Treatment adherence and persistence in adult ADHD: Results from a twenty-four week controlled clinical trial with extended release methylphenidate

PurposeThe aim of this analysis is to describe medication adherence, and treatment persistence, in adults with attention deficit/hyperactivity disorder (ADHD) treated for 24 weeks with extended release methylphenidate (MPH-ER). Additionally, patient-, disorder- and treatment-related factors associated with adherence and persistence will be identified.MethodPost-hoc analysis of the active treatment group of a placebo-controlled, randomised, 24 week trial with MPH-ER with univariate description and multiple logistic regression models and Hosmer and Lemeshow tests.ResultsIn the sample of 241 adults with ADHD (mean age of 35.2 ± 10.1 years), 9.4% of the patients were non-adherent, taking less than 80% of the dispensed medication. Factors associated with non-adherence included age < 25 years, education level lower than secondary education, lacking family history of ADHD, lower ADHD baseline severity and lower self- and observer-rated medication efficacy. Lacking family history of ADHD, lower education level and lower self-rated medication efficacy, predicted non-adherence with a prediction accuracy of 16%. Seventeen percent of the patients discontinued early with most discontinuing within the first five weeks of the MPH-ER titration phase. Mean persistence in the discontinuing group was 63.4 ± 49.4 days. Factors associated with discontinuation included male gender, lower education level, lacking family history of ADHD and lower self- and observer-rated medication efficacy. Treatment non-response, male gender and lower education level predicted treatment discontinuation with a prediction accuracy of 22.7%.ConclusionMale adults without relatives with ADHD, with lower educational level and lower self- and observer-rated medication efficacy, who are newly treated with MPH-ER, are at increased risk of non-adherence and treatment discontinuation. Patients are at increased risk of treatment discontinuation during the medication titration phase.