title: Channeling and adherence with alendronate and risedronate among chronic glucocorticoid users.
abstract: BACKGROUND
  Despite the efficacy of bisphosphonates to reduce fractures in high risk populations, bisphosphonate adherence among chronic glucocorticoid users has received limited attention. Moreover, perceived differences in GI tolerability may lead physicians to preferentially prescribe particular bisphosphonates.
  
  
  METHODS
  Among chronic glucocorticoid users (>60 days of therapy) enrolled in managed care, we identified individuals initiating therapy with alendronate or risedronate during 2001-2004. Multivariable logistic regression and proportional hazards models were used to examine factors associated with channeling patients to risedronate (versus alendronate) and with discontinuation (>3-month gap without refill). The Medication Possession Ratio (MPR) was calculated as the filled days of medication divided by the interval of time between prescriptions.
  
  
  RESULTS
  Of 1,158 glucocorticoid users initiating bisphosphonate therapy, demographic characteristics of alendronate users (n=754) and risedronate users (n=404) were similar for age (mean 53 years) and gender (approximately 80% female). Past history of a GI symptom or event was associated with risedronate receipt (OR=2.24, 95% CI 1.15-4.35). After multivariable adjustment, rates of discontinuation (mean time to discontinuation approximately 18 months) and adherence (mean MPR=73%) were similar between users of the two bisphosphonates. Younger age, greater medical comorbidity, and lack of BMD testing were significantly associated with discontinuation.
  
  
  CONCLUSIONS
  Overall persistence rates were suboptimal for bisphosphonate use among chronic glucocorticoids users and did not differ significantly by drug. Newer strategies to promote long-term adherence are needed to improve osteoporosis therapeutic effectiveness.
authors.affiliation: Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, FOT 820, 510 20th Street South, 35294, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Curtis
authors.forename: A O
authors.initials: AO
authors.lastname: Westfall
authors.forename: J J
authors.initials: JJ
authors.lastname: Allison
authors.forename: A
authors.initials: A
authors.lastname: Freeman
authors.forename: K G
authors.initials: KG
authors.lastname: Saag
mesh_terms: D000328:Adult; D000368:Aged; D019386:Alendronate / Q000009:adverse effects / Q000627:therapeutic use*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D012968:Etidronic Acid / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D005938:Glucocorticoids / Q000009:adverse effects*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000517:prevention & control*; D010349:Patient Compliance; D016016:Proportional Hazards Models; D000068296:Risedronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D005938:Glucocorticoids; D000068296:Risedronic Acid; D012968:Etidronic Acid; D019386:Alendronate