Bronchodilation and Smoking Interaction in COPD: A Cohort Pilot Study to Assess Cardiovascular Risk

BACKGROUND: Smoking and bronchodilator treatment are both extensively studied as key elements in patients with chronic obstructive pulmonary disease. However, little is known about whether or not these elements interact in terms of developing cardiovascular diseases in patients with COPD. OBJECTIVES: To explore to what extent the risk of developing ischemic cardiovascular disease in COPD patients is mediated by smoking status, use of bronchodilators and--specifically--their interaction. METHODS: We performed an observational pilot study on a relatively healthy Dutch COPD cohort from a primary care diagnostic center database with full information on spirometry tests, smoking status, bronchodilator use and other prescribed medication. We defined first ischemic cardiovascular events as primary outcome, measured by first prescription of antiplatelet drugs and/or nitrates. Unadjusted analyses by Kaplan-Meier were followed by adjusted Cox' proportional hazards. RESULTS: 845 COPD patients, totaling 2,169 observation years, were included in the analyses. We observed an increased risk for nonfatal ischemic cardiovascular events by smoking (adjusted HR=3.58, p=0.001) and a protective effect of bronchodilators (adjusted HR=0.43, p=0.01). Although the protective effect of bronchodilators appears to be substantially minimized in patients that persist in smoking, we could not statistically confirm a hazardous interaction between bronchodilators and smoking (HR 2.50, p=0.21). CONCLUSION: Our study reveals bronchodilators may protect from ischemic cardiovascular events in a relatively 'healthy' COPD population. We did not confirm a hazardous interaction between bronchodilators and smoking, although we observed current smokers benefit substantially less from the protective effect of bronchodilators.