Abstract
BACKGROUND: Selective beta-adrenergic agonists for use in asthma are: short acting (2-6 hours) and long acting (>12 hours). There has been little controversy about using short acting beta-agonists intermittently, but long acting beta-agonists are used regularly, and their regular use has been controversial. OBJECTIVES: To determine the benefit or detriment of treatment with regular short- or long acting inhaled beta-agonists in chronic asthma. SEARCH STRATEGY: A search was carried out using the Cochrane Airways Group register. Bibliographies of identified RCTs were searched for additional relevant RCTs. Authors of identified RCTs were contacted for other published and unpublished studies. SELECTION CRITERIA: All randomised studies of at least two weeks duration, comparing a long acting inhaled beta-agonist given twice daily with any short acting inhaled beta-agonist of equivalent bronchodilator effectiveness given regularly in chronic asthma. DATA COLLECTION AND ANALYSIS: Two reviewers performed data extraction and study quality assessment independently. Authors of studies were contacted for missing data. MAIN RESULTS: 31 studies met the inclusion criteria, 24 of parallel group and 7 cross over design. Salmeterol xinafoate was used as long acting agent in 22 studies and formoterol fumarate in 9. Salbutamol was the short acting agent used in 27 studies and terbutaline in 5. The treatment period was over 2 weeks in 29 studies, and at least 12 weeks in 20. 25 studies permitted a variety of co-intervention treatments, usually inhaled corticosteroid or cromones. One study did not permit inhaled corticosteroid. Long acting beta-agonists were significantly better than short acting for a variety of lung function measurements including morning PEF (Weighted Mean Difference (WMD) 33 l/min 95% CI 25, 42) or evening PEF (WMD 26 l/min 95% CI 18, 33); and had significantly lower scores for day and night time asthma symptom scores and percentage of days and nights without symptoms. They were also associated with a significantly lower use of rescue medication both during the day and night. Risk of exacerbations was not different between the two types of agent, but most studies were of short duration which limits the power to test for such differences. REVIEWER'S CONCLUSIONS: Long acting inhaled beta-agonists have advantages across a wide range of physiological and clinical outcomes for regular treatment.