Data for managed-care enrollees age 40 and older with a diagnosis of COPD and an index event of at least one pharmacy claim for TIO during the study period (January 1, 2003 through April 30, 2008) were identified. Subjects were required to have ≥1 exacerbation in the pre-index period (defined as a COPD-related emergency room visit or hospitalization), ≥1 prescription claim for ipratropium or ipratropium/albuterol combination in the pre-index period, ≥2 prescriptions for TIO (including the index prescription) during the post-index period, no prescription for FSC during the pre-index period, and no exacerbation or hospital/emergency room visit within 30 days after the index date. ICD-9-CM code 490.xx, bronchitis not specified as chronic or acute, was included in an attempt to enhance the validity of the analysis by capturing patients with chronic bronchitis whose condition was coded incorrectly.