Significance of Medication History at the Time of Entry into the COPDGene Study: Relationship with Exacerbation and CT Metrics.

BACKGROUND: Despite the importance of respiratory medication use in COPD, relatively little is known about which clinical phenotypes were associated with respiratory medications.
METHODS: To determine the association between respiratory medication use and exacerbations or quantitative CT metrics, we analyzed medication history from 4,484 COPD subjects enrolled in the COPDGene Study.
RESULTS: 2,941 (65.6%) subjects were receiving one or more respiratory medications; this group experienced more frequent exacerbations in the year before study entry and had increased gas trapping, emphysema, and subsegmental airway wall area, compared to the patients who were on no respiratory medication. In subgroup analysis, subjects who were on triple therapy (long-acting beta2-agonist [LABA], long-acting muscarinic antagonist [LAMA], and inhaled corticosteroids [ICS]) had the highest frequencies of exacerbations and severe exacerbations and tended to have increased quantitative measures of emphysema and gas trapping on CT compared to other five groups. After adjustment for confounding variables, the triple therapy group experienced more exacerbations and severe exacerbations compared with other five groups. In addition, the LABA+LAMA+ICS group was more likely to have emphysema and gas trapping on CT than other groups in multivariable logistic analysis. Interestingly, the total number of respiratory medications was significantly associated with not only the frequency of exacerbations but also gas trapping and airway wall thickness as assessed by CT scan in multivariable analysis.
CONCLUSIONS: These results suggest that the use of respiratory medications, especially the number of medications, may identify a more severe phenotype of COPD that is highly susceptible to COPD exacerbations.