Table 1.
Baseline characteristics of participants with incident COPD
| Baseline characteristics | COPD cases retrieved for adjudicationa | COPD cases not adjudicated | All COPD cases |
|---|---|---|---|
| N | 1,069 | 10,730 | 11,799 |
| Age, years (mean ± SD) | 62.9±9.2 | 62.4±13.9 | 62.4±12.8 |
| Female (%) | 46.3 | 50.2 | 50.7 |
| Urban (%) | 37.0 | 13.5 | 15.1 |
| Follow-up time, years (mean ± SD) | 3.7±1.7 | 4.7±6.3 | 4.6±4.9 |
| Highest education completed (%) | |||
| None/primary school | 61.6 | 58.8 | 57.6 |
| Middle/high school | 34.7 | 36.9 | 38.4 |
| College/university | 3.7 | 4.2 | 4.0 |
| Annual household income (%) | |||
| <10,000 (Yuan) | 11.6 | 12.2 | 11.8 |
| 10,000–34,000 (Yuan) | 78.4 | 72.6 | 73.9 |
| ≥35,000+ (Yuan) | 10.0 | 15.1 | 14.3 |
| Smoking status (%) | |||
| Current regular | 25.2 | 27.7 | 26.9 |
| Ex-regular | 10.9 | 7.8 | 7.9 |
| Never regular | 63.9 | 64.6 | 65.1 |
| Height, cm (mean ± SD) | 156.3±6.6 | 156.2±9.5 | 156.2±8.7 |
| BMI, kg/m2 (mean ± SD) | 22.7±4.3 | 23.1±9.2 | 23.1±8.2 |
| Self-reported health status (%) | |||
| Poor | 32.1 | 21.4 | 23.0 |
| Fair | 39.7 | 46.2 | 45.5 |
| Good | 17.4 | 21.1 | 19.9 |
| Excellent | 10.7 | 11.3 | 11.5 |
| Lung function (mean ± SD) | |||
| FEV1 (L) | 1.46±0.65 | 1.81±1.47 | 1.80±1.47 |
| FVC (L) | 1.92±0.75 | 2.25±1.57 | 2.25±1.49 |
| FEV1/FVC (%) | 74.8±14.5 | 78.9±24.5 | 78.6±24.4 |
| COPD severityb (%) | |||
| Grade 1–2 | 7.3 | 5.0 | 6.1 |
| Grade 3 | 3.1 | 2.4 | 2.5 |
| Grade 4 | 7.9 | 6.9 | 6.4 |
| Grade 5 | 21.4 | 10.8 | 11.9 |
| Self-reported comorbidity (%) | |||
| Hypertension | 12.0 | 11.9 | 11.5 |
| IHD | 6.2 | 4.0 | 4.1 |
| Diabetes | 2.9 | 2.7 | 2.7 |
| Stroke/TIA | 1.4 | 1.7 | 1.7 |
Notes:
Standardized for age, sex, and regions;
data from baseline lung function (2004–2008): COPD Grade 1–2= FEV1/FVC <LLN and (z-score of FEV1 −2.5 to 1.0); Grade 3= FEV1/FVC <LLN and (z-score of FEV1 −3.0 to −2.5); Grade 4= FEV1/FVC <LLN and (z-score of FEV1 −3.5 to −3.0); Grade 5= FEV1/FVC <LLN and (z-score of FEV1 <−3.5); and P-values between two groups for all characteristics are <0.05. Eventually, medical records of 1,069 participants were retrieved for adjudication.
Abbreviations: SD, standard deviation; BMI, body mass index; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; IHD, ischemic heart diseases; TIA, transient ischemic attack; LLN, lower limit of normal.