Clinically recognized sepsis in older adults admitted to medical wards: patient characteristics and hospital outcomes from the REPOSI register

Older adults admitted to internal medicine wards represent a growing population at high risk of sepsis, characterized by frailty, multimorbidity, functional impairment and reduced physiological reserve. While sepsis outcomes have been extensively studied in intensive care settings, less is known about prognostic determinants in non-ICU wards. Using data from the Italian REPOSI registry (2009–2023), we analyzed patients aged ≥65 years hospitalized in internal medicine and geriatric wards. Clinically recognized sepsis was identified through documented clinical diagnoses and corresponding ICD-9 codes. Latent Class Analysis (LCA) was used to explore multimorbidity patterns within the sepsis cohort. The primary aim was to evaluate factors associated with in-hospital mortality in older adults with sepsis. Secondary analyses compared baseline characteristics between septic and non-septic cases, assessed in-hospital mortality determinants according to sepsis onset setting (community- vs hospital-acquired), and explored factors associated with prolonged length of stay (LOS) in community-acquired sepsis. Additional descriptive analyses evaluated geographic distribution, infection sources and treatment patterns. Among 8880 patients, 504 (5.7%) had clinically recognized sepsis; more than half were hospital-acquired. In-hospital mortality was high (23.8%) and markedly higher in hospital-acquired sepsis. Two distinct multimorbidity patterns emerged: an oncologic–hepatologic profile and a diffuse chronic multimorbidity profile characterized by cardio–renal–metabolic, respiratory, and neuropsychiatric conditions. In community-acquired sepsis, the chronic multimorbidity profile was independently associated with increased mortality, whereas this association was not observed in hospital-acquired sepsis. Across the cohort, advanced age, functional dependence and hypoalbuminemia emerged as key factors independently associated with in-hospital mortality. Exploratory LOS analyses in community-acquired sepsis showed a modest association between prolonged hospitalization and higher anticholinergic burden. Additional descriptive analyses showed that lower respiratory tract infections were the most frequent source of both community- and hospital-acquired sepsis, while hospital-acquired cases showed greater heterogeneity of infectious sources and treatment patterns. In internal medicine wards, clinically recognized sepsis in older adults may reflect underlying clinical vulnerability rather than an isolated acute event. Multimorbidity patterns and geriatric-related clinical dimensions appear to influence outcomes, particularly in community-acquired sepsis. Integrating multimorbidity, nutritional and functional assessments into sepsis evaluation may improve risk stratification and support more personalized management in older hospitalized patients.