Outcomes for Chronic Obstructive Pulmonary Disease Moderate Exacerbators Initiating Treatment

Data from January 1, 2003 to March 31, 2009 will be available and termed as the study period. Patients with at least one moderate exacerbation defined as a physician/outpatient visit with a primary diagnosis of COPD and having an oral corticosteroid (OCS) or antibiotic prescription (ABX) within 5 days of physician/outpatient visit will be identified as the target population. The date of the first moderate exacerbation will serve as the patient's index date, and will be identified during the identification period of January 1, 2004 through February 28, 2009. Furthermore this moderate exacerbation should be the first medical claim with a primary diagnosis of COPD to ensure that only patients with moderate exacerbations will be captured. Subsequently, patients will be categorized into study cohorts based on the first maintenance drug prescription (index drug) received during the 30-day period after the index date termed as the treatment assessment period. Maintenance drugs considered include fluticasone-salmeterol 250/50 mcg (FSC) or anticholinergics (AC) including tiotropium (TIO) and ipratropium or combination ipratropium-albuterol (collectively referred to as ipratropium [IPR]). Patients not receiving any maintenance medication or those receiving maintenance medications other than those considered during the treatment assessment period will be excluded.

All outcomes will be assessed during a follow-up period that will vary in length between 1 day and 1 year for each patient. The variable follow-up period will be defined as the period that starts on the day after the treatment assessment period, and ends on the earliest of the following event dates: the end of the study period (March 31, 2009), the end of the patient's continuous eligibility in the health plan, the end of the patient's 1-year follow-up, treatment switch date (ie, a switch to any study medication different from the index drug), discontinuation date of the index drug (ie, more than a 60-day gap between the end of the days' supply of the preceding prescription and the fill date of the next consecutive prescription), or occurrence of any COPD-related exacerbation (COPD-related hospitalization, ED visit, or physician/outpatient visit with a prescription for an oral corticosteroid or antibiotic within 5 days of the visit).

A 1-year period before the index date (pre-period) will be used to provide a baseline assessment of the study cohorts. The specific dates for the pre- and follow-up periods will vary for each patient depending on their index date.

Specifically the study hypothesis for the primary outcome being tested was:

Ho: There is no difference in risk of any COPD-related exacerbation between FSC and AC cohorts Ha: There is a difference in risk of any COPD-related exacerbation between FSC and AC cohorts

Hypothesis for the key secondary outcome of COPD-related costs that was tested was:

Ho: There is no difference in COPD-related costs between FSC and AC cohorts Ha: There is a difference in COPD-related costs between FSC and AC cohorts