Effects of low-dose aspirin on serum C-reactive protein and thromboxane B-2 concentrations: A placebo-controlled study using a highly sensitive C-reactive protein assay

Objectives We performed a placebo-controlled study to evaluate the effect o f low-dose aspirin on serum C-reactive protein (CRP) levels. Background Elevated circulating concentrations of CRP, an inflammatory mark er, increase the risk of thrombotic cardiovascular diseases such as myocard ial infarction (MI). Moreover, low-dose aspirin therapy has been reported t o be more effective in preventing MI in men with higher CRP levels than it is in those with lower levels, raising the possibility that aspirin prevent s thrombosis by reducing vascular inflammation. The effect of low-dose aspi rin therapy on serum CRP levels in men has been addressed recently, but the results of the two studies conflict. Methods Effects of aspirin (81 mg every day or 325, 81 or 40 mg every-third -clay given for 32 days) on serum CRP, using a highly-sensitive assay and o n serum platelet-cyclo-oxygenase(COX)1-derived thromboxane (Tx) B-2 concent rations were studied simultaneously in 57 healthy volunteers (30 men and 27 women). Results Trough platelet COX-1-derived serum Tx B-2 concentrations decreased by 100% with daily aspirin and by 90%, 84% and 78% with 325, 81 and 40 mg aspirin every-third-day (p < 0.001). However, there were no significant cha nges in serum CRP levels from baseline with daily low-dose aspirin therapy, with any of the every-third-day aspirin regimens or with placebo treatment . Conclusions Low doses of aspirin that markedly inhibit platelet COX-1 activ ity, as manifested by a profound decline in platelet-derived serum Tx B-2 c oncentrations, have no detectable effect on serum CRP levels in healthy men and women. (J Am Coll Cardiol 2001;37: 2036-41) (C) 2001 by the American C ollege of Cardiology.