Figure 2.

Receiver operating-characteristic curves showing predictive value of three different scores in predicting COPD (FEV₁/FVC < 0.7) and severe COPD (FEV₁/FVC < 0.7 and FEV₁% predicted <50): dyspnea score (short of breath doing physical activities in the clinical COPD questionnaire), summing up of dyspnea score and pack-years (0–10, 1; 10–20, 2; 20–40, 3; ≥40, 4), and summing up of dyspnea score, pack-years, and chest-finding score (addition of wheezes, 1; diminished breath sound, 2; hyperresonance to percussion, 3).

Abbreviations: COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; CI, confidence interval; AUC, area under the curve.