Prognostic Factors for Acute Exacerbation of Interstitial Pneumonia: Utility of the ROX Index

<bold>Background:</bold> The ROX index (SpO2/FiO2/RR) is a useful predictor of the success of high-flow nasal cannula (HFNC) therapy for acute respiratory failure. However, its applicability as a prognostic factor for patients with acute exacerbation of interstitial pneumonia (AE-IP) remains unclear. <bold>Methods:</bold> We retrospectively investigated the ROX index and 30-day mortality in 92 patients with AE-IP who received HFNC from April 2016 to June 2023 at our institution. <bold>Results:</bold> Patient characteristics included a median age of 67 years, 73% male, 38% with UIP pattern, and WBC/LDH of 12100/425. The association between 30-day mortality and ROX index at 0 hours (ROX 0) and 12 hours (ROX 12) after HFNC initiation was observed with odds ratios (OR) of 0.80 (95% CI, 0.63-1.00) and 0.66 (95% CI, 0.50-0.85), respectively. Multivariate analysis, including UIP pattern, age, LDH, WBC, pre-exacerbation oxygen therapy, and ROX 12, revealed that only ROX 12 was statistically significant in relation to 30-day mortality (OR 0.67; 95% CI, 0.51-0.88). <bold>Conclusion:</bold> The ROX 12 index has the potential to serve as a prognostic factor for AE-IP.