Mixed model used: percentage of days with no rescue medication use = treatment + age + gender + baseline percentage of days with no rescue use + level of asthma control + region + center (region) + error. Center is included as a random effect nested within region.
A day with no rescue use is defined from diary data as any day where the subject does not use any puffs of rescue medication.
The total number of days with no rescue use over the 4 week treatment period is divided by the total number of evaluable days in order to derive the percentage of days with no rescue use.