Question 4

Could you describe the study design?

This is the first clinical trial that stratified patients according to severity of illness. Several criteria have been identified that are associated with poor clinical outcomes. These include a history of frequent exacerbations, poor underlying lung function, concomitant heart disease, chronic use of oral corticosteroids and use of home oxygen (8). Patients in this trial were stratified by the presence or absence of these risk factors. Patients not demonstrating any of these risk factors were considered as having uncomplicated bronchitis and were randomized in a blinded fashion to receive either oral levofloxacin 750 mg for 3 days or oral azithromycin 500 mg on day 1 followed by 250 mg daily for 4 days. In contrast, patients exhibiting any of the risk factors were deemed as having complicated bronchitis and then randomized to receive oral levofloxacin 750 mg daily for 5 days or oral amoxicillin 875 mg/clavulanate 125 mg twice daily for 10 days. The large size of the amoxicillin/clavulanate tablets precluded over-encapsulation so this portion of the study was single-blinded.