Factors associated with hospitalization from a geriatric short-stay unit (OBI-GER): a retrospective cohort study

Background: Geriatric Short-Stay Observation Units (G-SSU) are specialized units designed to improve care for older adults within the emergency department (ED). At our hospital, the Osservazione Breve Intensiva Geriatrica (OBI-GER) was established as a dedicated G-SSU. Aims: This study aims to characterize the clinical profile of older adults admitted to OBI-GER and identify factors associated with hospitalization within the first 24 h of admission. Methods: Retrospective, single-center study including individuals aged ≥ 75 years, admitted to OBI-GER between August 2023 and August 2024, with frailty and/or delirium during ED stay. Multivariable logistic regression model with stepwise selection was used to assess associations between hospitalization and clinical, functional, laboratory, and organizational variables. Results: Overall, 353 patients (mean age 86.8 ± 5.5 years, 47.9% male) were included, of whom 109 (30.8%) required hospitalization. The cohort exhibited moderate frailty (median Clinical Frailty Scale = 6, IQR 6–7) and a considerable comorbidity burden (median Charlson Comorbidity Index [CCI] = 6, IQR 5–8), along with a high prevalence of dementia (45%) and polypharmacy (mean 7.1 ± 3.4 medications). Independent risk factors for hospitalization included higher CCI (OR 1.19, 95% CI 1.05–1.35), delirium on the first day of OBI-GER (OR 2.03, 95% CI 1.13–3.64), frequent faller profile (OR 2.66; 95% CI 1.38–5.12), and lower hemoglobin levels at ED admission (OR 0.89, 95% CI 0.79–0.99). Conclusions: Despite their clinical complexity, only one-third of patients admitted to OBI-GER required hospitalization. CCI, delirium, fall history, and hemoglobin levels may serve to stratify hospitalization risk and optimize patient selection for G-SSU.