When EBM fuels confusion: central demyelinating disorders after hepatitis B vaccines as a case-in-point

Although evidence-based medicine (EBM) has been introduced 15-20 years ago as a new paradigm in order to root medical practice more deeply into scientific rationality, poor understanding of its principles often leads to a regrettable mistake: in the quest for “the best available evidence”, emphasis should be on “available” and not on “the best”.

Having missed this crucial point, most health professionals stand now their grounds in a naïve, but damaging contempt for every data which does not complies with the so-called “gold-standard” of prospective randomised controlled trials (RCTs).


  • a number of RCTs are simply not reliable in the way they were performed – as exemplified by the well-recognized fact that those supported by interested parties usually have more favorable issues than those supported by independent bodies;
  • RCTs are not always feasible, as is quite clear with contraceptives (for ethical reasons), or with some safety issues (which would require unrealistic sample sizes);
  • those who have the regulatory or financial responsibility for performing RCTs, (or, at least: investigations complying with a minimum of standards) may be reluctant to do so, as they may have good reasons to be anxious about the results.

Attached documents