Georg Ivanovas From Autism to Humanism - systems theory in medicine

2.5 The limits of evidence based medicine

previous -- home -- content -- next

c) validity and the consequences for practice

‘Pragmatical trails’ (Godwin et al 2003) and cohort studies (Gurwitz et al 2005) have been introduced because normal RCTs are only true under ideal conditions but are of reduced value under other conditions: “Controlled clinical trials of health care interventions are either explanatory or pragmatic. Explanatory trials test whether an intervention is efficacious; that is, whether it can have a beneficial effect in an ideal situation. Pragmatic trials measure effectiveness; they measure the degree of beneficial effect in real clinical practice. In pragmatic trials, a balance between external validity (generalizability of the results) and internal validity (reliability or accuracy of the results) needs to be achieved” (Godwin et al 2003). But pragmatical trails and cohort studies do not solve the basic problems of trials.

Even an effective remedy will fail, if it works only in a few patients. ”A weak effect with little variability is ‘significant’, whereas a strong effect with considerable variability may not be” (Spiro 1997: 43). Even if a remedy has strong effects but is investigated for other purposes, there will be no result. Viagra failed to prove effective in an angina-pectoris-trail. Only the refusal of the test persons to return the drug and a burglary at Pfizer made it clear to the drug company that they had ‘potent’ drug (Blech 2002). But this was – as in many cases – a result of an observation and not of scientific research. Only the follower drugs, such as Cialis or Nuviva who copied the prototype, are based on scientific research.

That means: if one or several trails find that a remedy is not more effective than a placebo this does not mean that the remedy is ineffective. It means that it is ineffective under the conditions of investigation, or at least not very often or not the way it was measured or not according to the therapeutic model.

Negative studies often result in the prohibition of a remedy. Or it is no longer paid by the national health insurance. But what does this help? In the case of mild drugs – as many herbal drugs – nobody has expected a big difference to the placebo in the first place. When they are not prescribed anymore, ‘stronger’ drugs, i. e., drugs with a higher incidence of side effects (and more expensive drugs) will be prescribed. This happened in Germany, when after a reform of the health system in 2004 all over-the-counter drugs, were not covered anymore by the national health system (Ring et al 2004). As a whole, the result is not better but worse for the patient (Ernst 2003b).

EBM is in a certain range of medical problems neither scientifically valuable, nor helpful for the patient, nor economically reasonable.

previous -- home -- content -- next