Decline in FEV1 and hospitalized exacerbations in individuals with severe alpha-1 antitrypsin deficiency

Background and aim: The value of the forced expiratory volume in one second (FEV1) is useful in the diagnosis and prognosis of chronic obstructive pulmonary disease (COPD). Previous studies on lung function in individuals with severe alpha-1 antitrypsin deficiency (AATD) have shown a variable annual decline in FEV1 (∆FEV1). The aim of this study was to analyze ∆FEV1 and to identify risk factors for ∆FEV1 in individuals with severe AATD.
Material and methods: Data on smoking habits, symptoms, results of lung function tests and exacerbations were obtained from the Swedish AATD Register and the Swedish National Patient Register (SNPR). The ∆FEV1 was analyzed by random-effects modeling and adjusted for age and FEV1 at baseline.
Results: One hundred and four (9%) current smokers, 539 (48%) ex-smokers and 489 (43%) never-smokers were included in the study and followed-up from 1991 to 2016. A total of 584 (52%) individuals with severe AATD had COPD at inclusion. The median (IQR) annual severe exacerbation rate was 0.66 (1.4). The adjusted mean ∆FEV1 was significantly higher in the current smokers compared with the ex-smokers and never-smokers (70 [95% CI 56–83] vs 42 [95% CI 36–48] and 32 [95% CI 25–38) mL·yr−1,], in the middle–aged individuals compared with the young individuals (48 [95% CI 41–55] vs 32 [95% CI 18–45] mL·yr−1,), in the individuals with respiratory symptoms at inclusion compared with the asymptomatic individuals (46 [95% CI 40–52] vs 30 [95% CI 22–38]mL·yr−1,), and in the individuals with frequent exacerbations compared with those with infrequent exacerbations (57 [95% CI 47–68] vs 27 [95% CI 17–37] mL·yr−1,).
Conclusion: Active smoking, age, respiratory symptoms at baseline and repeated severe exacerbations of COPD are factors associated with an accelerated decline of lung function in individuals with severe AATD.