Prognostic value of the Chelsea critical care physical assessment in immunocompromised critically ill patients: development and validation cohorts

Immunocompromised patients admitted to the intensive care unit (ICU), particularly those with acute respiratory failure, have persistently high mortality. Early identification of patients at risk of death or need for invasive mechanical ventilation (IMV) remains challenging, and commonly used severity scores rely on laboratory data that may not fully reflect functional vulnerability. We evaluated whether the Chelsea Critical Care Physical Assessment (CPAx), a bedside functional scale, provides prognostic information complementary to established severity scores in immunocompromised critically ill patients, and validated these findings in a general ICU population. We conducted a retrospective cohort study including adults (≥ 18 years) with an ICU length of stay of at least 48 h between January 2024 and April 2025. Severity at ICU admission was assessed using the Sequential Organ Failure Assessment (SOFA), Simplified Acute Physiology Score III (SAPS-III), and CPAx in the first 24 h. Functional trajectory during the ICU stay was evaluated using final ICU CPAx assessment, the change in CPAx (ΔCPAx), and the CPAx rate of change, defined as ΔCPAx divided by ICU length of stay. The primary outcome was ICU mortality; the secondary outcome was IMV requirement. Discriminative performance was assessed using the area under the receiver operating characteristic curve (AUC). External validation was performed in a prospective mixed medical–surgical ICU cohort. Among 755 ICU admissions, 540 met inclusion criteria. Among them, 320 survived, and 220 died. The combination of CPAx at ICU admission with SOFA improved discrimination for ICU survival compared with CPAx at ICU admission or SOFA alone [ΔAUC (CI95%) 0.042 (0.015–0.068), p =0.002; 0.060 (0.030–0.090), p <0.001, respectively]. Adding CPAx at ICU admission to SOFA improved discrimination for IMV requirement compared with SOFA alone [ΔAUC (CI95%) 0.071 (0.040–0.102), p <0.001]. These findings were consistent in the external validation cohort. In immunocompromised, critically ill patients, CPAx assessed at ICU admission demonstrated discriminative performance for survival comparable to established severity scores. The combination of CPAx at ICU admission with SOFA improved discrimination for ICU survival compared with CPAx at ICU admission or SOFA alone.