Sample size was calculated taking into account a relevant ACT score difference of 3 points and a SD of 4.4 (SCHATZ M et all. Asthma Control Test: reliability, validity, and responsiveness in patients not previously followed by asthma specialists. J Allergy Clin Immunol 2006;117:549-56). In order to be able to detect this difference with α and β errors of 5% and 20% respectively, the investigators calculated 32 patients per group.