title: Associations between prescription copayment levels and β-blocker medication adherence in commercially insured heart failure patients 50 years and older.
abstract: BACKGROUND
  High prescription copayments may create barriers to care, resulting in medication nonadherence. Although many studies have examined these associations in commercially insured patients with chronic disease, few have examined β-blocker effects in heart failure patients.
  
  
  OBJECTIVE
  Associations between β-blocker prescription copayment levels and medication nonadherence were examined within commercially insured beneficiaries with a diagnosis of heart failure.
  
  
  METHODS
  Heart failure patients were identified as those with at least 1 inpatient claim or 2 outpatient claims with an associated International Classification of Diagnosis, 9th Edition (ICD-9) code of 428.x, in addition to those with at least 2 β-blocker claims. Copayment levels were defined in using $5.00 (USD) interval categories, and adherence was defined using the medication possession ratio (MPR). Ordinary least squares (OLS), fixed effects (FE), and random effect (RE) models were used to estimate associations between copayment level and MPR. Logistic regression was used to estimate the probability of nonadherence (MPR < 0.80) conditional upon copayment level. Regressions controlled for patient demographics, health status, prior hospitalizations, and concomitant medication use.
  
  
  RESULTS
  The highest β-blocker copayment level ($26+) had an average MPR that was 0.07 (95% CI, -0.11 to -0.03), 0.08 (95% CI, -0.12 to -0.04), and 0.09 (95% CI, -0.17 to -0.02) units lower than β-blocker copayment level ($0 to $1) in the OLS, RE, and FE models, respectively. Copayment levels $21-$25 and $26+ were significantly associated with an increased risk of medication nonadherence (OR = 1.64; 95% CI, 1.1-2.4; and OR = 2.5; 95%, CI 1.6-4, respectively).
  
  
  CONCLUSIONS
  Commercially insured heart failure patients aged ≥50 years who are prescribed higher costing β-blockers may have up to an average 9% decrease in annual β-blocker medication supply as well as an increased risk of nonadherence (MPR <0.80). Results need to be interpreted with caution given the potential of selection bias due to selective prescribing. Associations between copayment levels and nonadherence need to be further explored given the adverse health consequences of nonadherence to β-blockers.
authors.affiliation: University of Missouri-Kansas City School of Pharmacy, Kansas City, Missouri 64108-2718, USA. pattersonmar@umkc.edu
authors.forename: Mark E
authors.initials: ME
authors.lastname: Patterson
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Blalock
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Smith
authors.forename: Michael D
authors.initials: MD
authors.lastname: Murray
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000191:economics / Q000627:therapeutic use*; D000368:Aged; D003669:Deductibles and Coinsurance; D005260:Female; D006333:Heart Failure / Q000188:drug therapy*; D006801:Humans; D007348:Insurance, Health; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance
chemical_list: D000319:Adrenergic beta-Antagonists