The objective of the study was to compare in real life clinical practice two treatment regimens: inhaled glucocorticosteroid + salmeterol and inhaled glucocorticosteroid + montelukast.

48 month pre/post retrospective repeated measures design was used to compare the level of asthma control among patients continuously treated at the Outpatient Asthma and Allergy Treatment Center, Chair of Clinical Immunology and Microbiology, Medical University of Lodz, Poland.

Inclusion Criteria:

• Clinical diagnosis of asthma according to the WHO/GINA 2006 definition by the physicians of the Centre, backed up by detailed medical history and physical examination as well as additional spirometry and bronchodilatation test or methacholine challenge where necessary
• Occurrence of an index event (intervention) defined as the first prescription for salmeterol or montelukast, establishing a 12-month pre-index and three consecutive 12-month post-index periods
• At least one inhaled glucocorticosteroid prescription in the pre-index period, and at least one salmeterol/montelukast prescription depending on the arm in every post-index period

Exclusion Criteria:

• Incomplete diagnostics

The study population consisted of 5563 patients continuously treated for bronchial asthma (28% of all patients) at the Outpatient Asthma and Allergy Treatment Center, Chair of Clinical Immunology and Microbiology, Medical University of Lodz, Poland in the period from April 1995 through June 2006.