Graphical Abstract The ASCEND substudy: a summary of results of the observational association between U-TXM and clinical outcomes, and the randomized comparison of aspirin and placebo on U-TXM and clinical outcomes. Observational findings showed positive correlations between U-TXM and SVE-R, and U-TXM and major bleeding. In the randomized comparisons, patients were assigned to aspirin or placebo. Aspirin treatment blocks TXA2 synthesis and therefore reduces U-TXM.9 Aspirin treatment, compared with placebo, lowers TXA2 and reduces SVE-R, and higher U-TXM predicts SVE-R which is consistent with the observational finding. However, aspirin treatment, compared with placebo, lowers U-TXM and increases major bleeding, and U-TXM predicts major bleeding, which is inconsistent with the observational finding.7 Abbreviations: HR, hazard ratio; SVE-R, serious vascular events or revascularizations; TXA2, thromboxane A2; TXB2, thromboxane B2; U-TXM, urine 11-dehydro-thromboxane B2. Square brackets denote concentration The ASCEND substudy: a summary of results of the observational association between U-TXM and clinical outcomes, and the randomized comparison of aspirin and placebo on U-TXM and clinical outcomes. Observational findings showed positive correlations between U-TXM and SVE-R, and U-TXM and major bleeding. In the randomized comparisons, patients were assigned to aspirin or placebo. Aspirin treatment blocks TXA2 synthesis and therefore reduces U-TXM.9 Aspirin treatment, compared with placebo, lowers TXA2 and reduces SVE-R, and higher U-TXM predicts SVE-R which is consistent with the observational finding. However, aspirin treatment, compared with placebo, lowers U-TXM and increases major bleeding, and U-TXM predicts major bleeding, which is inconsistent with the observational finding.7 Abbreviations: HR, hazard ratio; SVE-R, serious vascular events or revascularizations; TXA2, thromboxane A2; TXB2, thromboxane B2; U-TXM, urine 11-dehydro-thromboxane B2. Square brackets denote concentration