Decline in FEV1 related to smoking status in individuals with severe alpha1-antitrypsin deficiency (PiZZ)

Severe alpha1-antitrypsin (AAT) deficiency predisposes to emphysema development. Highly variable rates of decline in lung function are reported in PiZZ individuals. The annual decline in forced expiratory volume in one second (FEV1; delta FEV1) was analysed in relation to smoking status in a cohort of 608 adult PiZZ individuals included in the Swedish national AAT deficiency register. Delta FEV1 was analysed in 211 never-smokers, in 351 exsmokers, and in 46 current smokers after performing at least two spirometries during a follow-up time of 1 yr or longer (median 5.5 yrs, range 1-31). The adjusted mean delta FEV1 in never-smokers was 47 mL x yr(-1) (95% confidence interval (CI) 41-53 mL x yr(-1)), 41 mL x yr(-1) (95% CI 36-48 mL x yr(-1)) in exsmokers, and 70 mL x yr(-1) (95% CI 58-82 mL x yr(-1)) in current smokers. A dose-response relationship was found between cigarette consumption and delta FEV1 in current smokers and exsmokers. In never-smokers, a greater delta FEV1 was found after 50 yrs of age than before. No sex differences were found in delta FEV1. In conclusion, among PiZZ individuals, the change in forced expiratory volume in one second is essentially the same in never-smokers and exsmokers. Smoking is associated with a dose-dependent increase in the change in forced expiratory volume in one second.