The available evidence , predominantly from secondary -prevention observational studies , supports that dosages greater than 75 to 81 mg/d do not enhance efficacy , whereas larger dosages are associated with an increased incidence of bleeding events , primarily related to gastrointestinal tract toxicity .
CONCLUSIONS Currently available clinical data do not support the routine , long-term use of aspirin dosages greater than 75 to 81 mg/d in the setting of cardiovascular disease prevention .
Higher dosages , which may be commonly prescribed , do not better prevent events but are associated with increased risks of gastrointestinal bleeding
CONTEXT More than 50 million US adults take aspirin regularly for long-term prevention of cardiovascular disease , typically either 81 mg/d or 325 mg/d .
Controversy remains regarding the most appropriate long-term daily dose .
OBJECTIVE To review the mechanism of action of aspirin and the clinical literature for relationships among  aspirin dosage , efficacy , and safety .
EVIDENCE SYNTHESIS Although pharmacodynamic data demonstrate that long-term aspirin dosages as low as 30 mg/d are adequate to fully inhibit platelet thromboxane production , dosages as high as 1300 mg/d are approved for use .
Inflammation, aspirin, and the risk of cardiovascular disease in apparently healthy men.
BACKGROUND Inflammation may be important in the pathogenesis of atherothrombosis . We studied whether inflammation increases the risk of a first thrombotic event and whether treatment with aspirin decreases the risk . METHODS We measured plasma C-reactive protein , a marker for systemic inflammation , in 543 apparently healthy men participating in the Physicians ' Health Study in whom myocardial infa rct ion , stroke , or venous thrombosis subsequently developed , and in 543 study participants who did not report vascular disease during a follow-up period exceeding eight years . Subjects were r and omly assigned to receive aspirin or placebo at the beginning of the trial . RESULTS Base-line plasma C-reactive protein concentrations were higher among men who went on to have myocardial infa rct ion ( 1.51 vs. 1.13 mg per liter , P<0.001 ) or ischemic stroke ( 1.38 vs. 1.13 mg per liter , P=0.02 ) , but not venous thrombosis ( 1.26 vs. 1.13 mg per liter , P=0.34 ) , than among men without vascular events . The men in the quartile with the highest levels of C-reactive protein values had three times the risk of myocardial infa rct ion ( relative risk , 2.9 ; P<0.001 ) and two times the risk of ischemic stroke ( relative risk , 1.9 ; P=0.02 ) of the men in the lowest quartile . Risks were stable over long periods , were not modified by smoking , and were independent of other lipid-related and non-lipid-related risk factors . The use of aspirin was associated with significant reductions in the risk of myocardial infa rct ion ( 55.7 percent reduction , P=0.02 ) among men in the highest quartile but with only small , nonsignificant reductions among those in the lowest quartile ( 13.9 percent , P=0.77 ) . CONCLUSIONS The base-line plasma concentration of C-reactive protein predicts the risk of future myocardial infa rct ion and stroke . Moreover , the reduction associated with the use of aspirin in the risk of a first myocardial infa rct ion appears to be directly related to the level of C-reactive protein , raising the possibility that antiinflammatory agents may have clinical benefits in preventing cardiovascular disease
The available evidence , predominantly from secondary -prevention observational studies , supports that dosages greater than 75 to 81 mg/d do not enhance efficacy , whereas larger dosages are associated with an increased incidence of bleeding events , primarily related to gastrointestinal tract toxicity .
CONCLUSIONS Currently available clinical data do not support the routine , long-term use of aspirin dosages greater than 75 to 81 mg/d in the setting of cardiovascular disease prevention .
Higher dosages , which may be commonly prescribed , do not better prevent events but are associated with increased risks of gastrointestinal bleeding
CONTEXT More than 50 million US adults take aspirin regularly for long-term prevention of cardiovascular disease , typically either 81 mg/d or 325 mg/d .
Controversy remains regarding the most appropriate long-term daily dose .
OBJECTIVE To review the mechanism of action of aspirin and the clinical literature for relationships among  aspirin dosage , efficacy , and safety .
EVIDENCE SYNTHESIS Although pharmacodynamic data demonstrate that long-term aspirin dosages as low as 30 mg/d are adequate to fully inhibit platelet thromboxane production , dosages as high as 1300 mg/d are approved for use .