Persistently ≥2% | Intermittent | Persistently <2% | ANOVA p-value | |
Subjects n | 554 | 728 | 201 | |
Age years | 64±7 | 62±7 | 62±7 | 0.025 |
Male sex | 68 | 64 | 56 | 0.007 |
Smoking history pack-years | 47±26 | 47±26 | 48±30 | 0.810 |
Current smokers | 30 | 36 | 42 | 0.004 |
Post-bronchodilator FEV1 L | 1.45±0.51 | 1.37±0.52 | 1.33±0.51 | 0.003 |
Post-bronchodilator FVC L | 3.20±0.84 | 3.05±0.91 | 3.01±0.96 | 0.005 |
FEV1 % predicted | 51±15 | 49±16 | 48±15 | 0.009 |
Post-bronchodilator FEV1/FVC % | 46±12 | 45±11 | 45±11 | 0.445 |
BMI kg·m−2 | 27±5 | 27±6 | 26±6 | 0.190 |
Fat free mass index kg·m−2 | 53±12 | 52±13 | 50±13 | 0.009 |
6MWD m | 395±116 | 385±115 | 377±127 | 0.142 |
Emphysema by CT (LAA%) | 17±12 | 17±12 | 18±12 | 0.486 |
Oxygen saturation % | 94.9±3.1 | 94.9±2.5 | 94.7±2.5 | 0.676 |
SGRQ total Score | 44±18 | 47±18 | 49±19 | 0.002 |
FACIT fatigue score | 37±10 | 36±10 | 36±10 | 0.106 |
mMRC score | 1.4±1.0 | 1.6±1.0 | 1.7±1.1 | 0.006 |
BODE index | 2.6±1.9 | 2.9±2.0 | 3.2±2.2 | 0.001 |
WBCs ×109 L−1 | 7.5±2.0 | 7.9±2.1 | 8.1±2.2 | <0.001 |
Exacerbation rate# | 0.75±1.18 | 0.86±1.23 | 0.85±1.09 | 0.232 |
COPD hospitalisation rate¶ | 0.13±0.47 | 0.18±0.53 | 0.18±0.57 | 0.245 |
Cardiovascular disease | 30 | 33 | 32 | 0.679 |
History of osteoporosis | 14 | 11 | 11 | 0.428 |
Diabetes | 11 | 8 | 9 | 0.272 |
GORD | 26 | 25 | 27 | 0.840 |
Statin use | 34 | 28 | 27 | 0.094 |
Inhaled corticosteroid use | 89 | 92 | 92 | 0.362 |
Oral corticosteroid use | 0 | 1 | 0 | n/a |
IL-6 pg·mL−1 | 1.9 (0.4–4.2) | 1.9 (0.4–4.0) | 2.2 (0.6–5.1) | 0.476 |
IL-8 pg·mL−1 | 6.2 (2.8–11.2) | 7.0 (3.5–12.4) | 8.3 (4.2–14.9) | 0.004 |
Fibrinogen mg·dL−1 | 443 (384–511) | 442 (387–507) | 443 (393–510) | 0.951 |
Club cell protein 16 ng·mL−1 | 5.4 (3.8–7.3) | 4.7 (3.4–6.5) | 4.7 (3.1–6.4) | <0.001 |
SP-D ng·mL−1 | 123 (8–168) | 115 (84–162) | 122 (87–174) | 0.224 |
CRP mg·L−1 | 3.0 (1.5–6.1) | 3.2 (1.7–7.3) | 3.5 (1.6–7.0) | 0.147 |
CCL-18 ng·mL−1 | 112 (87–140) | 102 (79–132) | 101 (81–123) | <0.001 |
Longitudinal Changes | ||||
FEV1 decline mL·year−1 | 31±48 | 35±44 | 30±42 | 0.209 |
COPD exacerbations PPPY+ | 1.06±1.18 | 1.15±1.27 | 1.07±1.31 | 0.277 |
COPD hospitalisations PPPY+ | 0.16±0.38 | 0.22±0.49 | 0.23±0.45 | 0.283 |
6MWD change over 3 years m | -15±90 | -20±103 | -20±87 | 0.626 |
Emphysema by CT (LAA%) change§ | 1.3±4.5 | 1.8±4.9 | 2.7±5.0 | 0.010 |
SGRQ total score change+ | 0.2±12.5 | 1.6±12.8 | -1.6±14.3 | 0.007 |
Date are presented as mean±sd, % or median (interquartile range), unless otherwise stated. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; BMI: body mass index; 6MWD: 6-min walking distance; CT: computed tomography; LAA%: % low-attenuation areas; SGRQ: St George’s Respiratory Questionnaire; FACIT: Functional Assessment of Chronic Illness Therapy; mMRC: modified Medical Research Council; BODE: BMI, airflow obstruction, dyspnoea, exercise capacity; WBCs: white blood cells; COPD: chronic obstructive pulmonary disease; GORD: gastro-oesophageal reflux disease; IL: interleukin; SP-D: surfactant protein D; CRP: C-reactive protein; CCL-18: chemokine ligand 18; PPPY: per person per year; n/a: not applicable. #: in the year prior to entry; ¶: in the prior year; +: over 3 years; §: change in LAA% reflects year 3 value minus baseline value.