 tiotropium and fluticasone propionate/salmeterol groups before and after matching.\ **Abbreviations:** CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; Dx, diagnosis; ED, emergency department; OCS, oral corticosteroid; Outpt, outpatient; SABA, short-acting beta-agonist.](copd-0-000f0){#f0-copd-0-000}  ![Standardized difference