title: Trends in antithrombotic drug use and adherence to non-vitamin K oral anticoagulants in the Netherlands.
abstract: BACKGROUND
  Non-vitamin K oral anticoagulants (NOACs) became available in the Netherlands in 2008, providing another antithrombotic treatment besides vitamin K antagonists (VKAs) and antiplatelet agents (APAs).
  
  
  OBJECTIVE
  To describe the patterns of antithrombotic drug use between 2008 and 2013 by examination of dispensing data form community pharmacies in the Netherlands; to determine the concomitant use of NOACs with VKAs and APAs and switching between the drug classes; and to compare adherence to NOACs with adherence to APAs.
  
  
  METHODS
  An observational retrospective study was conducted using routinely collected dispensing data from Dutch community pharmacies.
  
  
  METHODS
  For each calendar year, the numbers of NOAC, VKA, and APA users were calculated. Adherence was determined for NOACs and APAs by the percentage of days covered by medication (PDC). Information on the prescribed daily dose of VKAs was unavailable.
  
  
  METHODS
  Comparison of age, sex, and co-medications of users of the three drug classes; concomitant use of different antithrombotic drug classes and switching between these in each year; and mean PDC and percentages of all users with a PDC above 80 %.
  
  
  RESULTS
  NOAC use increased during the study period to 29,687 users in 2013. In that year there were 484,024 VKA users and 1313,032 APA users. Compared with users of VKAs, NOAC users were slightly younger and more frequently used antiarrhythmic drugs and beta blockers as co-medications. Substantial numbers of patients were dispensed potentially harmful combinations in 2013: 820 subjects were dispensed NOACs together with VKAs, and 684 subjects were dispensed NOACs, VKAs, and APAs concomitantly. Mean adherence to NOACs was 84.2 % compared with 87.3 % to APA. One in four NOAC users had a PDC lower than 80 % compared with one in five APA users.
  
  
  CONCLUSIONS
  Our findings show increasing use of NOACs by outpatients. The number of patients taking potentially harmful combinations of antithrombotic drugs was substantial. Adherence to NOACs in daily practice may be suboptimal to prevent thrombotic events.
authors.affiliation: Royal Dutch Pharmacists Association (KNMP), 2514JL, The Hague, The Netherlands.|Division of Pharmacoepidemiology and Clinical Pharmacology, Faculty of Science, Utrecht Institute of Sciences, Utrecht University, PO Box 80082, 3508 TB, Utrecht, The Netherlands.
authors.forename: Susan
authors.initials: S
authors.lastname: Hanemaaijer
authors.affiliation: Royal Dutch Pharmacists Association (KNMP), 2514JL, The Hague, The Netherlands.
authors.forename: Fong
authors.initials: F
authors.lastname: Sodihardjo
authors.affiliation: Royal Dutch Pharmacists Association (KNMP), 2514JL, The Hague, The Netherlands.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Horikx
authors.affiliation: Department of IQ Healthcare, Radboud Institute for Health Sciences, Radboud University Medical Centre, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Michel
authors.initials: M
authors.lastname: Wensing
authors.affiliation: Royal Dutch Pharmacists Association (KNMP), 2514JL, The Hague, The Netherlands.|Department of Clinical Pharmacy, Radboud University Medical Centre, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Peter A G M
authors.initials: PA
authors.lastname: De Smet
authors.affiliation: Division of Pharmacoepidemiology and Clinical Pharmacology, Faculty of Science, Utrecht Institute of Sciences, Utrecht University, PO Box 80082, 3508 TB, Utrecht, The Netherlands.
authors.forename: Marcel L
authors.initials: ML
authors.lastname: Bouvy
authors.affiliation: Royal Dutch Pharmacists Association (KNMP), 2514JL, The Hague, The Netherlands. martina.teichert@radboudumc.nl.|Department of IQ Healthcare, Radboud Institute for Health Sciences, Radboud University Medical Centre, PO Box 9101, 6500 HB, Nijmegen, The Netherlands. martina.teichert@radboudumc.nl.
authors.forename: Martina
authors.initials: M
authors.lastname: Teichert
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage*; D000991:Antithrombins / Q000008:administration & dosage; D004363:Drug Utilization / Q000639:trends*; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D019338:Polypharmacy; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D014812:Vitamin K; D016903:Drug Monitoring
chemical_list: D000925:Anticoagulants; D000991:Antithrombins; D005343:Fibrinolytic Agents; D014812:Vitamin K
keywords: Adherence; DOACs; Drug use patterns; NOACs; Netherlands; Non-vitamin K oral anticoagulants