Prognostic performance of APUA, APUA-RO2, and CURB-65 scores in patients with critical pneumonia.

BACKGROUND: Severe pneumonia requiring intensive care unit (ICU) admission is associated with high short-term mortality. Early risk stratification in emergency settings is essential to guide clinical decisions. The APUA and APUA-RO2 scores have been proposed as simplified prognostic tools, but their performance in critically ill pneumonia patients remains unclear. OBJECTIVE: To compare the prognostic performance of APUA, APUA-RO2, and CURB-65 scores in emergency department patients with pneumonia and ICU indications. METHODS: This retrospective, single-center study included adult patients with community-acquired pneumonia who were evaluated for ICU admission in the emergency department between 1 September 2024, and 1 September 2025. Demographic, clinical, and laboratory data were extracted from electronic medical records. APUA, APUA-RO2, and CURB-65 scores were calculated at presentation. The primary outcome was 30-day in-hospital mortality. Discriminative ability was assessed using receiver operating characteristic curves and area under the curve (AUC) analysis. Multivariable logistic regression was performed to identify independent predictors of mortality. RESULTS: Among 191 patients, 121 (63.4%) died within 30 days. Non-survivors had higher respiratory rates, CRP, LDH, creatinine, and pneumonia severity scores (APUA, APUA-RO2, CURB-65; all p < .001). All three scores demonstrated moderate discriminative performance, with AUCs of 0.732 for APUA, 0.765 for APUA-RO2, and 0.697 for CURB-65. Model performance was highest for APUA-RO2 (AUC 0.825, sensitivity 87.6%, specificity 55%). Pairwise AUC comparisons did not reach statistical significance, although APUA-RO2 showed a trend toward better performance. Multivariable analysis confirmed that malignancy and higher pneumonia severity scores were independent predictors of mortality. CONCLUSIONS: All three severity scores demonstrated moderate discriminative ability for predicting 30-day mortality in critically ill pneumonia patients. Among them, APUA-RO2 showed the highest prognostic performance, although its overall discrimination remained moderate. Therefore, these scores may assist, but should not replace, clinical judgment when assessing critically ill patients. Prospective multicenter validation is warranted.