The changing prevalence of attention-deficit/hyperactivity disorder and methylphenidate prescriptions: a study of data from a random sample of insurees of the AOK Health Insurance Company in the German State of Hesse, 2000-2007.

Background: The goal of this study is to assess changes in the prevalence of attention-deficit/hyperactivity disorder (ADHD) and methylphenidate prescriptions over the period 2000 to 2007 on the basis of data from a German statutory health insurance carrier.
Methods: In a cross-sectional study, we analyzed data from a random sample of insurees of the AOK health insurance company in the German state of Hesse for the years 2000 to 2007. Per calender year, 50,000 to 63,000 children and adolescents were retrospectively observed with respect to the documentation of ADHD diagnosis (ICD-10 diagnosis F90) and the prescribing of methylphenidate (ATC: N06BA04).
Results: In 2007, the overall prevalence of ADHD in all age groups (0-18 years) was 2.21% (95% CI: 2.09-2.34). This figure was 45% greater than the corresponding figure for the year 2000. The prevalence increased by a larger amount among girls aged 6 to 18 years than among boys in the same age group (+69% vs. +53%). In 2007, 1.06% (95% CI: 0.98-1.16) of the children/adolescents received at least one prescription for methylphenidate; this was a 96% increase over the prescription rate for 2000. A comparison of the two years 2000 and 2007 reveals a clear prevalence shift towards the older age groups, as well as an 82% increase in the average number of daily doses per recipient. Outpatient departments of child and adolescent psychiatry initiated more treatments in 2007 than in 2000.
Conclusion: The 1% prevalence of methylphenidate use among children and adolescents that was found in this study is the same as that reported in other European countries, such as Switzerland, the Netherlands, and Norway. A drawback of our study is its limitation to a single insurance carrier in a single region. Nonetheless, data of this type are useful for monitoring. The findings suggest further issues worth studying, e.g., off-label use or the indications for treatment in older age groups.