (n = 23) were females, the mean age was 76.6 (SD = 6.6), and the mean duration of hospital stay was 6.7 days (SD = 6.1). Multivariable logistic regression analysis identified following independent associated factors; age > 65 years (OR = 1.19, 95%CI = 1.08–1.35, P = 0.002), current infections (OR = 10.17, 95%CI = 3.1-41.41,P < 0.001), catheterization (OR = 3.85, 95%CI = 1.16 -13, P = 0.027), nasogastric feeding (OR = 49.99, 95%CI = 5-826.64, P = 0.002), assisted ventilation (OR = 6.75, 95%CI = 1.74–28.32, P = 0.007), history of delirium (OR = 9.44, 95%CI = 2.45–41.08, P = 0.002), longer hospital stay (OR = 1.10, 95%CI = 1.003–1.21, P = 0.042) and sleep disturbances (OR = 6.44, 95%CI = 2.02–23.97, P = 0.003). Conclusions: Nearly one in five older inpatients in medical and surgical wards had delirium. The associations observed with infection, invasive procedures, prior delirium, prolonged hospital stay, and sleep disturbances. These findings highlight the need for routine screening, early identification, and targeted prevention strategies in geriatric inpatient care settings.