Logistic regression with stepwise selection procedure for each reversibility criterion
| Variables# | OR (95% CI) | p-value |
| ΔFEV1 ≥12% and ≥200 mL | ||
| Sex | 0.610 (0.538–0.691) | <0.0001 |
| Age yrs | 0.978 (0.971–0.984) | <0.0001 |
| Smoking history pack-yrs | 1.003 (1.001–1.005) | 00.0006 |
| SGRQ | 0.985 (0.982–0.989) | <0.0001 |
| FEV1 | 0.982 (0.978–0.987) | <0.0001 |
| ΔFEV1 ≥15% | ||
| Sex | 1.371 (1.191–1.578) | <0.0001 |
| Smoking history pack-yrs | 1.003 (1.001–1.005) | 0.0135 |
| SGRQ | 0.984 (0.981–0.988) | <0.0001 |
| FEV1 | 0.926 (0.921–0.931) | <0.0001 |
| ΔFEV1 ≥10% pred | ||
| Sex | 1.314 (1.159–1.490) | <0.0001 |
| Smoking history pack-yrs | 1.003 (1.001–1.005) | 0.0063 |
| SGRQ | 0.986 (0.983–0.990) | <0.0001 |
| FEV1 | 0.988 (0.983–0.992) | <0.0001 |
An event in the definition of the odds ratio (OR) is a responsive patient according to one of the reversibility criteria. The ORs for the continuous variables (age, percentage predicted forced expiratory volume in one second (FEV1), St George’s Respiratory Questionnaire (SGRQ) total score and smoking history) are calculated according to a one-unit increase in these variables. CI: confidence interval; Δ: change; % pred: % predicted. #: selected from age, sex (female versus male), smoking status, smoking history, chronic obstructive pulmonary disease duration (in years), baseline percentage predicted FEV1 before bronchodilators and SGRQ total score. Variables with a p-value of <0.05 were kept in the model.