Fig. 8

Receiver operating characteristic curves for risk factors of combined diaphragm function indexes in predicting AECOPD. The AUC of chest wall motion combined with the diaphragm thickening fraction was 0.901, 95% CI (0.822–0.980), P < 0.001. The sensitivity and specificity were 90.3% and 83%, respectively. AECOPD, acute exacerbation of chronic obstructive pulmonary disease; AUC, area under the curve; CI, confidence interval