Table 3

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 smokersNever smokersEver smokersNever smokersEver smokersNever smokersEver smokersNever 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.