Overuse of methylphenidate: an analysis of Swedish pharmacy dispensing data

To identify overuse of methylphenidate and to investigate patterns of overuse in relation to sociodemographic and clinical characteristics.

Swedish national, pharmacy dispensing data were analyzed for all 56,922 individuals aged 6-79 years, who filled a methylphenidate prescription between 2010 and 2011. Overuse was defined as having above 150% days covered by the dispensed amount during 365 days from the first prescription fill, assuming use at the maximum recommended daily dose.

In total, 4,304 individuals (7.6% of the methylphenidate users) were categorized as overusers. The risk of overuse increased with age (OR for 46-65 years vs 6-12 years 17.5, 95% CI 14.3-21.3), and was higher in men (OR 1.4, 95% CI 1.3-1.5) and individuals with low income (OR 1.1, 95% CI 1.0-1.2), as well as in individuals with an attention deficit hyperactivity disorder (ADHD) diagnosis (OR 1.4, 95% CI 1.3-1.6), health care visits (OR 1.3, 95% CI 1.2-1.4), previous ADHD medication use (OR 2.6, 95% CI 2.4-2.8), and previous diagnosis of mental and behavioral disorders due to psychoactive substance use (OR 2.1 95% CI 2.0-2.3).

Among individuals using methylphenidate in Sweden, 7.6% receive amounts that are larger than what they should have a medical need for, assuming that they were using the maximum recommended daily dose 365 days per year. Notably, the prevalence of overuse was associated with previous diagnosis of alcohol and drug misuse. The prevalence was also positively associated with higher age and previous use of ADHD medication. These findings may point toward a link between exposure time and overuse. However, future studies with long-term data are needed to investigate this.