Prescribing patterns of central nervous system drugs among children, adolescents and their families with/without treatment for ADHD

Abstract

This study set out to investigate possible differences in the prescribing patterns of central nervous system (CNS) medication in children and adolescents with and without treatment for ADHD in the South African private health sector, as well as family tendencies regarding methylphenidate and atomoxetine usage. A retrospective, longitudinal study was performed analysing medicine claims data from a nationally representative Pharmaceutical Benefit Management (PBM) company for the study period 1 January 2005 to 31 December 2013. During the study period, the prevalence of ADHD in children and adolescents increased from 2.11% in 2005 to 4.40% in 2013. When the ADHD prevalence in families of children with and without ADHD was analysed, there was an increase from 2005 (14.94%) to 2013 (29.09%). ADHD children and adolescents who also received prescriptions for other CNS medication received higher average prescribed daily doses (PDD) than ADHD children and adolescents who did not receive any CNS medication. The highest number of methylphenidate- (16.69%) and atomoxetine- (13.75%) containing items that exceeded the recommended daily dose was for children six years and younger. Prevalence of CNS medication usage in children and adolescents aged 18 years and younger decreased from 5.12% in 2005 to 4.48% in 2013. ADHD children and adolescents who received CNS medication increased, whereas prescribing decreased in CNS-only children and adolescents. Antidepressants were the most prevalent CNS active ingredient prescribed to ADHD children, and represented 41.51% of all CNS prescriptions. Among the antidepressants, the selective serotonin reuptake inhibitors (SSRIs) were the most frequently prescribed (20.99%). The most common prescribed CNS medication prescribed to non-ADHD children and adolescents was the pharmacological class anxiolytic agents (39.12%). Potential drug-drug interactions, including potential significant level 1, 4 and 5 drug-drug interactions, were identified in a total 1.94% (n = 4 530) of all prescriptions for methylphenidate. The highest number of potential drug-drug interactions with methylphenidate was found in prescriptions for which imipramine (51.79%) and amitriptyline (37.00%) were indicated. Of all atomoxetine prescriptions claimed during the study period, 3.89% (n = 1 038) had potential significant level 1 or 2 drug-drug interactions. Overall, escitalopram (37.67%) and citalopram (29.58%), in combination with atomoxetine, accounted for the most frequent potential drug-drug interactions. In conclusion, this study established prevalence statistics of ADHD in South African children and adolescents, as well as the prevalence of CNS medication usage among these children and adolescents. Secondly, the prevalence of ADHD in families of children and adolescents with, and without ADHD, was determined. Methylphenidate and atomoxetine prescribing patterns in children and adolescents were determined by comparing the prescribed daily dose and the recommended daily dose in the different age groups. This study also concluded the prevalence of CNS medication usage among ADHD and non-ADHD children and adolescents with specific reference to age- and gender groups and the most frequently prescribed CNS medications for both the ADHD children and adolescents and the non-ADHD children and adolescents. Lastly, potential drug-drug interactions were determined on prescriptions for methylphenidate and atomoxetine and other CNS medication.