title: The effect of switching on compliance and persistence: the case of statin treatment.
abstract: OBJECTIVE
  To determine the effect of switching drugs on the compliance and persistence of new statin users.
  
  
  METHODS
  Retrospective database analysis of pharmacy claims provided by a large pharmacy benefit manager. The study sample consisted of 38 866 new statin users 18 to 65 years old beginning treatment with atorvastatin calcium, fluvastatin sodium, lovastatin, pravastatin sodium, or simvastatin.
  
  
  METHODS
  Compliance was measured by the "medication possession ratio," and persistence was measured by the time to discontinuation. Switching rates were derived from the proportions of patients filling a prescription other than the initial statin.
  
  
  RESULTS
  Patients who switched statins were less compliant by 18.9% (odds ratio, 0.81; P < .001), as defined by the probability of having a medication possession ratio of 0.8 or higher, and were less persistent by 20.9% to 48.3% (P < .001) depending on the gap length used to define discontinuation.
  
  
  CONCLUSIONS
  Switching statins substantially reduces the likelihood that patients will be compliant and remain on treatment long enough to obtain the full benefit of statin treatment. To ensure better compliance, special care should be given to patients who change drugs.
authors.affiliation: Department of Pharmaceutical Economics and Policy, School of Pharmacy; University of Southern California, 1540 East Alcazar Street, CHP 140, Los Angeles, CA 90033, USA. thiebaud@usc.edu
authors.forename: Patrick
authors.initials: P
authors.lastname: Thiebaud
authors.forename: Bimal V
authors.initials: BV
authors.lastname: Patel
authors.forename: Michael B
authors.initials: MB
authors.lastname: Nichol
authors.forename: David M
authors.initials: DM
authors.lastname: Berenbeim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000924:Anticholesteremic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002140:California; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D006937:Hypercholesterolemia / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D012189:Retrospective Studies
chemical_list: D000924:Anticholesteremic Agents; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors