Evolution of EBM. Part 2: Systematic summaries of evidence as a milestone in the clinical decision-making process

Roman Jaeschke, MD: The next question concerns your views on the role of systematic reviews and meta-analyses in the whole evolution of evidence-based medicine (EBM) and their place in this decision-making process.

Gordon Guyatt, MD: One of the key principles we believe is that to make the right decisions we need systematic summaries of the best evidence. Historically, there is a lot of examples when people have not had systematic summaries of how badly wrong they could go. If you go back 25 years and look at expert recommendations in cardiovascular disease, for example, when thrombolysis first came around, you had experts saying yes for everybody, no for anybody. A decade between the time that the definitive evidence was available and the experts finally got together.

Another example is that we frequently used lidocaine in patients with acute coronary disease. When I was in training we gave it to everybody. As it turns out, there were randomized trials at the time I was giving it showing no benefit, but nobody was paying too much attention.

Experts are still going wrong but nowhere near as badly because now we have systematic summaries of evidence that are very prominent. Now there are literally thousands of systematic reviews and meta-analyses. Appropriate guidelines and appropriate evidence sources like McMaster Textbook of Internal Medicine or UpToDate say we always need systematic summaries, ideally in systematic reviews and meta-analyses, to inform our decisions.