PURPOSE OF THE STUDY.
To compare subjective and objective measurements of adherence to inhaled corticosteroids versus placebo and to determine if adherence to study medications modified treatment-related outcomes.
One hundred forty children aged 5 to 12 years who were diagnosed with mild or moderate asthma were enrolled from 3 of 8 sites from the Childhood Asthma Management Program (CAMP) study.
This was a prospective study over a 4-year study period. The study population was categorized with mild or moderate asthma based on criteria established in the CAMP trial. Subjects were randomly assigned to receive either placebo, budesonide, or nedocromil twice daily over 4 years; those in the placebo and budesonide arms were included in this ancillary adherence report from 3 centers. Adherence measures were categorized as either self-reported or objective. Self-reported adherence consisted of daily diary entries by patient or caregiver that were reviewed at follow-up visits every 4 months. Objective adherence measures included counting the doses remaining in the Turbuhaler device (ie, doses dispensed).
Objective adherence measurements were significantly lower than self-reported adherence measurements. There was poor agreement between self-reported and objective measures of adherence, with 75% of participants demonstrating <80% adherence by objective measurements, whereas only 5.8% of self-reported adherence values were <80%. Self-reported adherence overestimated objective adherence measures by 30% (93.6% vs 60.8%, P < .0001) during the 4-year study period. Adherence reporting was similar between placebo and budesonide treatment groups. Only the “high-adherence” budesonide group was associated with improved outcomes (change in forced expiratory volume in 1 second before and after bronchodilator use), a finding that may have impacted the overall CAMP study findings.
Self-reported adherence data overestimated objectively measured adherence by 30%, making self-reported medication use misleading during clinical trials.
This study adds to the evidence base that self-reporting of adherence is erroneous and may result in misleading outcome reporting in clinical trials. This study also provides information that can be useful to the practicing clinician regarding the use of objective, rather than self-reported, adherence during clinical decision-making when possible.
- Copyright © 2012 by the American Academy of Pediatrics