Respiratory Rate Oxygenation (ROX) Index for Predicting the Success of High-flow Nasal Cannula (HFNC) Therapy in Pediatric Patients with Pneumonia

Abstract

Background: Pneumonia is a major cause of morbidity and mortality among children worldwide. Acute respiratory distress resulting from pneumonia often requires support with High-flow nasal cannula (HFNC) therapy. However, a subset of patients does not adequately respond to HFNC, making early identification of potential treatment failure crucial to prevent delayed escalation of care. The ROX index has emerged as a potential early predictor and may help identify pediatric patients at increased risk of HFNC failure.
Objective: To determine the optimal ROX index cut-off for predicting HFNC success among pediatric pneumonia patients in Satuek Hospital.
Methods: A retrospective observational study was conducted in pediatric pneumonia patients aged 1 month – 15 years old who received HFNC between September 1^st, 2024 and September 30^th, 2025. Data were analyzed using descriptive statistics and ROC curve analysis to evaluate the predictive performance of the ROX index.
Results: A total of 175 patients were included; 167 (95.4%) had successful HFNC therapy, while 8 (4.6%) failed. ROX index values were significantly higher in the success group at all time points. ROC curve analysis demonstrated that a ROX index > 4.7 was associated with treatment success, with AUC 0.998 (95% CI 0.990–1.000) sensitivity 98.2% and specificity 100%.
Conclusion: The ROX index at 6 hours after initiating HFNC is a highly accurate predictor of treatment success in pediatric patients with pneumonia. Incorporating this index into clinical practice may enhance early decision making and reduce the risk of delayed intubation.