title: Proportion and risk indicators of nonadherence to statin therapy: a meta-analysis.
abstract: BACKGROUND
  Nonadherence to chronic disease medications is important. A growing body of literature suggests that better delivery of established therapies would save more lives than would discovery of innovations. Our first objective was to quantify the proportion of adherence to statin medications. The second objective was to provide estimates of risk indicators associated with nonadherence to statin medications.
  
  
  METHODS
  We performed a systematic literature review and meta-analysis of all studies published between database inception and June of 2011 that reviewed adherence, and risk indicators associated with nonadherence, to statin medications.
  
  
  RESULTS
  In the end, 67 studies met our inclusion and exclusion criteria and passed our methodological-quality evaluation. Among observational studies, 49.0% (95% confidence interval [CI], 48.9%-49.2%) of patients were adherent to statin medications at 1 year of follow-up. Among randomized trials, 90.3% (95% CI, 89.8%-90.8%) of patients were adherent to statin medications at 1 year of follow-up. The association between 147 variables and adherence to statin medications was determined. After meta-analysis, only 6 variables were associated with nonadherence to statin medications: primary prevention (rate ratio = 1.52; 95% CI, 1.50-1.53); new statin users (rate ratio = 1.46; 95% CI, 1.33-1.61); copayment (rate ratio = 1.28; 95% CI, 1.09-1.50; lower income status (rate ratio = 1.26; 95% CI, 1.16-1.37); fewer than 2 lipid tests performed (rate ratio = 1.38; 95% CI, 1.16-1.64), and not having hypertension (rate ratio = 1.16; 95% CI, 1.12-1.21).
  
  
  CONCLUSIONS
  This study provides some insight into the extent of nonadherence by study type along with 6 risk indicators associated with nonadherence to statin medications.
authors.affiliation: College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. mark.lemstra@usask.ca
authors.forename: Mark
authors.initials: M
authors.lastname: Lemstra
authors.forename: David
authors.initials: D
authors.lastname: Blackburn
authors.forename: Alex
authors.initials: A
authors.lastname: Crawley
authors.forename: Ryan
authors.initials: R
authors.lastname: Fung
mesh_terms: D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality*; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage*; D015994:Incidence; D008297:Male; D020380:Needs Assessment; D010349:Patient Compliance / Q000706:statistics & numerical data; D018570:Risk Assessment; D012525:Saskatchewan; D016903:Drug Monitoring
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors