The goals of control status of asthma have been changed with the improvement of its management as a chronic disease; many steps should be taken to achieve asthma control as defined by the GINA/NIH guidelines. There are good results with single variables, but overall asthma control should be addressed in different ways. Most traditional clinical studies provide an incomplete assessment of disease control, despite good clinical practice. The association of inhaled corticosteroid (IC) and long-action beta 2 agonist (LABA) has already showed their efficacy to reduce asthma symptoms, exacerbations and cost for moderate and severe asthma patients as well as the improvement in their quality of life. On the other hand, even with the use of first line maintenance medication, as recommended by guidelines, some asthmatic patients fail in obtaining a total control of the disease. This lack of efficacy, led us to hypothesize, that these patients who fail in response, would present chronic and fixed airway obstruction as a consequence of persistent inflammation and airway remodeling. This study has the purpose of looking for an adequate composite measure to provide an indicator of overall asthma status more accurately and meaningfully as reflect of treatment effectiveness and disease control. For this, we will test by a randomized control trial if an additional oral corticosteroid treatment could modify spirometric and plethysmography values, nasal and low airway cytology and HRCT (to evaluate small airway) in regularly treated stable asthma patients who have a positive bronchodilator response.

To evaluate the achievement of asthma control status in asthmatic patients, regularly treated with IC + LABA to answer the following questions:

i. Is it possible to improve the pulmonary function (spirometry and plethysmography) of stable asthma patients, regularly treated with IC + LABA, who have a positive bronchodilator response, with the introduction of oral steroid?

ii. What is the relationship among nasal, induced sputum and blood cytology, as a tool to observe inflammatory airway expression, in controlled and total controlled asthma patients? What will be these values response if oral steroids have been introduced?

iii. What is the correlation between pulmonary volumes and airways inflammation to evaluate severity and control status in asthmatic patients, using plethysmography and HRCT? What will be these values response if oral steroids have been introduced?

Inclusion criteria:

• A documented clinical asthma history at least for a period of six months
• Regular treatment (IC + LABA) at least for a period of three months
• Controlled symptoms score defined by GINA 2002 criteria (daytime symptoms < 2 days a week and no night time symptoms in the last 15 days) or complete absence of chronic symptoms
• None or minimal exacerbations without emergency visits
• Absent or a minimal usage bronchodilator rescue, side effects of medication and limitation to exercises
• Documented airway reversibility of 200 ml and 7% based on predicted values of VEF1

Exclusion Criteria:

• Having a smoking history of 5 pack/years or more; having other known chronic pulmonary diseases; having side effect to oral corticosteroid
• Having an upper or lower respiratory tract infection within 4 weeks of visit 0
• Unable to do the tests involved in the study.