Metaanalysis Raises More Questions About Routine Use of Aspirin for Primary Prevention

Although aspirin can reduce the risk of cardiovascular (CV) events, the associated increase in bleeding suggests that it should not be used routinely in  people without prior CV disease, say the authors of a new meta-analysis published in Archives of Internal Medicine.

Sreenivasa Rao Kondapally Seshasai and colleagues combined data from 9 clinical studies including more than 100,000 participants who were followed for a mean of 6 years. They found a significant reduction in CV events, but not CV mortality, and an increased risk of important bleeding events:

  • CV Events: OR 0.90, CI 0.85-0.96, number needed to treat (NNT): 120
  • –Nonfatal MI: OR 0.80, CI 0.67-0.96, NNT: 162
  • –CV Death: OR 0.99, CI 0.85-1.15,
  • Nontrivial bleeding events: OR 1.31, CI, 1.14-1.50,  number needed to harm, 73

The authors concluded that in the absence of further studies identifying patients likely to benefit from aspirin therapy “a reappraisal of current guidelines appears to be warranted, particularly in countries where a large number of otherwise healthy adults are prescribed aspirin, since a significant proportion of them may develop bleeding complications.”

In an accompanying comment, Samia Mora agrees with the authors that routine use of aspirin for primary prevention should not be recommended. But, she writes, “it is reasonable to consider using aspirin for primary prevention in higher-risk individuals without known CVD (above 1% CVD event rate per year) if they are deemed to have a greater benefit to risk ratio and after taking into account patient preferences.”

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