Japan's methylphenidate registry slowed prescribing for under-20s far more than for adults
- In December 2019 Japan introduced a nationwide registration system for extended-release methylphenidate: prescribing physicians and dispensing pharmacies must be registered. Prescribing was traced in national claims open data for 2016–2018 and 2020–2022.
- Prescriptions kept rising after the change, but the annual growth slowed from 27% (IRR = 1.27) to 9% (IRR = 1.09), with an immediate drop of 7% (IRR = 0.93, 95% CI 0.89–0.96).
- In people under 20 the immediate decline was 47% (IRR = 0.53, 95% CI 0.42–0.68) and the post-policy slope was IRR = 1.02, close to flat; in adults aged 20 and over the drop was 19% (IRR = 0.81, 95% CI 0.79–0.84) and growth continued, the slope moving from 1.51 to 1.15.
- Regional prescribing correlated only weakly with the density of board-certified pediatricians, from r = 0.326 in 2016 to r = 0.235 in 2022.
Since December 2019, extended-release methylphenidate in Japan has moved through a national registry: the prescribing physician and the dispensing pharmacy must be registered, and the authors note that patients are registered as well. A pharmacy team at Zikei Hospital in Okayama used open data from the national health insurance claims database to see what happened to prescribing in the three years on either side.
The national curve
Volume was counted in defined daily doses per 1,000 people per day, by age, sex and the 47 prefectures, with 2019 itself left out. Before the registry, use grew by 27% a year; after it, by 9%. At introduction the volume fell by 7%. Growth slowed in both sexes: for women the annual slope went from 1.40 to 1.13, for men from 1.23 to 1.08.
Split at age 20
Adults lost 19% at the start and kept growing, with the slope easing from 1.51 to 1.15. People under 20 lost 47% at once, and their slope went from 1.19 to 1.02. The authors tested whether the number of board-certified pediatricians per 100,000 residents explained regional differences; the correlation stayed weak in every year checked.
Who paid for control
My reading is that the registry was built against misuse, yet the measure barely slowed adult prescribing and nearly stopped growth among children and adolescents, the group most dependent on a small circle of specialists. The authors add that the COVID-19 pandemic began at the same moment and cut visits, which may have hit the young harder. For a family living far from a registered doctor and a registered pharmacy, the road to the same tablet got longer.
For a psychologist who works with families of children with ADHD, one question belongs early in the work: is the prescribing doctor registered, and is there a registered pharmacy within reach. Where regulators consider similar controls, the Japanese figures show which age group absorbs the cost first.
After registration became mandatory, prescriptions for people under 20 fell by 47% at once and then barely grew, while adult prescribing dropped by 19% and kept rising.
The data are aggregated, so new and continuing users cannot be told apart and treatment outcomes are not available. The design is ecological, with three yearly points on each side of the change, which coincided with the start of the COVID-19 pandemic. Data on psychiatrists with prescribing authority were not available by prefecture.
- ADHD
- methylphenidate
- drug regulation
- Japan
- access to treatment