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What on earth is evidence-based medicine?

Phil Zeltzman, DVM, Dipl. ACVS

It’s difficult to go to a professional meeting these days, without hearing the words “evidence-based medicine” every few minutes.

But what on earth is evidence-based medicine?

Turns out that not all evidence is of equal value. Let’s take a basic example. A published report of the successful surgical repair of XYZ is interesting information, but it’s just a case report.

A case series is stronger information, but we are still dealing with case reports. And a randomized, controlled, blinded study is even more powerful.

The number of patients presented in veterinary and human studies is a very interesting topic. In our field, it is not unusual to read reports about a few patients: five, 10, 100 or more if we’re lucky. In human medicine, for a variety of reasons, physicians commonly seem to report on thousands or tens of thousands of patients. Clearly, it’s a numbers game.

So there is a hierarchy of research results that we as practitioners should keep in mind whenever we hear or read about a new treatment or a new drug.

Some authors consider that there are nine levels of scientific information:

1. In vitro research, i.e. test tube experiments.
2. Animal research.
3. Ideal, editorials, opinions.
4. Single case report.
5. Case series.
6. Case controlled study.
7. Cohort study.
8. Randomized, controlled, blinded study.
9. Meta-analysis.

Meta-analysis is another recent buzz word. What is a meta-analysis? It’s a study that thoroughly examines several studies on a similar topic. It then combines and analyzes the results. When appropriate, a meta-analysis includes a critical appraisal of the randomized controlled trials chosen. So a meta-analysis is sort of the ultimate scientific study, and that’s why it’s at the top of the pyramid.

We should therefore strive to rely more on large studies and meta-analyses, and less on case reports and anecdotal information. As we move up the pyramid, there are fewer articles that qualify as “excellent information,” but their relevance and value increase dramatically.

Ultimately, the goal of evidence-based medicine is to use the best available evidence drawn from the most credible scientific literature to make the best clinical decisions possible in your practice.

Unfortunately, a meta-analysis is not available on every topic, every disease or every drug. So we need to go down a step or two, until we find the appropriate study. That’s acceptable, as long as we remember how much faith to put into it.

Dr. Phil Zeltzman is a mobile, board-certified surgeon in Allentown, PA. His website is DrPhilZeltzman.com. He is the co-author of “Walk a Hound, Lose a Pound: How You and Your Dog Can Lose Weight, Stay Fit, and Have Fun Together (Purdue University Press).”

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