Determinants of ICU Outcomes in Fully Active Patients Before Critical Illness

Aim: To investigate ICU outcomes and early mortality predictors in fully active patients prior to critical illness, a population often considered resilient, yet underrepresented in outcome studies. Materials and Methods: This retrospective cohort study included 139 patients admitted to the medical ICUs of a tertiary hospital between November 2022 and February 2025. Only patients with preserved pre-ICU performance status [Eastern Cooperative Oncology Group (ECOG)≤1 or Clinical Frailty Scale (CFS)≤3] were included. Demographics, comorbidities, admission diagnoses, severity scores (Acute Physiology and Chronic Health Evaluation II [APACHE-II], Sequential Organ Failure Assessment [SOFA]), interventions, and laboratory parameters were recorded. Logistic regression was used to identify the independent predictors for ICU mortality. Results: The ICU mortality rate was 16.5% in fully active critically ill patients. Non-survivors had significantly higher APACHE II and SOFA scores, abnormal laboratory findings, and a greater requirement for mechanical ventilation and renal replacement therapy. Cardiac arrest prior to admission and concominant septic shock were more frequently in non-survivors. ICU admission from inpatient wards (OR 5.69,p=0.023), cardiac arrest before ICU admission (OR 33.45,p=0.002), pulmonary disease as a comorbidity (OR 15.19,p=0.002), concomitant septic shock (OR 5.08,p=0.032), and acute kidney injury (AKI)(OR 10.02,p=0.032) were independent risk factors for ICU mortality, Moreover, SOFA and APACHE II scores showed strong discriminative ability for ICU mortality (AUCs:0.916 and 0.873). Conclusion: Although fully active before critical illness, these patients are not immune to poor ICU outcomes. Our findings highlight that specific clinical presentations like septic shock, cardiac arrest, and AKI carry substantial prognostic value, even in patients considered low-risk by baseline performance.