Incidence, predictors and health outcomes of delirium in very old hospitalized patients: a prospective cohort study

BACKGROUND: Delirium is a common complication that leads to poor health outcomes in older patients undergoing treatment. Due to severe consequences, early recognition of high-risk patients and risk factors for delirium are crucial in the prompt initiation of prevention measures. However, research in medically hospitalized patients aged ≥80 years remains limited. This study aimed to determine the incidence, predictors and health outcomes of delirium in very old (aged ≥80 years) hospitalized patients in China. METHODS: A prospective study was conducted in individuals aged ≥80 years admitted to geriatric departments. Potential risk factors were assessed within 24 h after hospital admission. Screening for delirium was performed on admission and every 48 h thereafter for 14 days and assessed if acute mental status changes were observed. During hospitalization, health outcomes were recorded daily. RESULTS: Incident delirium occurred in 109 of 637 very old hospitalized patients (17.1%). The independent predictors of delirium in hospitalized patients aged 80 and over were cognitive function impairment [OR 17.42, 95% CI:(7.47–40.64)], depression [OR 9.30, 95% CI: (4.59–18.84)], CCI ≥ 5 [OR 4.21, 95% CI: (1.48–12.01)], sleep deprivation [OR 3.89, 95% CI: (1.71–8.82)], infection [OR 3.33, 95% CI: (1.70–6.54)], polypharmacy (≥5 medications) [OR 2.85, 95% CI: (1.51–5.39)], constipation [OR 2.58, 95% CI: (1.33–5.02)], and emergency admission [OR 2.13, 95% CI: (1.02–4.45)]. Patients with delirium had significantly longer hospital stays(P < 0.001) and higher percentages of physical restraint use(P < 0.001) and falls (P = 0.001) than those without delirium,. CONCLUSION: The incidence of delirium was high in hospitalized patients aged ≥80 years admitted to the geriatric department and was associated with prolonged hospital stay and higher rates of physical restraint use and falls. In this population, the most important independent risk factors for incident delirium were cognitive function impairment and depression. Health care professionals should recognize and initiate interventions for delirium early in geriatric patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-022-02932-9.