Impact of Intensive Care Unit Type and Organizational Factors on Mortality in Patients Transferred from Internal Medicine Services to the Intensive Care Unit: A Prospective Cohort Study

Background: Clinical deterioration is common among patients hospitalized in Internal Medicine wards and frequently results in the need for Intensive Care Unit (ICU) admission. Limited ICU bed capacity may lead to delays or interhospital transfers, potentially affecting outcomes. This study evaluated the association between ICU follow-up location and mortality, and its relationship with organizational processes. Methods: In this prospective cohort study, adult patients (≥18 years) requiring ICU consultation between March 2024 and February 2025 were consecutively enrolled. Demographic characteristics, comorbidities, ICU indications, waiting times, mortality, and ICU type were recorded. Patients were categorized into three groups: Internal Medicine ICU, Anesthesiology ICU, and external ICU. The primary endpoint was overall ICU mortality. Multivariable logistic regression was performed to identify independent predictors. Results: A total of 331 patients were included (median age 64 years; 59.2% male). Of these, 34.7% were admitted to the Internal Medicine ICU and 24.5% to the Anesthesiology ICU, and 40.8% were transferred externally. Seven-day, 14-day, and overall ICU mortality were significantly higher in the external ICU group (all p < 0.001). External ICU transfer was independently associated with mortality (OR 3.26; 95% CI 1.70–6.26; p < 0.001), along with pre-ICU intubation and sepsis. Conclusions: Mortality is high among deteriorating Internal Medicine patients requiring ICU care. External ICU transfer is strongly associated with increased mortality, highlighting the potential relevance of ICU accessibility and continuity of care.