To the Editor Several issues may have compromised the validity of the meta-analysis on the use of aspirin for primary prevention of cardiovascular events.1
First, the authors excluded the Prevention and Progression of Arterial Disease and Diabetes (POPADAD) trial and the Thrombosis Prevention Trial (TPT) from the estimate of the pooled effect for the composite cardiovascular outcome. Although POPADAD, TPT, the Japanese Primary Prevention of Atherosclerosis With Aspirin for Diabetes (JPAD) trial, and the Aspirin for Asymptomatic Atherosclerosis (AAA) trial did not report the event rate for the composite cardiovascular outcome, it seems that for the JPAD and AAA trials, Dr Zheng and Mr Roddick calculated the composite outcome by adding events for individual outcomes (stroke/cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke). The POPADAD and TPT investigators also reported event rates for individual outcomes, which the authors could have added to calculate the composite outcome. To maintain consistency, the authors either should have used only trials that reported event rates for the composite outcome or should have included all trials by calculating the composite outcome from individual outcome events in the trials that did not report a composite outcome. Their selective use of data from some trials while excluding other relevant data could have introduced bias and potentially compromised the validity of their analysis and conclusions.2
Shah R. Meta-analysis of Aspirin for Primary Prevention of Cardiovascular Events. JAMA. 2019;321(22):2244. doi:10.1001/jama.2019.4013
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