Objectives: To estimate the number of patients who started methylphenidate during childhood and continued treatment beyond the age of 18 years and to study the determinants that may be associated with continuing treatment. Methods: Patients 17 years of age and younger who have received at least one prescription of methylphenidate were identified in the Integrated Primary Care Information database (1996–2017). Logistic regression analyses were performed to assess the association between potential determinants and continuation with methylphenidate treatment at the age of 18 years. Results: Fifty-three percent of all methylphenidate users (n = 1020) continued their treatment after the age of 18 years. Patients were more likely to continue treatment with methylphenidate if they started treatment at the age of 15–17 years compared with patients of 11 years and younger (adjusted odds ratio [OR]: 5.74, 95% confidence interval [CI]: 1.48–22.31), if they had a medication possession ratio (MPR) between 0.80 and 1.00 compared with a low MPR (adjusted OR: 2.18, 95% CI: 1.23–3.85) and if they lived in an area with a medium level of urbanization (adjusted OR: 1.98, 95% CI: 1.06–3.69). Furthermore, a relatively high number of patients had a MPR >1.0 (24.8%), of whom 91.3% started their treatment when they were between 15 and 17 years of age. Conclusions: Methylphenidate treatment initiated during childhood was continued in half of the study population when reaching the age of 18, where adolescents were more likely to continue treatment than young children. We also found that *25% of our study population had a MPR >1, mainly patients 15–17 years of age, which may suggest misuse or abuse of methylphenidate.

Additional Metadata
Keywords children, ADHD, methylphenidate, adulthood, continue, off-label
Persistent URL dx.doi.org/10.1089/cap.2018.0170, hdl.handle.net/1765/116865
Journal Journal of Child and Adolescent Psychopharmacology
Citation
Cheung, K, Verhamme, K.M.C, Herings, R, Visser, L.E, & Stricker, B.H.Ch. (2019). Methylphenidate Treatment Initiated During Childhood Is Continued in Adulthood in Half of the Study Population. Journal of Child and Adolescent Psychopharmacology. doi:10.1089/cap.2018.0170