Exacerbations and duration of smoking abstinence are associated with the annual loss of FEV1 in individuals with PiZZ alpha-1-antitrypsin deficiency

Abstract

Background: Alpha-1-antitrypsin deficiency (AATD) is a genetic disorder that is associated with a higher risk of chronic obstructive pulmonary disease (COPD) and emphysema. The annual declines in lung function (FEV1) and transfer factor of the lung for carbon monoxide (TLCO) predict all-cause mortality. Material and methods: We investigated the longitudinal follow-up data over 11 years (mean follow-up period of 4.89 years) from the German AATD registry and analyzed the relationship between annual loss of FEV1 and TLCO and sex, age, body mass index (BMI), nicotine consumption, occupational dust exposure, St. George's Respiratory Questionnaire (SGRQ) score, baseline FEV1 or TLCO, alpha-1- antitrypsin (AAT) serum level, exacerbation frequency and the duration of smoking abstinence by multiple linear generalized estimating equations models (GEE-models). Results: We evaluated the data of 100 individuals with post-bronchodilator FEV1 measurements and from 116 individuals with TLCO measurements. The mean overall decline was 54.06 ± 164.62 ml/year in FEV1 and -0.17 ± 0.70 mmol/min/kPa/year in TLCO. Accelerated deterioration of FEV1 was associated with occupational dust exposure (p ¼ 0.026), shorter duration of smoking abstinence (p ¼ 0.008), higher baseline FEV1 (p ¼ 0.003), higher annual exacerbation frequency (p ¼ 0.003) and higher frequency of glucocorticoids intake (p ¼ 0.004). Furthermore, patients with an elevated decline in TLCO showed significant impaired health-related quality of life at baseline (p ¼ 0.039) and lower AAT serum levels (p < 0.001) in multivariate analysis. Conclusions: Annual decline in FEV1 is related to the exacerbation rate, occupational dust exposure and the duration of smoking abstinence.