title: Coping with changes in the Defined Daily Dose in a longitudinal drug consumption database.
abstract: OBJECTIVE
  To illustrate the best approach to accurate representation of temporal evolution of drug consumption, when confronted with changes over time in the Defined Daily Dose (DDD) measurement unit.
  
  
  METHODS
  As an example, drug consumption (2001-2005) at the University Hospital Rijeka was expressed with the corresponding DDD in each year; and with the DDD value of the last year of the observation time window. By visual appraisal, results with both methods were compared with the graph of drug consumption trends expressed in physical units (mg, IU, etc.).
  
  
  RESULTS
  Of 20 drugs for which the DDD value has changed in the 5 year period, 5 were used in Rijeka hospital: erythropoietin parenteral, budesonide nasal spray, repaglinide oral, amoxicillin with clavulanic acid parenteral, and fentanyl transdermal. Graphs for individual drugs with the year by year method showed artificial jerks in the years proceeding the year of DDD change. Representation of total hospital consumption did not differ notably with the two methods.
  
  
  CONCLUSIONS
  Drug consumption data should be calculated with the latest DDD value in the time window. The policy of the World Health Organisation to keep changes to the system of DDD to a minimum should be continued.
authors.affiliation: Department of Clinical Pharmacology, University Hospital Rijeka, Kresimirova 42, Rijeka, 51000, Croatia. vvlahovic@inet.hr
authors.forename: Vera
authors.initials: V
authors.lastname: Vlahović-Palcevski
authors.forename: Monja
authors.initials: M
authors.lastname: Gantumur
authors.forename: Nives
authors.initials: N
authors.lastname: Radosević
authors.forename: Goran
authors.initials: G
authors.lastname: Palcevski
authors.forename: Robert
authors.initials: R
authors.lastname: Vander Stichele
mesh_terms: D017523:Croatia; D003625:Data Collection / Q000379:methods*; D016208:Databases, Factual; D004363:Drug Utilization; D006801:Humans; D008137:Longitudinal Studies; D055553:Prescription Drugs / Q000008:administration & dosage*; D012107:Research Design
chemical_list: D055553:Prescription Drugs