title: Methylphenidate and the risk of psychotic disorders and hallucinations in children and adolescents in a large health system.
abstract: Previous studies have suggested that risk of psychotic events may be increased in children exposed to methylphenidate (MPH). However, this risk has not been fully examined, and the possibility of confounding factors has not been excluded. Patients aged 6-19 years who received at least one MPH prescription were identified using Hong Kong population-based electronic medical records on the Clinical Data Analysis and Reporting System (2001-2014). Using the self-controlled case series design, relative incidence of psychotic events was calculated comparing periods when patients were exposed to MPH with non-exposed periods. Of 20,586 patients prescribed MPH, 103 had an incident psychotic event; 72 (69.9%) were male and 31 (30.1%) female. The mean age at commencement of observation was 6.95 years and the mean follow-up per participant was 10.16 years. On average, each participant was exposed to MPH for 2.17 years. The overall incidence of psychotic events during the MPH exposure period was 6.14 per 10,000 patient-years. No increased risk was found during MPH-exposed compared with non-exposed periods (incidence rate ratio (IRR) 1.02 (0.53-1.97)). However, an increased risk was found during the pre-exposure period (IRR 4.64 (2.17-9.92)). Results were consistent across all sensitivity analyses. This study does not support the hypothesis that MPH increases risk of incident psychotic events. It does indicate an increased risk of psychotic events before the first prescription of MPH, which may be because of an association between psychotic events and the behavioural and attentional symptoms that led to psychiatric assessment and initiation of MPH treatment.
authors.affiliation: Department of Pharmacology and Pharmacy, Centre for Safe Medication Practice and Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.|Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: K K C
authors.initials: KK
authors.lastname: Man
authors.affiliation: Division of Neuroscience, School of Medicine, University of Dundee, Dundee, UK.|Departments of Paediatrics and Psychiatry, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, VIC, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Coghill
authors.affiliation: Department of Pharmacology and Pharmacy, Centre for Safe Medication Practice and Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: E W
authors.initials: EW
authors.lastname: Chan
authors.affiliation: Department of Pharmacology and Pharmacy, Centre for Safe Medication Practice and Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: W C Y
authors.initials: WC
authors.lastname: Lau
authors.affiliation: CANDAL (Centre for ADHD and Neuro-developmental Disorders across the Lifespan), Institute of Mental Health, Nottingham, UK.|Division of Psychiatry and Applied Psychology, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: C
authors.initials: C
authors.lastname: Hollis
authors.affiliation: CANDAL (Centre for ADHD and Neuro-developmental Disorders across the Lifespan), Institute of Mental Health, Nottingham, UK.|Division of Psychiatry and Applied Psychology, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: E
authors.initials: E
authors.lastname: Liddle
authors.affiliation: Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Banaschewski
authors.affiliation: School of Pharmacy, University College Cork, Cork, Ireland.
authors.forename: S
authors.initials: S
authors.lastname: McCarthy
authors.affiliation: Department of Paediatrics and Adolescents Medicine, University Hospital Erlangen, Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Neubert
authors.affiliation: CANDAL (Centre for ADHD and Neuro-developmental Disorders across the Lifespan), Institute of Mental Health, Nottingham, UK.|Division of Psychiatry and Applied Psychology, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: K
authors.initials: K
authors.lastname: Sayal
authors.affiliation: Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: P
authors.initials: P
authors.lastname: Ip
authors.affiliation: Department of Pharmacology and Pharmacy, Centre for Safe Medication Practice and Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.|Centre for Paediatric Pharmacy Research, Research Department of Practice and Policy, UCL School of Pharmacy, London, UK.
authors.forename: I C K
authors.initials: IC
authors.lastname: Wong
mesh_terms: D000293:Adolescent; D002648:Child; D057286:Electronic Health Records; D005260:Female; D005500:Follow-Up Studies; D006212:Hallucinations / Q000139:chemically induced*; D006723:Hong Kong; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000009:adverse effects* / Q000627:therapeutic use*; D011605:Psychoses, Substance-Induced / Q000209:etiology*; D012306:Risk
chemical_list: D008774:Methylphenidate