title: A retrospective analysis of extended-interval dosing and the impact on bisphosphonate compliance in the US Military Health System.
abstract: This study evaluated whether patients treated with bisphosphonates in the US Military Health System were more compliant with treatment given monthly versus weekly. While medication compliance did improve with treatment given monthly, overall compliance with bisphosphonates was still suboptimal suggesting the need for further strategies to improve compliance with treatment for osteoporosis.
  
  
  BACKGROUND
  The study objective was to evaluate the relationship between bisphosphonate dosing interval and medication compliance among new users initiating oral bisphosphonates.
  
  
  METHODS
  We conducted a retrospective observational cohort study of administrative claims data in the US Military Health System to examine medication compliance among 22,363 new users of oral bisphosphonates starting weekly (68%) or monthly (32%) therapy. Medication compliance during the first year of treatment was measured using two methods: (1) medication possession ratio (MPR) with compliance defined as ≥80% of days covered and (2) time to first gap of more than 30 days following initiation. Logistic regression and a proportional hazards model were used to detect differences in medication compliance between cohorts.
  
  
  RESULTS
  After the first year of therapy, 57% of subjects were not compliant with bisphosphonates (MPR <80%), while 84% experienced a gap in treatment of more than 30 days. After adjustment for study covariates, the odds of a patient being compliant with treatment was 21% higher among monthly users compared to weekly users (OR 1.207, 95% confidence interval (CI) 1.119-1.257). Similarly, the risk of experiencing a 30-day gap in treatment was 6% lower among monthly users compared to weekly users (HR 0.934, 95% CI 0.905-0.964).
  
  
  CONCLUSIONS
  Patients receiving oral bisphosphonates on a monthly basis showed higher rates of medication compliance compared to weekly dosing in our study. However, compliance with bisphosphonates among all new users was suboptimal, suggesting the need for improved strategies to enhance compliance with oral bisphosphonates in the US Military Health System.
authors.affiliation: TRICARE Management Activity (TMA), Pharmacoeconomic Center, 4130 Stanley Road, Bldg 1000, Fort Sam Houston, San Antonio, TX 78234, USA. josh.devine@amedd.army.mil
authors.forename: J
authors.initials: J
authors.lastname: Devine
authors.forename: S
authors.initials: S
authors.lastname: Trice
authors.forename: Z
authors.initials: Z
authors.lastname: Finney
authors.forename: S
authors.initials: S
authors.lastname: Yarger
authors.forename: E
authors.initials: E
authors.lastname: Nwokeji
authors.forename: A
authors.initials: A
authors.lastname: Linton
authors.forename: W
authors.initials: W
authors.lastname: Davies
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050071:Bone Density Conservation Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D004164:Diphosphonates / Q000008:administration & dosage* / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008887:Military Medicine / Q000706:statistics & numerical data; D010024:Osteoporosis / Q000188:drug therapy*; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy; D012189:Retrospective Studies; D014481:United States; D055815:Young Adult; D016903:Drug Monitoring
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates