Characteristics of all study participants
| N or mean (SD) | COPD (N) | Prevalence (%) | |
|---|---|---|---|
| Age group, year | |||
| ≤40 | 1318 | 9 | 0.68 |
| 41–60 | 3254 | 188 | 5.78 |
| >60 | 1421 | 324 | 22.80 |
| Sex | |||
| Male | 2959 | 397 | 13.42 |
| Female | 3034 | 124 | 4.09 |
| Education status | |||
| Under primary school | 423 | 48 | 11.34 |
| Primary school | 1557 | 181 | 11.62 |
| Junior high school | 2022 | 193 | 9.55 |
| Senior high school | 1405 | 78 | 5.55 |
| Graduate and above | 586 | 21 | 3.75 |
| Smoking history | |||
| Yes | 2039 | 346 | 16.96 |
| No | 3954 | 175 | 4.42 |
| Occupational exposure | |||
| Yes | 2419 | 291 | 12.03 |
| No | 3574 | 230 | 6.44 |
| Biofuel exposure | |||
| Yes | 2477 | 254 | 10.25 |
| No | 3516 | 267 | 7.59 |
| Family history | |||
| Yes | 469 | 59 | 12.58 |
| No | 5524 | 462 | 8.36 |
| History of childhood pneumonia in the hospital | |||
| Yes | 125 | 22 | 17.60 |
| No | 5868 | 499 | 8.50 |
| Mother smoking during pregnancy | |||
| Yes | 277 | 32 | 11.55 |
| No | 5716 | 489 | 8.55 |
| Mother exposed to second-hand smoking during pregnancy | |||
| Yes | 3008 | 265 | 8.81 |
| No | 2985 | 256 | 8.58 |
| Kitchen ventilation quality | |||
| Bad | 3286 | 296 | 9.01 |
| Common | 2212 | 188 | 8.50 |
| Good | 495 | 37 | 7.47 |
| Environmental tobacco smoking exposure* | |||
| 0 | 3741 | 356 | 9.52 |
| 1 | 1090 | 104 | 9.54 |
| 2 | 1155 | 60 | 5.19 |
| 3 | 7 | 1 | 14.29 |
| Rural and urban distribution | |||
| Rural | 3800 | 378 | 9.95 |
| Urban | 2193 | 143 | 6.52 |
| Lung function outcomes | |||
| FEV1, L | 2.61 (0.7) | – | – |
| FVC, L | 3.21 (0.8) | – | – |
| FEV1%pred, % | 97.63 (16.2) | – | – |
| FVC%pred, % | 99.59 (15.5) | – | – |
| FEV1/FVC, % | 81.45 (9.7) | – | – |
Data were collected from all 5993 participants in the seven clusters.
*Environmental tobacco smoking exposure was defined using two added scores according to exposure at home and at the workplace.