Less discontinuation of ADHD drug use since the availability of long-acting ADHD medication in children, adolescents and adults under the age of 45 years in the Netherlands

Treatment options for ADHD in the Netherlands have increased with the introduction of the extended-release formulations of methylphenidate (MPH ER, Concerta(®)) in 2003 and atomoxetine (ATX, Strattera(®)) in 2005, but data on the effect on drug usage patterns are scarce. The objective of the present study was to describe changes in the patterns of ADHD medication use and determinants thereof among children, adolescents and adults (<45 years) starting ADHD medication since the introduction of MPH ER and ATX. Data were obtained from Dutch community pharmacies as collected by the Foundation for Pharmaceutical Statistics, covering 97% of all dispenses for prescription medicines to outpatients in the Netherlands. Usage patterns (continuation, discontinuation, switching and addition) of ADHD drugs were evaluated at 3, 6 and 12 months after initiation for three separate time cohorts (patients starting ADHD medication in Jan-Dec 2002, Jan 2003-June 2004, respectively July 2004-Dec 2005). It was found that between 2002 and 2006, most ADHD drug users were initiated on methylphenidate IR. Discontinuation of any ADHD drug treatment decreased over time partly in favour of switching and addition. Discontinuation at 3 months decreased from around 33% to around 25%, at 6 months from less than 50% to almost 35%, and at 12 months from just fewer than 60% to less than 45%. Discontinuation was higher among females and in adults >18 years. After the introduction of MPH ER and ATX (time cohort III), 16.5% of the incident ADHD drug users switched their medication and almost 9% added an ADHD drug to the prior ADHD drug. In conclusion, discontinuation of incident ADHD drug use is high after 3, 6 and 12 months. During the study period, the incidence of discontinuation decreased because of the availability of extended-release methylphenidate and atomoxetine.