Results from a series of linear regression models with change in respiratory burden score, with a single exposure variable and also adjusted for baseline respiratory burden score
| Exposure variable | n (%) or mean (SD) | Coefficients from regression model (95% CI) | Coefficient from regression model adjusted for respiratory burden score in 2013 (95% CI) |
| Sex, n (%) | |||
| Female | 3662 (58) | Reference category | Reference category |
| Male | 2688 (42) | 0.040 (−0.04 to 0.12) | −0.07 (−0.14 to 0.005) |
| Age in 2013, mean (SD) | 38.05 (9.45) | 0.00 (−0.004 to 0.004) | 0.002 (−0.001 to 0.006) |
| Education, n (%) | |||
| Elementary school | 756 (12) | Reference category | Reference category |
| Upper secondary | 2311 (36) | −0.45 (−0.18 to 0.04) | −0.11 (−0.23 to 0.006) |
| University | 3103 (49) | −0.4 (−0.17 to 0.09) | −0.13 (−0.25 to −0.02) |
| Other and missing | 180 (3) | 0.21 (−0.06 to 0.05) | 0.20 (−0.03 to 0.44) |
| Smoking status in 2013, n (%) | |||
| Never | 3596 (57) | Reference category | Reference category |
| Past | 1398 (22) | −0.06 (−0.11 to 0.96) | 0.12 (−0.01 to 0.25) |
| Occasional | 544 (9) | −0.10 (−0.25 to 0.05) | 0.09 (−0.98 to 0.27) |
| Daily | 781 (12) | −0.39 (−0.52 to −0.27) | 0.07 (−0.10 to 0.24) |
| Smoking status in 2018, n (%) | |||
| Never | 3594 (57) | Reference category | Reference category |
| Past | 1591 (25) | −0.01 (−0.11 to 0.08) | 0.07 (−0.02 to 0.15) |
| Occasional | 483 (8) | −0.04 (−0.19 to 0.12) | 0.04 (−0.09 to 0.18) |
| Daily | 571 (9) | −0.15 (−0.30 to −0.01) | 0.26 (0.13 to 0.38) |
| Change in smoking habit, n (%) | |||
| No | 5278 (83) | Reference category | Reference category |
| Yes, decreased | 566 (9) | −0.30 (−0.45 to −0.16) | −0.13 (−0.26 to −0.01) |
| Yes, increased | 362 (6) | 0.21 (0.03 to 0.38) | 0.23 (0.08 to 0.38) |
| Physician-diagnosed asthma in 2013, n (%) | |||
| No | 5697 (90) | Reference category | Reference category |
| Yes | 653 (10) | −0.59 (−0.72 to −0.46) | 0.89 (0.75 to 1.0) |
| BMI category in 2013, n (%) | |||
| Normal weight (<24.9 kg/m2) | 3245 (51) | Reference category | Reference category |
| Overweight (25–29.9 kg/m2) | 2212 (35) | −0.10 (−0.19 to −0.12) | 0.008 (−0.67 to 0.09) |
| Obese (>30 kg/m2) | 893 (14) | −0.19 (−0.31 to −0.067) | 0.15 (0.05 to 0.26) |
| Change in BMI (kg/m2), mean (SD) | 0.56 (2.43) | 0.050 (0.033 to 0.066) | 0.045 (0.03 to 0.06) |
| Symptom score in 2013, burden score (SD) | 1.12 (1.78) | −0.46 (−0.48 to −0.44) | Not applicable |
| Change in VGDF exposure* score (SD) | −0.15 (1.03) | 0.07 (0.03 to 0.11) | 0.068 (0.03 to 0.11) |
| VGDF exposure in 2013*†, n (%) | |||
| Never | 2705 (49) | Reference category | Reference category |
| Seldom | 1418 (26) | −0.07 (−0.17 to 0.04) | −0.01 (−0.09 to 0.09) |
| Weekly | 554 (10) | −0.07 (−0.22 to 0.08) | 0.08 (−0.05 to 0.21) |
| Daily, short | 505 (9) | 0.03 (−0.12 to 0.19) | 0.18 (0.05 to 0.32) |
| Daily, most | 292 (5) | −0.07 (−0.26 to 0.13) | 0.18 (0.10 to 0.35) |
Statistically significant findings (p<0.05) are in bold.
Missing values for smoking are not included in the models.
*Exposure to VGDF is restricted to subjects employed in the last 12 months in 2013 (n=5541).
†67 subjects did not provide a response to this question.
BMI, body mass index; VGDF, vapours, gas, dust and fumes.