title: Medication adherence, first episode duration, overall duration and time without therapy: the example of bisphosphonates.
abstract: OBJECTIVE
  We aimed to determine the duration of first episode of therapy and overall therapy as well as time without treatment for bisphosphonates.
  
  
  METHODS
  Data were extracted from Department of Veterans' Affairs (DVA) dataset for those with at least one dispensing for a bisphosphonate between April 2001 and April 2007. Episodes of use were determined as the number of treatment days between the first and last prescription plus 35 days once a dispensing gap of 105 days had been reached, or where no treatment gaps were recorded, the study end date. Kaplan-Meier analyses were undertaken for the first episode of use, overall duration and time without treatment.
  
  
  RESULTS
  When considering only the duration of first episode, median bisphosphonate use was 1.19 years. The median duration extended to 3.27 years when all episodes of use were considered. Overall, 52.0% of subjects reached at least 3 years of treatment and 66.5% of existing users had a duration of at least 3 years. Median time without treatment was 1.65 years. Overall, 81% of the cohort had enough medicine dispensed to be considered adherent throughout their duration of use.
  
  
  CONCLUSIONS
  Over 50% of subjects and 66% of existing users had duration consistent with the minimum recommended. Adherence within an episode was high. The focus for improving duration of bisphosphonate use should be on reducing the time without treatment, rather than adherence at the time of use. Studies assessing only the first episode of use in new users of medicines may underestimate duration.
authors.affiliation: Quality Use of Medicines and Pharmacy Research Centre, Sansom Institute, University of South Australia, Australia. libby.roughead@unisa.edu.au
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Roughead
authors.forename: Emmae
authors.initials: E
authors.lastname: Ramsay
authors.forename: Kym
authors.initials: K
authors.lastname: Priess
authors.forename: John
authors.initials: J
authors.lastname: Barratt
authors.forename: Philip
authors.initials: P
authors.lastname: Ryan
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Gilbert
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016208:Databases, Factual; D004164:Diphosphonates / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D013997:Time Factors; D014481:United States; D014728:Veterans; D016903:Drug Monitoring
chemical_list: D004164:Diphosphonates