Smoking and occupational exposure as independent and joint associations with COPD
| Cigarette smoking/occupational VGDF exposure | n | Risk of COPD | Excess risk | Unadjusted OR | Adjusted OR* (95% CI) |
| Any COPD, emphysema or chronic bronchitis, with or without concomitant asthma (231 cases) | |||||
| Never/no | 530 | 0.02 | – | 1.00 | – |
| Never/yes | 302 | 0.08 | 0.06 | 4.29 | 5.63 (2.60 to 12.20) |
| Pack years low/no | 248 | 0.07 | 0.05 | 3.59 | 3.96 (1.77 to 8.89) |
| Pack years low/yes | 279 | 0.18 | 0.16 | 11.63 | 15.68 (7.62 to 32.28) |
| Pack years high/no | 186 | 0.15 | 0.13 | 8.83 | 10.44 (4.91 to 22.20) |
| Pack years high/yes | 338 | 0.31 | 0.29 | 23.11 | 32.04 (15.92 to 64.47) |
| Any COPD excluding chronic bronchitis alone (155 cases) | |||||
| Never/no | 525 | 0.01 | – | 1.00 | – |
| Never/yes | 290 | 0.04 | 0.03 | 4.10 | 5.47 (1.85 to 16.16) |
| Pack years low/no | 239 | 0.03 | 0.02 | 3.14 | 3.50 (1.10 to 11.18) |
| Pack years low/yes | 253 | 0.10 | 0.09 | 11.40 | 15.93 (5.85 to 43.34) |
| Pack years high/no | 180 | 0.12 | 0.11 | 13.74 | 16.47 (6.07 to 44.74) |
| Pack years high/yes | 320 | 0.27 | 0.26 | 38.22 | 54.11 (20.94 to 139.87) |
This table includes only the 1883 respondents who gave complete smoking and VGDF data (participants with missing data for JEM classification were included). For the any COPD excluding chronic bronchitis alone analysis, those with chronic bronchitis have been completely excluded (not included with referents) to avoid misclassification bias (n=1807).
↵* ORs adjusted for age and sex.
JEM, job exposure matrix; pack years low, 20 pack years or less; Pack years high, more than 20; VGDF, vapours, gases, dusts or fumes.