MONO: Symbicort® Single Inhaler Therapy and Conventional Best Standard Treatment for the Treatment of Persistent Asthma in Adolescents and Adults

Inclusion Criteria: * Diagnosis of asthma \>= 3 months * Prescribed daily use of glucocorticosteroids for at least 3 months prior to Visit 1 Exclusion Criteria: * Smoking history \> 10 pack-years * Asthma exacerbation requiring change in asthma treatment during the last 14 days prior to inclusion * Any significant disease or disorder that may jeopardize the safety of the patient. Additional inclusion and exclusion criteria will be evaluated by the investigator.