Advantages and limitations of the ROX index

Dear editor We have read with interest the study by Vega et al1 published in the latest issue of the journal, where the authors propose the ROX index as a predictor of failure of high-flow nasal cannula (HFNC) therapy in patients with pneumonia due to SARS-CoV-2, and we would like to share some considerations on the advantages and disadvantages of using this index.