title: Evaluating use patterns of and adherence to medications for benign prostatic hyperplasia.
abstract: OBJECTIVE
  We investigated adherence to benign prostatic hyperplasia medications in a California Medicaid population.
  
  
  METHODS
  Using California Medicaid data on 1995 to 2004 we identified adult males 40 years old or older with 1 or more diagnosis and 2 or more prescription fills for benign prostatic hyperplasia. Patients with 2 fills on the same day were assigned to the multiple medication cohort. Adherence was measured using the medication possession ratio for the index medication and the proportion of days covered for any benign prostatic hyperplasia medication. Patients with a medication possession ratio or proportion of days covered of 0.8 or greater were considered adherent. A Cox proportional hazards model was used to assess the relative hazards associated with discontinuation. Multiple logistic regression was used to investigate factors associated with nonadherence or a benign prostatic hyperplasia related procedure.
  
  
  RESULTS
  Of the total population of 2,640 men 40% were adherent with any benign prostatic hyperplasia medication. A significantly greater proportion of patients using multiple medications and finasteride were adherent with any benign prostatic hyperplasia medication (62% and 55%, respectively, p <0.0001). Doxazosin, terazosin and tamsulosin use was associated with nonadherence (p = 0.008, 0.04 and 0.03, respectively). Younger patients and those changing medications were more likely to discontinue (p = 0.01 and <0.0001), while patients using multiple medications and those experiencing a gap were at lower risk for discontinuation (p = 0.01 and <0.0001, respectively). Predictors of a procedure included an index prescription in 1999 or later, a urologist visit and nonadherence to any benign prostatic hyperplasia medication (p = 0.01, <0.0001 and <0.0001, respectively).
  
  
  CONCLUSIONS
  Adherence to alpha-blockers was less than adherence to finasteride or multiple medications and nonadherence was significantly associated with a procedure. Interventions focused on improving adherence to benign prostatic hyperplasia medications are clearly needed.
authors.affiliation: Department of Clinical Pharmacy and Pharmaceutical Economics and Policy, University of Southern California, Los Angeles, California 90089, USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Nichol
authors.forename: Tara K
authors.initials: TK
authors.lastname: Knight
authors.forename: Joanne
authors.initials: J
authors.lastname: Wu
authors.forename: Richard
authors.initials: R
authors.lastname: Barron
authors.forename: David F
authors.initials: DF
authors.lastname: Penson
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000008:administration & dosage; D058891:5-alpha Reductase Inhibitors; D000328:Adult; D000367:Age Factors; D000368:Aged; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D018120:Finasteride / Q000008:administration & dosage*; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010349:Patient Compliance / Q000706:statistics & numerical data*; D010352:Patient Dropouts / Q000706:statistics & numerical data; D011336:Probability; D016016:Proportional Hazards Models; D011470:Prostatic Hyperplasia / Q000175:diagnosis / Q000188:drug therapy*; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index
chemical_list: D058891:5-alpha Reductase Inhibitors; D018120:Finasteride; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase