[Why controlled studies may lead to misleading and unconfirmed therapeutic concepts--a critical view of evidence-based medicine].
The concept of evidence-based medicine has gathered widespread support during recent years. While this concept has clear merits in compiling and qualifying up-to-date information for clinical decisions, it should be viewed with caution as the sole valid knowledge source for clinical decision-making. The limitations of such an approach are particularly striking when reviewing two key developments in modern cardiology, fibrinolysis and acute percutaneous intervention in acute myocardial infarction. In both cases, early studies and meta-analyses showed no benefit for these therapeutic interventions over earlier treatment. Only after further refinement (mainly in dosage, time window, concomitant heparin therapy for fibrinolysis, and the introduction of stents and IIb/IIIa inhibitors for acute intervention) did these therapies become universally acknowledged. It is therefore crucial to understand that especially for physicians actively participating in the development of a clinical field clinical decisions cannot be exclusively based on published evidence. Another important problem to consider is the time gap between the emergence of new therapies and the publication and reception by the medical audience, in particular in rapidly evolving fields as cardiology. While it is clear that clinical decision-making must be backed by solid knowledge of the published evidence, in particular the specialist involved in-depth in the field may use not yet proven therapeutic concepts and measures to the patient's advantage.