Baseline characteristics
| All (n=10 000) | PREO-POSTO (n=4150) | PREN-POSTN (n=4683) | PREO-POSTN (n=866) | PREN-POSTO (n=301) | P value* | |
| Age, year±SD | 59.6±9 | 63.4±8.5 | 56.4±8.2 | 59.3±8.9 | 59.1±8.9 | 0.72 |
| Female, % (n) | 46.7 (4668) | 43.9 (1823) | 49.4 (2315) | 44.6 (386) | 47.8 (144) | 0.36 |
| Non-white race, % (n) | 32.9 (3287) | 21.6 (895) | 42.9 (2010) | 31.4 (272) | 36.5 (110) | 0.12 |
| BMI, kg/m2±SD | 28.8±6.3 | 27.8±6.1 | 29.7±6.3 | 28.6±6.3 | 29.5±6.4 | 0.023 |
| PPY±SD | 44.3±24.9 | 52.2±27.2 | 37.8±20.8 | 41.9±22.8 | 43.2±24.3 | 0.57 |
| Active smoking, % (n) | 52.8 (5279) | 42.1 (1746) | 60.9 (2853) | 57.4 (497) | 60.8 (183) | 0.33 |
| Chronic bronchitis, % (n) | 19.2 (1922) | 26.5 (1101) | 13.3 (621) | 16.6 (144) | 18.6 (56) | 0.48 |
| Asthma, % (n) | 19.4 (1943) | 25.3 (1049) | 14.4 (674) | 18.5 (160) | 19.9 (60) | 0.59 |
| CAD, % (n) | 6.5 (648) | 9 (375) | 4.4 (207) | 5.4 (47) | 6.3 (19) | 0.67 |
| CHF, % (n) | 3.2 (320) | 4.6 (192) | 2 (96) | 2.3 (20) | 4 (12) | 0.18 |
| DM, % (n) | 13 (1301) | 11.9 (494) | 13.6 (638) | 14.2 (123) | 15.3 (46) | 0.64 |
| HTN, % (n) | 43.2 (4322) | 48.4 (2008) | 39 (1830) | 39.7 (344) | 46.5 (140) | 0.046 |
| OSA, % (n) | 14.6 (1459) | 16 (665) | 13.3 (624) | 14 (121) | 16.3 (49) | 0.39 |
| Stroke, % (n) | 2.6 (258) | 3.4 (139) | 1.9 (90) | 2.1 (18) | 3.7 (11) | 0.19 |
| SaO2,%±SD | 96.1±2.9 | 94.9±3.5 | 97±2.1 | 96.8±2.4 | 96.5±2.5 | 0.15 |
| MMRC±SD | 1.4±1.4 | 1.9±1.5 | 0.9±1.3 | 1±1.3 | 1.3±1.5 | 0.0011 |
| SGRQ±SD | 27.4±22.9 | 37.6±22.7 | 19.5±19.8 | 21.3±20.8 | 27.2±23.1 | <0.001 |
| Post-FEV1, %±SD | 76.3±25.6 | 55.9±22.4 | 92.6±15.4 | 84.7±15.9 | 77.3±17.4 | <0.001 |
| Post-FVC, %±SD | 86.9±18.3 | 81.2±20.3 | 91.4±15.1 | 89±16.7 | 91.6±18.8 | 0.087 |
| BDR, % (n) | 21.5 (2146) | 33.9 (1408) | 9.2 (432) | 19.5 (169) | 45.5 (137) | <0.001 |
| Delta FEV1, %±SD | 5.8±10.3 | 8.8±12.1 | 3±6.6 | 7.7±10.8 | 1.5±15.5 | <0.001 |
| Delta FVC, %±SD | 3.9±12.6 | 7.5±13.2 | 0.9±7.5 | −2.1±9.3 | 17.7±34.4 | <0.001 |
| Emphysema, %±SD†‡ | 7.6±10.6 | 14±12.9 | 2.2±2.8 | 2.9±3.1 | 3.4±5 | 0.45 |
| Gas trapping, %±SD†‡ | 24.2±20.8 | 39.3±20.5 | 10.6±9 | 15±10 | 17.1±12.6 | 0.19 |
| 6-MWD, feet±SD | 1351±399 | 1224±408.2 | 1443±365.3 | 1447±370.1 | 1352±382.3 | <0.001 |
*Comparison between PREO-POSTN and PREN-POSTO using χ2 and Student’s t-test or Wilcoxon rank sum test.
†For emphysema and gas trapping analysis, data were available for 5553 and 4945 subjects, respectively.
‡Gas trapping was measured at functional residual capacity.
6-MWD, 6 min walk distance; BDR, bronchodilator response; BMI, body mass index; CAD, coronary artery disease; CHF, congestive heart failure; Delta FEV1%, % change in FEV1 after bronnchodilator; Delta FVC%, % change in FVC after bronchodilator; DM, diabetes mellitus; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; HTN, hypertension; MMRC, modified Medical Research Council dyspnoea score; OSA, obstructive sleep apnoea; pre-FEV1%, prebronchodilator FEV1% predicted; post-FEV1%, postbronchodilator FEV1% predicted; PPY, pack per year; SaO2, arterial oxygen saturation; SGRQ, St. George’s Respiratory Questionnaire score;6-MWD = 6-min walk distance.
PREN-POSTN: prebronchodilator FEV1/FVC >0.7 and postbronchodilator FEV1/FVC >0.7.
PREN-POSTO: prebronchodilator FEV1/FVC >0.7 and postbronchodilator FEV1/FVC <0.7.
PREO-POSTNO: prebronchodilator FEV1/FVC <0.7 and postbronchodilator FEV1/FVC <0.7.
PREO-POSTN: prebronchodilator FEV1/FVC <0.7 and postbronchodilator FEV1/FVC >0.7.