There is no clinically significant difference between regular or as-required short-acting beta2-agonists in terms of lung function, use of reliever medication, exacerbation rates, or quality of life:
- One systematic review (search date 2002, 22 crossover randomized controlled trials [RCTs] and eight parallel-group RCTs) examined regular versus as-required use of short-acting beta2-agonists in asthma control. Most studies did not allow concomitant use of inhaled corticosteroids, and only data from the crossover studies were suitable for pooling. The review found no difference in morning peak flow rates, but regular use improved evening peak flow rates, reduced diurnal variation, and reduced the need for reliever medication. However, the clinical relevance of these results is uncertain, because exacerbation rates, and quality-of-life scores did not differ and one RCT (n = 117) showed better symptom control over 24 hours with as-required use than with regular use. In some studies, regular use was associated with deterioration of airway responsiveness after stopping medication, increased allergen-induced bronchoconstriction, and tremor [Rodolfo et al, 2005].