Fig. 3

ROC curve analysis of CD4⁺CD8⁺ T cells%, CAT score, and home oxygen therapy for predicting respiratory failure in patients with acute exacerbation of COPD. COPD, chronic obstructive pulmonary disease; AUC, the area under the curve; Sen, sensitivity; Spe, specificity; Cov, cut-off value; ROC, receiver operating characteristic; CAT, chronic obstructive pulmonary disease assessment test