157 An Analysis of Patient Adherence to Treatment During a 1-Year, Open-label Study of OROS® Methylphenidate in Children With ADHD 1 Stephen V. Faraone 2 SUNY Upstate Medical University Joseph Biederman 3 Massachusetts General Hospital Brenda Zimmerman 4 McNeil Consumer & Specialty Phamaceuticals Objective: Treatment adherence is an important aspect of ADHD symptom management, but there are many factors that may influence adherence. Method: This analysis assessed adherence to OROS methylphenidate during a 1-year, open-label study in children. Adherence was defined as the number of days medication was taken divided by the number of days in the study and determined to be high if ≥75%. Possible clinical and demographic factors associated with adherence, including use of planned medication breaks, were assessed. Results: Mean adherence was 86.4%. It was 91.6% for the subgroup of patients who reported not taking planned medication breaks (n = 252) and 77.7% for the subgroup taking planned medica- tion breaks (n = 155). Overall, 75% of patients showed high adherence. Older age, low starting dose, minority ethnic sta- tus, and fewer ADHD symptoms were associated with low adherence. Conclusion: Various factors were found to be associated with low adherence, and the results of this analysis provide guidance to physicians seeking to identify those patients with ADHD most likely not be adherent to stimulant therapy (J. of Att. Dis. 2007; 11(2) 157-166) Keywords: methylphenidate; attention deficit/hyperactivity disorder; children; treatment Introduction For several decades, stimulant therapy has been used to control the core symptoms of attention-deficit/hyper- activity disorder (ADHD) (American Academy of Pediatrics, 2001; Greenhill et al., 2002). Because the efficacy of stimulant medications has been demonstrated in many studies in children (Brown et al., 2005; MTA Cooperative Group, 1999; Pelham et al., 1999), and more recently in adolescents and adults (Biederman, Mick, et al., 2006; Spencer et al., 1995, 2001; Wilens et al., 2006), their use is recommended in various guide- lines for the management of ADHD (American Academy of Pediatrics, 2001; Greenhill et al., 2002). A study by Charach and colleagues was conducted to evaluate the impact of adherence to stimulant therapy on effectiveness and adverse effects during a 5-year period in children with ADHD (Charach, Ickowicz, & Schachar, 2004). Adherence was defined as taking medication for 5 or more days per week, with the exception of planned medica- tion breaks during school holidays. At the end of the study, children who were adherent to therapy showed greater teacher-reported symptom improvement than children who were nonadherent to stimulant therapy and patients who were no longer prescribed stimulant medication ( p = .04) (Charach et al., 2004). Because the beneficial effects of stimulant therapy are only apparent when therapy is ongo- ing, efficacy day-to-day depends on patient adherence. However, patient adherence is sometimes poor (Swanson, 2003; Thiruchelvam, Charach, & Schachar, 2001). The short-acting stimulant formulations, such as immediate-release methylphenidate (IR MPH) and immediate-release mixed amphetamine salts, require multiple daily doses for adequate symptom control. The Journal of Attention Disorders Volume 11 Number 2 September 2007 157-166 © 2007 Sage Publications 10.1177/1087054706295663 http://jad.sagepub.com hosted at http://online.sagepub.com