title: Clopidogrel discontinuation after acute coronary syndromes: frequency, predictors and associations with death and myocardial infarction--a hospital registry-primary care linked cohort (MINAP-GPRD).
abstract: OBJECTIVE
  Adherence to evidence-based treatments and its consequences after acute myocardial infarction (MI) are poorly defined. We examined the extent to which clopidogrel treatment initiated in hospital is continued in primary care; the factors predictive of clopidogrel discontinuation and the hazard of death or recurrent MI.
  
  
  RESULTS
  We linked the Myocardial Ischaemia National Audit Project registry and the General Practice Research Database to examine adherence to clopidogrel in primary care among patients discharged from hospital after MI (2003-2009). Hospital Episode Statistics and national mortality data were linked, documenting all-cause mortality and non-fatal MI. Of the 7543 linked patients, 4650 were prescribed clopidogrel in primary care within 3 months of discharge. The adjusted odds of still being prescribed clopidogrel at 12 months were similar following non-ST-elevation myocardial infarction (NSTEMI) 53% (95% CI, 51-55) and ST-elevation myocardial infarction (STEMI) 54% (95% CI, 52-56), but contrast with statins: NSTEMI 84% (95% CI, 82-85) and STEMI 89% (95% CI, 87-90). Discontinuation within 12 months was more frequent in older patients [>80 vs. 40-49 years, adjusted hazard ratio (HR) 1.50 (95% CI, 1.15-1.94)] and with bleeding events [HR 1.34 (95% CI, 1.03-1.73)]. 18.15 patients per 100 person-years (95% CI, 16.83-19.58) died or experienced non-fatal MI in the first year following discharge. In patients who discontinued clopidogrel within 12 months, the adjusted HR for death or non-fatal MI was 1.45 (95% CI, 1.22-1.73) compared with untreated patients, and 2.62 (95% CI, 2.17-3.17) compared with patients persisting with clopidogrel treatment.
  
  
  CONCLUSIONS
  This is the first study to use linked registries to determine persistence of clopidogrel treatment after MI in primary care. It demonstrates that discontinuation is common and associated with adverse outcomes.
authors.affiliation: General Practice Research Database,  Medicines and Healthcare products Regulatory Agency, 151 Buckingham Palace Road, London SW1W 9SZ,  UK.
authors.forename: Rachael
authors.initials: R
authors.lastname: Boggon
authors.forename: Tjeerd P
authors.initials: TP
authors.lastname: van Staa
authors.forename: Adam
authors.initials: A
authors.lastname: Timmis
authors.forename: Harry
authors.initials: H
authors.lastname: Hemingway
authors.forename: Kausik K
authors.initials: KK
authors.lastname: Ray
authors.forename: Alan
authors.initials: A
authors.lastname: Begg
authors.forename: Cathy
authors.initials: C
authors.lastname: Emmas
authors.forename: Keith A A
authors.initials: KA
authors.lastname: Fox
mesh_terms: D054058:Acute Coronary Syndrome / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000077144:Clopidogrel; D015331:Cohort Studies; D016757:Death, Sudden, Cardiac / Q000209:etiology; D005260:Female; D058006:General Practice / Q000706:statistics & numerical data; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data; D012042:Registries; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine