title: Aspirin for primary prevention: yes or no?
abstract: OBJECTIVE
  To assess benefit versus harm of aspirin for cardiovascular disease (CVD) primary prevention by age group, gender and risk category and to interpret these results in light of current New Zealand CVD risk assessment and management guidelines.
  
  
  METHODS
  Rates of benefit (avoided vascular events) and harm (additional major extracranial bleeds) for each gender and age group were calculated from data from the six randomised controlled trials included in the Anti-Thrombotic Trialists' (ATT) Collaboration meta-analysis. These rates were applied to CVD risk categories to calculate the net benefit or net harm likely to occur from the use of aspirin in primary prevention of CVD as monotherapy and when added to lipid and blood pressure-loweringtherapies.
  
  
  RESULTS
  Benefits of aspirin monotherapy outweigh the harms for both men and women aged up to 80 years with calculated five-year CVD risk >15% in primary prevention. Harm may outweigh benefit for primary prevention for those over 80 years. For men 70-79 years the benefit of aspirin in primary prevention is marginal when added to lipid and blood pressure-lowering therapies.
  
  
  CONCLUSIONS
  The recent ATT Collaboration meta-analysis has raised doubts about the relative safety of aspirin in primary prevention of CVD. However, modelling by risk category and age group suggests that current guidelines are justified in recommending aspirin for primary prevention of CVD in those with five-year CVD risk > or = 15% up to the age of 80 years. For men 70-79, consider lipid and blood pressure-lowering therapies first then reassess whether aspirin adds additional net benefit.
authors.affiliation: Clinical Trials Research Unit, School of Population Health, The University of Auckland, Auckland, New Zealand. v.selak@ctru.auckland.ac.nz
authors.forename: Vanessa
authors.initials: V
authors.lastname: Selak
authors.forename: C Raina
authors.initials: CR
authors.lastname: Elley
authors.forename: Sue
authors.initials: S
authors.lastname: Wells
authors.forename: Anthony
authors.initials: A
authors.lastname: Rodgers
authors.forename: Norman
authors.initials: N
authors.lastname: Sharpe
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001241:Aspirin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D002318:Cardiovascular Diseases / Q000517:prevention & control*; D005194:Family Practice; D005260:Female; D006801:Humans; D000960:Hypolipidemic Agents / Q000627:therapeutic use; D008297:Male; D015201:Meta-Analysis as Topic; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D017410:Practice Guidelines as Topic; D011322:Primary Prevention / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors
chemical_list: D000959:Antihypertensive Agents; D000960:Hypolipidemic Agents; D010975:Platelet Aggregation Inhibitors; D001241:Aspirin