title: Medication adherence and healthcare costs among fibromyalgia patients treated with duloxetine.
abstract: OBJECTIVE
  The study aims to examine predictors associated with duloxetine adherence and its association with healthcare costs among fibromyalgia patients.
  
  
  METHODS
  Administrative claims from both commercially and Medicare supplemental-insured fibromyalgia patents aged 18+ who initiated duloxetine in 2006 were analyzed. Initiation was defined as a 90-day clean period without duloxetine. The dispense date of the first duloxetine prescription was denoted as the index date. Two cohorts were constructed based on duloxetine adherence over the 12-month postindex period (high adherence as medication possession ratio ≥0.8). Predictors of high adherence were examined via logistic regression. Generalized linear regressions were performed to estimate the association between duloxetine adherence and healthcare costs.
  
  
  RESULTS
  A total of 4,869 commercially and 566 Medicare supplemental-insured fibromyalgia patients were identified. Two-thirds of patients had low adherence. Higher duloxetine average daily dose (ADD) was associated with increased adherence (reference group=30mg; Commercial: Odds ratio [OR]=3.03, 2.40, and 3.73 for 31 to 59mg, 60mg, and >60mg, respectively, all P<0.05; Medicare supplemental: OR=3.11, 2.33, and 4.76 for 31 to 59mg, 60mg, and >60mg, respectively, all P<0.05). Commercially insured patients with high adherence had significantly lower total healthcare costs than low-adherence patients (-$1,164, P<0.05), primarily because of lower inpatient (-$2,222, P<0.05) and outpatient (-$1,075, P<0.05) costs. Medicare supplemental-insured patients with high adherence had similar overall and inpatient costs, but significantly lower outpatient costs (-$2,025, P<0.05).
  
  
  CONCLUSIONS
  Fibromyalgia patients with higher duloxetine ADD were more likely to adhere to the therapy. High duloxetine adherence was associated with lower (Commercial) or similar (Medicare supplemental) healthcare costs.
authors.affiliation: Global Health Outcomes, Eli Lilly and Company, Indianapolis, Indiana 46221, USA. zhao_yang_yz@lilly.com
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Shih-Yin
authors.initials: SY
authors.lastname: Chen
authors.forename: Ning
authors.initials: N
authors.lastname: Wu
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Fraser
authors.forename: Luke
authors.initials: L
authors.lastname: Boulanger
mesh_terms: D000328:Adult; D000700:Analgesics / Q000191:economics / Q000627:therapeutic use*; D000068736:Duloxetine Hydrochloride; D005260:Female; D005356:Fibromyalgia / Q000188:drug therapy* / Q000191:economics; D017048:Health Care Costs; D006801:Humans; D008297:Male; D006278:Medicare / Q000191:economics; D055118:Medication Adherence; D008875:Middle Aged; D013876:Thiophenes / Q000191:economics / Q000627:therapeutic use*; D014481:United States
chemical_list: D000700:Analgesics; D013876:Thiophenes; D000068736:Duloxetine Hydrochloride