Electronic monitoring reveals highly variable adherence patterns in patients prescribed ivacaftor ★

BackgroundPrevious studies of CF treatments have shown suboptimal adherence, though little has been reported regarding adherence patterns to ivacaftor. Electronic monitoring (EM) of adherence is considered a gold standard of measurement.MethodsAdherence rates by EM were prospectively obtained and patterns over time were analyzed. EM-derived adherence rates were compared to pharmacy refill history and self-report.Results12 subjects (age 6–48 years; CFTR-G551D mutation) previously prescribed ivacaftor were monitored for a mean of 118 days. Overall adherence by EM was 61%(SD = 28%) and decreased over time. Median duration between doses was 16.9 hours (IQR 13.9–24.1 hours) and increased over time. There was no correlation between EM-derived adherence and either refill history (84%, r = 0.26, p = 0.42) or self-report (100%, r = 0.40, p = 0.22).ConclusionsDespite the promising nature of ivacaftor, our data suggest adherence rates are suboptimal and comparable to other prescribed CF therapies, and more commonly used assessments of adherence may be unreliable.