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 = 0.026), shorter duration of smoking abstinence (p = 0.008), higher baseline FEV₁ (p = 0.003), higher annual exacerbation frequency (p = 0.003) and higher frequency of glucocorticoids intake (p = 0.004). Furthermore, patients with an elevated decline in TLCO showed significant impaired health-related quality of life at baseline (p = 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.

Keywords: AATD; Alpha-1-antitrypsin deficiency; COPD; Exacerbations; FEV(1); Smoking abstinence.