Adjusted differences* in annual change in lung function during follow-up in association with outdoor PM10 and occupational VGDF exposures during follow-up in PiMZ and PiMM carriers by smoking status
| ΔFEV1 (mL) | ΔFVC (mL) | ΔFEV1/FVC (%) | ΔFEF25–75% (mL/s) | |||||
|---|---|---|---|---|---|---|---|---|
| Ever smokers | Never smokers | Ever smokers | Never smokers | Ever smokers | Never smokers | Ever smokers | Never smokers | |
| β† (95% CI) | β†(95% CI) | β†(95% CI) | β† (95% CI) | β† (95% CI) | β†(95% CI) | β† (95% CI) | β† (95% CI) | |
| ▵PM10 (per 10 μg/m3 in 10 years) | ||||||||
| PiMZ (n=48, n=49)‡ | −6 (−21 to 10) | −8 (−29 to 12) | 1 (−20 to 21) | −9 (−36 to 18) | −0.2 (−0.5 to 0.0) | −0.0 (−0.4 to 0.3) | −28 (−63 to 6) | −9 (−55 to 37) |
| PiMM (n=2055, n=1587)‡ | −2 (−7 to 2) | −5 (−9 to −0) | 1 (−5 to 7) | −1 (−7 to 5) | −0.0 (−0.1 to 0.0) | −0.0 (−0.1 to 0.0) | −9 (−17 to 1) | −16 (−26 to −5) |
| High-level VGDF exposure§ | ||||||||
| PiMZ (n=48, n=49) | −4 (−27 to 18) | −18 (−57 to 20) | 23 (−5 to 53) | −35 (−86 to 15) | −0.4 (−0.8 to −0.0) | 0.1 (−0.5 to 0.8) | −109 (−159 to −59) | 9 (−78 to 95) |
| PiMM (n=2055, n=1587) | 4 (−0 to 8) | −2 (−7 to 2) | 1 (−5 to 6) | −6 (−12 to −0) | 0.1 (−0.0 to 0.1) | 0.1 (−0.0 to 0.1) | 8 (−0 to 17) | 4 (−6 to 13) |
*Annual change in lung function was modelled in linear mixed regression with random intercept for area consisting of the following baseline covariates: age, age squared, sex, foreign status, height, body mass index, early respiratory infection, parental asthma, high-level education, cumulative VGDF exposure, and outdoor PM10; additional covariates included smoking status through follow-up, cumulative pack-years through follow-up, daily environmental tobacco smoke exposure at follow-up, difference in body mass index over follow-up period, seasonality, ▵PM10, high-level VGDF exposure during follow-up, SERPINA1 genotype (PiMZ, PiMM as reference), and two-way interaction terms between environmental tobacco smoke exposure at follow-up and SERPINA1 genotype, smoking status through follow-up and SERPINA1 genotype, ▵PM10 and SERPINA1 genotype, ▵PM10 and smoking status through follow-up, high-level VGDF exposure during follow-up and SERPINA1 genotype, and high-level VGDF exposure during follow-up and smoking status through follow-up; we estimated the effect of ▵PM10 and high-level VGDF exposure during follow-up on annual change in lung function by SERPINA1 genotype and smoking status by adding interaction terms in the model.
†Negative signs indicate acceleration of decline in the lung function parameter with higher levels of exposure to the inhalants.
‡Number of subjects in ever smoker and never smoker subgroups, respectively.
§A statistically significant three-way interaction was observed between SERPINA1 genotype, high-level VGDF exposure and smoking status on ▵FEF25–75% (p=0.01); in ever smokers, statistically significant two-way interactions were observed between SERPINA1 genotype and high-level VGDF exposure on ▵FEF25–75% (p<0.0001) and on ▵FEV1/FVC (p=0.02).
FVC, forced vital capacity; FEF, forced expiratory flow; FEV, forced expiratory volume; VGDF, vapours, dusts, gases and fumes.