[Systematic reviews in cardiology: approaches to evidence-based medicine and the Cochrane Collaboration].

The ever growing tide of results from great numbers of clinical studies clearly outweighs the abilities of the individual clinician to keep abreast of the actual state of scientific evidence and to apply it in his clinical decision-making in a timely and valid manner. Evidence-based medicine, with its central demand to link best individual clinical knowledge with best available external, scientific evidence to achieve optimal patient care, has clearly identified the urgent need for scientific techniques which allow the synthesis of scientific evidence, as collected in numerous singular studies, in an explicit, reproducible, and critically appraisable report format, and to update these reports regularly. The methods of Systematic Reviews, encompassing the techniques of meta-analysis, were developed for this purpose. They are explained and presented here in detail as they relate to the field of cardiology. Various problematic aspects have recently dominated cardiologists' discussion of meta-analyses. We point out that the techniques of Systematic Reviews hold promising solutions for many of them and that work on technical improvements is ongoing. The International Cochrane Collaboration is introduced as a global network of scientists and experts from varying fields of medicine with the aim of producing highest quality Systematic Reviews on a wide scope of topics. However, to date only few cardiologists have joined the rapidly rising numbers of Cochrane collaborators.