Clinical and inflammatory features of exacerbations of occupational chronic obstructive pulmonary disease

Background: Exacerbations of chronic obstructive pulmonary disease (COPD) are heterogeneous and different phenotypes were established. Less is known about exacerbations phenotypes in occupational COPD. Objective: To evaluate exacerbations phenotypes in COPD related to different occupational factors. Methods: Data on COPD exacerbations were collected during a 5-year period from 167 COPD subjects of whom 42 exposed to aromatic hydrocarbons 55 to dust and 70 tobacco smokers. Evaluation included hospitalizations, symptoms, lung function, induced sputum cytology. Pathogens in sputum were assessed by PCR and standard routine culture. Logistic regression and ANCOVA were used to explore the relationships. Results: COPD due to chemicals was associated negatively with all exacerbations OR, 0.2; 95% CI, 0.1-0.5 but positively with exacerbations requiring hospitalizations OR, 3.8; 95% CI, 1.7-8.4. Most of exacerbations in this group were eosinophilic (55%) or paucigranulocytic (31%) with greater FEV1 decline (151±10.2ml) and increase in mMRC score (1±0.5). COPD due to dust was associated negatively with exacerbations requiring hospitalizations OR, 0.3; 95% CI, 0.1-0.8. Most of exacerbations in COPD due to dust were paucigranulocytic (49%) or eosinophilic (31%) with less FEV1 decline (124±14.3 ml). Percentage of exacerbations caused by infection was 58% in COPD due to chemicals 71% in COPD due to dust and 85% in COPD due to tobacco smoke. Haemophilus influenza was more common for COPD due to tobacco smoke and Streptococcus pneumoniae for occupational COPD. Conclusions: Exacerbations of occupational COPD due to chemicals and due to dust have the potential of being distinct phenotypes.