Deviant patterns of methylphenidate use in adults: a Danish nationwide registry-based drug utilization study.
OBJECTIVE
Several survey studies have documented misuse of methylphenidate defined as the use of non-prescribed methylphenidate or use different from what was prescribed. We aimed to identify and characterize adults with deviant patterns of methylphenidate use in Denmark during 2007-2012. Further, we aimed to identify risk factors associated with deviant patterns of use.


METHODS
Based on individual-level prescription data, new users of methylphenidate were followed for one year after filling their first prescription on methylphenidate. Adult patients were identified with deviant patterns of use if they had ≥4 different prescribers and filled ≥1095 defined daily doses of methylphenidate during the year of follow-up. Risk factors were estimated by using logistic regression.


RESULTS
Among 20 829 new users of methylphenidate, we identified 82 (0.39%) patients displaying deviant patterns of use. Characteristics associated with deviant patterns of use included an initial prescription for extended-release methylphenidate (OR2 4.35), age 25-49 years at first prescription (OR2 2.49), general practitioners or hospital doctors as initial prescribers (OR2 3.06 and OR2 4.07) and prior use of drugs used in addictive disorders (OR2 2.08) or opioids (OR2 1.75). Sensitivity analyses revealed that the number of different prescribers alone does not seem to effectively identify deviant users of methylphenidate.


CONCLUSIONS
We have identified characteristics associated with deviant patterns of methylphenidate use. Our results do not allow us to conclude if deviant users truly represent medical misusers.
Clinical Pharmacology, Department of Public Health, University of Southern Denmark, Odense C, Denmark.
Lotte
L
Rasmussen
Centre of Public Health Sciences, Faculty of Medicine, University of Iceland, Reykjavík, Iceland.
Helga
H
Zoëga
Clinical Pharmacology, Department of Public Health, University of Southern Denmark, Odense C, Denmark.
Jesper
J
Hallas
Clinical Pharmacology, Department of Public Health, University of Southern Denmark, Odense C, Denmark.
Anton
A
Pottegård
D000328:Adult; D000367:Age Factors; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000627:therapeutic use*; D003692:Delayed-Action Preparations; D003718:Denmark; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D008774:Methylphenidate / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D063487:Prescription Drug Misuse / Q000706:statistics & numerical data*; D012042:Registries; D012307:Risk Factors; D055815:Young Adult
D000697:Central Nervous System Stimulants; D003692:Delayed-Action Preparations; D008774:Methylphenidate
ADHD; Denmark; database; doctor shopping; drug utilization; methylphenidate; pharmacoepidemiology; prescription drug misuse