title: Cardiovascular event rates in atorvastatin patients versus patients switching from atorvastatin to simvastatin.
abstract: OBJECTIVE
  Statin dose, adherence, and cardiovascular (CV) outcomes are important factors when considering switching statin therapies. The objective of the study was to compare CV event rates and risk in managed care patients receiving atorvastatin versus those switched to simvastatin from atorvastatin.
  
  
  METHODS
  Patients 18-64 years, with ≥3 continuous pharmacy claims for atorvastatin between 1/1/05-11/30/07 and ≥12 months pre- and ≥3 months post-index continuous eligibility were identified using HealthCore Integrated Research Database (HIRD). Patients were stratified into two cohorts: one continued atorvastatin without interruption and the other switched to simvastatin. Patients were matched 1:10 (continue atorvastatin/switch simvastatin) on five variables, excluding lipid parameters due to limited data availability. Descriptive statistics were reported for sample characteristics. A multivariate Cox proportional hazards model was developed to evaluate adjusted CV risk.
  
  
  RESULTS
  In total 73,960 atorvastatin patients and 7396 simvastatin-switch patients were analyzed. The mean age was 54 ± 7 years (both cohorts). Mean follow-up was 440 days for atorvastatin patients and 237 days for simvastatin-switch patients. Mean dose and therapy duration for atorvastatin was 20 mg and 321 days compared with 33 mg and 195 days for simvastatin-switch, respectively. Of the simvastatin-switch patients, 32% were switched to a less potent simvastatin dose (<2× prior atorvastatin dose). After adjusting for demographic/clinical characteristics, no significant differences were found in CV risk between cohorts.
  
  
  CONCLUSIONS
  Limitations include use of administrative claims data without lipid level laboratory results data and the length of follow-up which may not have been sufficient to demonstrate significant differences in event rates between groups.
  
  
  CONCLUSIONS
  In this managed care population, no significant differences were found in risk of CV events among patients switching to simvastatin compared to patients continuing atorvastatin. Switched patients may differ from controls for reasons not captured in the database.
authors: Emory University, Office of Health Promotion and Disease Prevention, Atlanta, GA 30303, USA. tjaco02@emory.edu
authors: Terry A
authors: TA
authors: Jacobson
authors: Debra A
authors: DA
authors: Wertz
authors: Andreas
authors: A
authors: Kuznik
authors: Mark
authors: M
authors: Cziraky
mesh_terms: D000293:Adolescent; D000328:Adult; D000924:Anticholesteremic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D000069059:Atorvastatin; D002319:Cardiovascular System / Q000187:drug effects*; D005260:Female; D006538:Heptanoic Acids / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D006949:Hyperlipidemias / Q000188:drug therapy; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011758:Pyrroles / Q000009:adverse effects / Q000627:therapeutic use*; D012189:Retrospective Studies; D012306:Risk; D019821:Simvastatin / Q000009:adverse effects / Q000627:therapeutic use*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000924:Anticholesteremic Agents; D006538:Heptanoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011758:Pyrroles; D000069059:Atorvastatin; D019821:Simvastatin