Heterogeneity is often an important problem in meta-analyses and complicates drawing overall conclusions. As correctly pointed out by Fontana and Reny in their letter and also acknowledged in the “Comment” section of our systematic review on the clinical consequences of laboratory aspirin resistance,1 the studies in our review are heterogeneous in many ways, regarding, for example, study population and definition of aspirin resistance. This is probably reflected by the statistical heterogeneity present in the pooled analysis, though, parenthetically, it would not be ruled out by statistical homogeneity.
Snoep JD, Hovens MMC, Eikenboom JCJ, van der Bom JG, Huisman MV. Is Aspirin Resistance Due to Noncompliance?—Reply. Arch Intern Med. 2008;168(5):550. doi:10.1001/archinte.168.5.550-a