Outcomes Associated With Early or Delayed Maintenance Treatment Post-Chronic Obstructive Pulmonary Disease Exacerbation

Study period for this analysis will range from January 2003 through June 2009. Patients with at least one COPD exacerbation will be selected as the initial population. Three types of COPD exacerbations will be identified: 1) hospitalization with a primary discharge diagnosis code for COPD, 2) an emergency department (ED) visit with a primary diagnosis code for COPD, 3) physician visit with a dispensing of oral corticosteroid (OCS) or antibiotic (ABX) within 5 days of the visit. Only the first two will be selected as index exacerbations, which is defined as the first chronologically occurring exacerbation for a patient. For hospitalization exacerbations the discharge date of the hospitalization will be the index date and for ED exacerbations the date of the visit will be the index date. The pre-index period will be defined as the 1-year period before index date and the post-index period will be defined as 1-year period after index date. The enrollment period will thus range from January 1, 2004 through June 30, 2008. The post-index period will be used to identify the date of receipt of prescription for first COPD maintenance medication. This date of receipt will be used to compute the time to start maintenance treatment. Maintenance treatment refers to the use of controller medications. Specifically the study hypothesis for the primary outcome being tested was: Ho: There is no difference in risk of COPD-related hospitalization/ED visit between early and delayed cohorts Ha: There is a difference in risk of COPD-related hospitalization/ED visit between early and delayed 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 early and delayed cohorts Ha: There is a difference in COPD-related costs between early and delayed cohorts