This patient presented with symptomatic airflow obstruction and emphysema in the context of underlying A1AT deficiency. Importantly, the patient manifested accelerated lung function decline during the period of highest occupational concrete dust exposure and attenuated decline once such exposure ceased. Using a NIOSH-recommended analytic approach, the decline in FEV
1 values from workplace surveillance spirometry was found to be steeper than the normal age-associated slope, but attenuated after occupational exposure discontinued. This divergence in trajectory is also consistent with the separate break-point statistical analysis we performed. Moreover, the patient's post-exposure decline in FEV
1 (-46 ml/year) is slightly less than the annual decline that has been reported in untreated A1AT patients (-60 ± 7 ml/year) [
8]. Of note, we do not have systematic data on symptoms over time to correlate with the lung function data; for example, repeated measures using the Borg Dyspnea scale or the Medical Research Council assessment for shortness of breath.
Although cigarette smoking is a well-established co-factor in airflow obstruction and emphysema among people with A1AT deficiency, occupation has also been implicated as a risk factor for worse disease status in several epidemiological studies of A1AT-deficient people with or without work-related exposures. The largest study of this question found a lower FEV
1 value in adults ages 50 years and above with PiZZ phenotype A1AT who self-reported occupational exposures to gas, fumes or dust for at least three months [
3]. Other cross-sectional observational studies support this association [
4,
5]. A recent study also reported accelerated decline in lung function among 11 rescue workers with mild to moderate A1AT deficiency (no PiZZ phenotypes) exposed to dust after the World Trade Center collapse [
9].
Studies of uncontrolled dry concrete grinding operations have documented very high levels of both respirable suspended particulates and silica dust [
10]. In non-A1AT-deficient populations, construction work involving inorganic dust exposures (which subsumes concrete finishing) is associated with increased COPD mortality risk [
11], and occupational silica exposure (as noted, an important constituent of concrete dust) is linked to chronic airflow obstruction [
12]. The specific pattern of exposure and response in our patient, together with the broader epidemiological evidence [
1,
2,
11,
12], is consistent with a relationship between the patient's dust exposure and his COPD, with the acknowledgment that A1AT deficiency was a key mediating factor. Moreover, our report is unique in describing longitudinal exposure history coupled with measured lung function data supporting this potential effect-moderating relationship.
People with PiZZ phenotype A1AT disease should be assessed for occupational exposures and closely monitored for work-accelerated progression of lung function decline over and above the decline associated with this disease absent such exposure. More generally, this case not only points to the biological plausibility of occupationally associated COPD but also underscores that work-associated pulmonary disease can be multi-factorial.
1 Patricia J Quinlan,2 and Paul D Blanc3
