Frank Veith writes that the results of good randomized controlled trials published in leading peer-reviewed journals, like New England Journal of Medicine, Lancet, the Journal of Vascular Surgery, Circulation, and many others, are considered as the best possible basis for good medical practice, but that several limitations decrease their value.

He provides a series of examples of flaws and weaknesses in published randomized controlled trials that render them less applicable or invalid:

1. Treatment under evaluation technology or patient selection improves
2. Progress in control treatment
3. Poor or unrepresentative patient selection
4. Inadequate experience or competence of operators
5. Imperfect randomization
6. Nonapplicability to reality
7. Idiosyncratic flaws: delay in application of treatment
8. Imperfect population randomized
9. Inappropriate primary end points

He concludes that the examples show that unjustified conclusions sometimes can be reached in leading peer-reviewed journals, and that this occurs because of flaws in the RCTs, unrecognized author bias, or both, and that the unjustified conclusions and the trials on which they are based can be further misinterpreted and lead ro even more erroneous or unjustified conclusions. Being aware of the flaws that RCTs may have is important.


1. Veith FJ. How can good randomized controlled trials in leading journals be so misinterpreted? J Vasc Surg 2013;57:3S-7S.