Asthma drug adherence in a long term clinical trial

Aim-To measure drug adherence in children with mild asthma receiving long t erm prophylactic treatment. Methods-Double blind randomised placebo controlled trial. Patients received inhaled budesonide 100 mu g or 200 mu g daily, or placebo for 27 months. A ll participants were asked to inhale medication or placebo from two differe nt Turbuhalers (morning and evening) during the study. A total of 122 child ren (80 boys, 42 girls) aged 7-16 years with mild asthma (mean FEV1 103.7% of predicted) were included in the trial. Drug adherence was assessed by co unting the number of remaining doses in the inhaler when study medication w as returned at six month intervals. Results-A statistically significant and continuing decrease in measured dru g adherence was found from three to nine months and then to 27 months, reac hing mean values of 40.6% and 46.9% for inhaled morning and evening medicat ion respectively. Drug adherence declined more rapidly in the placebo group (compared to active treatment); this difference became significant after t wo years of treatment. Children aged 9 years or less had better drug adhere nce during the entire study period, but the difference was only significant for the first three months of the study. Measured drug adherence was signi ficantly higher for evening medication compared to morning medication for a ll study intervals after nine months. Conclusion-Measured drug adherence diminishes significantly when treating c hildren with mild asthma in a long term trial. This emphasises the importan ce of monitoring compliance in clinical trials.