Relative Versus Absolute Benefits and Harm of Dual Antiplatelet Therapy After Drug-Eluting Stenting


      Much controversy exists about the duration of dual antiplatelet therapy (DAPT) after drug-eluting stenting for coronary heart disease. Findings from the recently published double blind, multicentre, DAPT trial involving 9961 randomised patients, sheds light on the balance between the benefits and harm of extending such treatment from 12 to 30 months expressed in relative terms.1 However, to appreciate the true clinical significance of its results, requires that absolute effects also be considered.


      As previously described,2 we therefore derived unadjusted relative risk (RR) and number needed to treat (NNT)/year values for extended duration dual antiplatelet therapy (clopidogrel or prasugrel + aspirin) versus aspirin only for important reported endpoints, based on the published DAPT trial results.


      See table.
      Negative NNTs indicate harm; ∞ Definite or probable; # MACCE Major adverse cardiovascular or cerebrovascular event (death, myocardial infarct, stroke).


      These parameters for extended duration DAPT indicate statistically significant relative and absolute benefits with respect to stent thrombosis and major cardiovascular and cerebrovascular events, though in absolute terms they were modest. Regarding harms, the risk of severe/moderate bleeds was significant (though modest in absolute terms), but there was also a small though not quite statistically significant increase in all-cause deaths.


      1. Mauri L et al, 2014. DOI:10.1056 NEJMoa1409312.
      2. Kumana CR et al, 1999. JAMA 282:1899–1901.