title: Seasonal Patterns of Medications for Treating Attention-Deficit/Hyperactivity Disorder: Comparison of Methylphenidate and Atomoxetine.
abstract: OBJECTIVE
  Medication is a first-line effective treatment for attention-deficit/hyperactivity disorder (ADHD). Currently, immediate-release methylphenidate (IR-MPH), the osmotic, controlled-release formulation of methylphenidate (OROS-MPH), and atomoxetine (ATX) are the only 3 medications approved in Taiwan for the treatment of ADHD. Short-term discontinuation of ADHD treatment is often seen among patients undergoing drug therapy. The goal of this study was to evaluate potential seasonal patterns in ADHD prescriptions and compare the seasonal changes of IR-MPH, OROS-MPH, and ATX use.
  
  
  METHODS
  Taiwan's National Health Insurance database was used to gather information on patients diagnosed with ADHD (N = 145,269) from January 2000 to December 2011. The monthly data regarding person-days and receipt of treatment with IR-MPH, OROS-MPH, and ATX were analyzed. Time series analyses and autoregressive integrated moving average models were used to examine the seasonal patterns in person-days receiving ADHD pharmacotherapy. A general linear model with a post hoc test was used to determine the differences in monthly consumption of ADHD medications.
  
  
  RESULTS
  This study comprised 145,269 patients (mean age: 7.7 years; 78.6% were boys) diagnosed with ADHD. The prescriptions of IR-MPH (seasonal autoregressive: estimate [SE], 0.92 [0.04], t = 22.87, P < 0.001) and OROS-MPH (estimate [SE], 0.84 [0.09], t = 9.41, P < 0.001) both showed significant seasonal patterns, but ATX prescriptions did not (estimate [SE], 0.50 [0.55]; t = 0.90; P = 0.373). IR-MPH and OROS-MPH prescriptions shared similar seasonal trends. The mean person-days of consumption in July were lower than in other months, with the exception of February and August. Meanwhile, for ATX, the person-days of consumption in February were the lowest. The mean person-days in February were significantly lower than in March and May but did not differ from those in other months.
  
  
  CONCLUSIONS
  The seasonal patterns of IR-MPH and OROS-MPH use coincide with school holidays. These findings suggest that discontinuing a drug during the holiday period may be popular for people undergoing ADHD pharmacotherapy, especially with regard to methylphenidate prescriptions. However, additional research is necessary to determine whether temporary discontinuation of drug therapy is related to patient outcomes.
authors.affiliation: Community Medicine Research Center, Chang Gung Memorial Hospital, Keelung, Keelung, Taiwan; Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan.
authors.forename: Yu-Chiau
authors.initials: YC
authors.lastname: Shyu
authors.affiliation: Department of Psychiatry, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; Department of Psychiatry, College of Medicine and Hospital, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Sheng-Yu
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Institute of Statistical Science, Academia Sinica, Taipei, Taiwan.
authors.forename: Shin-Sheng
authors.initials: SS
authors.lastname: Yuan
authors.affiliation: Community Medicine Research Center, Chang Gung Memorial Hospital, Keelung, Keelung, Taiwan; Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chun-Ju
authors.initials: CJ
authors.lastname: Yang
authors.affiliation: Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei, Taiwan; Institute of Statistical Science, Academia Sinica, Taipei, Taiwan.
authors.forename: Kang-Chung
authors.initials: KC
authors.lastname: Yang
authors.affiliation: Department of Experimental Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas, United States.
authors.forename: Tung-Liang
authors.initials: TL
authors.lastname: Lee
authors.affiliation: Department of Child and Adolescent Psychiatry, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan. Electronic address: wangliangjen@gmail.com.
authors.forename: Liang-Jen
authors.initials: LJ
authors.lastname: Wang
mesh_terms: D000069445:Atomoxetine Hydrochloride / Q000008:administration & dosage*; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000627:therapeutic use; D002626:Chemistry, Pharmaceutical; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000008:administration & dosage* / Q000627:therapeutic use; D012621:Seasons; D013624:Taiwan
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate; D000069445:Atomoxetine Hydrochloride
keywords: ADHD; drug adherence; epidemiology; pharmacotherapy; stimulant