The specific aim of this study is to describe 1 year Advair dispensing rates for patients with COPD, and to measure the association between Advair adherence and healthcare utilization (e.g. emergency room visits and inpatient admissions, etc.). To compare the risk of a COPD exacerbation (moderate or severe) during a 3-month follow-up period between patients thqat are adherent versus those that are not.