Sublingual immunotherapy in youngsters: adherence in a randomized clinical trial

Background Adherence is essential for effective treatment. Although several trials on the efficacy of sublingual immunotherapy (SLIT) in youngsters have been published, few contain data on medication intake. Objective We aimed to quantify adherence both to study protocol and medication intake as well as to identify factors that may influence adherence to SLIT in youngsters with rhinoconjunctivitis. Methods Two hundred and four youngsters (6-18 years) with hayfever participated in a randomized controlled trial and used grass pollen extract or placebo for 2 years. The primary Outcome of the trial was the mean daily total rhinoconjunctivitis symptom score in the second grass pollen season. Participants having completed the follow-up were considered adherent to the study protocol. Adherence to medication intake was assessed by weighing the study medication. Participants who completed the follow-up and used >= 80% of the prescribed medication were considered adherent to medication intake. Patient-, disease- and treatment-related factors were analysed. Results One hundred and fifty-four youngsters completed the study. The main reason for discontinuation was the inability to take medication according to schedule. Drop-outs were older, had more difficulty following the medication instructions and their overall evaluation of the treatment effect was lower. The number and reasons for drop-out did not differ between treatment groups. In total, 77% of the participants was adherent to medication intake. Self-reported adherence was 99%. Non-adherent participants experienced more severe symptoms before the trial. Symptom scores did not differ between adherent and non-adherent participants. In adherent as well as non-adherent participants, no difference was found between verum and placebo group with respect to symptom scores. Conclusion Adherence to both study protocol and medication intake was good. Drop-out was affected by age, evaluation of the treatment effect and medication instructions. Nonadherence to medication intake was influenced by the severity of the disease before the trial. The ineffectiveness of SLIT could not be explained by non-adherence