Table 2. Changes in COPD variables after the index time.
| Variable | Triple (n=109) | Step-down (n=39) | p-value for the change after the IT | ||
|---|---|---|---|---|---|
| Just before the IT* | Just after the IT* | Just before the IT* | Just after the IT* | ||
| Pre-bronchodilator FEV1, L | 1.31±0.44 | 1.28±0.46 | 1.49±0.38 | 1.48±0.36 | 0.752 |
| Pre-bronchodilator FEV1, % predicted | 44.75±13.67 | 44.53±14.45 | 49.40±11.80 | 49.33±11.01 | 0.485 |
| IC, % predicted | 77.51±22.15 | 76.05±24.19 | 76.56±21.33 | 75.60±21.28 | 0.470 |
| RV/TLC, % predicted | 48.66±11.51 | 49.60±11.38 | 42.23±11.89 | 43.83±12.12 | 0.983 |
| MMRC | 1.86±1.14 | 1.94±1.09 | 1.87±1.11 | 1.72±1.05 | 0.146 |
| 6MWD, m | 422.45±86.04 | 413.07±99.16 | 432.27±101.86 | 403.85±105.52 | 0.019 |
| SGRQ total score | 36.21±17.53 | 36.91±19.22 | 30.81±15.26 | 35.25±17.10 | 0.037 |
| Exacerbation frequency/yr | 0.78±0.99 | 0.72±1.00 | 0.36±0.58 | 0.28±0.65 | 0.266 |
Values are presented as the mean±standard deviation.
p-values were obtained by analysis of covariance (ANCOVA) for continuous variables and logistic regression analysis for categorical variables. All analyses were adjusted for baseline FEV1, gender, age, smoking status, computed tomography emphysema index, and the time intervals when the variables were measured.
*"Just before the IT" refers to the most recent results before the IT and "Just after the IT" refers to the first results collected after the IT. MMRC was measured every 3 months, pre-bronchodilator FEV1 was measured every 6 months, and IC, RV/TLC, 6MWD, SGRQ total score, and exacerbation/year were measured every 12 months.
COPD: chronic obstructive pulmonary disease; IT: index time; FEV1: forced expiratory volume in 1 second; IC: inspiratory capacity; RV: residual volume; TLC: total lung capacity; MMRC: modified Medical Research Council; 6MWD: 6-minute walk distance; SGRQ: St. George's Respiratory Questionnaire.