gms | German Medical Science

Background: Methylphenidate is mainly prescribed in children and adolescents with attention deficit / hyperactivity disorder (ADHD). The use of methylphenidate is contraindicated in the presence of certain psychiatric, cerebro- and cardiovascular conditions. In this study, we estimated the frequency of specific comorbid conditions in methylphenidate users and nonusers.

Methods: We used health care data for the years 2004-2006 from the German Pharmacoepidemiological Research Database (GePaRD), including more than 14 million insurees from all regions of Germany. Methylphenidate treatment was considered prevalent if there was at least one prescription of methylphenidate in the specific year and incident, if no methylphenidate prescription was filled twelve months preceding the first prescription. The presence of preselected comorbid conditions in incident users of methylphenidate was compared to a control group (nonusers) defined as children who had no prescription of methylphenidate or atomoxetine and no diagnosis of ADHD (ICD-10 code F90) during the study period. In users, the prevalence of comorbidities was assessed in the four quarters preceding the first prescription, whereas in nonusers it was assessed in the earliest four quarters of continuous insurance time starting at 01.01.2004 or the begin of insurance. Differences in the presence of comorbid diagnoses between users and nonusers were tested by applying logistic regression adjusting for age as a categorical variable.

Results: In 2005, 1.5% of all children and adolescents aged 3 to 17 years (2.3% of males and 0.6% of females) received methylphenidate (1.7% in 2006). The proportion of children with a record of a psychiatric comorbidity in all nine categories of diagnoses (F10-F19, F20-F29, F30-F39, F40-F49, F50-F59, F60-F69, F70-F79, F80-89 and F91-F98) was higher in incident methylphenidate users compared to nonusers. About half of all incident users had a record of behavioural or emotional disorders (F91-F98; 56% in males and 54% in females) and also about one half a record of disorders of psychological development (F80-F89, 52% in males and 48% in females). Cerebro- and cardiovascular comorbidities were rare in general. Still, among new users, 2% of males and females had a diagnosis of a pre-existing cardiovascular disorder but only 1.2% of nonusers.

Conclusion: A high proportion of children who were started on methylphenidate had a record of a psychiatric comorbidity. Cerebro- and cardiovascular conditions were rare in that age range. Since some of the studied diagnoses, depending on severity, were recently listed as contraindications for methylphenidate, the results could have practical implications for future methylphenidate prescribing behaviour.