Wednesday, March 08, 2006

Evidence-Based Medicine - Science for a Change!

It may be surprising to learn that the gold standard of clinical guidelines - evidence-based medicine - is a recent concept. In the last decade, the idea that we must use hard data as the basis for medical decisions has taken root as our years of "that's the way it's done" tradition-based approaches are falling by the wayside.

The evidence-based approach took hold as our understanding that 'all evidence is not created equal' took hold and standardization of study design and weight came to be accepted. Studies are now subject to review to determine the "level" of weight the data should carry in assessing the conclusions and subsequent recommendations borne from that data. The highest level of evidence is "Level 1" evidence - these trials are considered the gold-standard and employ strict randomization and controls and are prospective - that is, looking forward.

Data gathered from studies that are retrospective, or less controlled, are weighted as less rigorous, thus not considered as highly as Level 1 evidence. These studies are still important though - they provide perspective and a different measure of findings. If you were to review the entire body of medical literature, most studies fall into the categories of Level 2 to 3 evidence since Level 1 data is more time consuming, costly and requires stricter control to take a study from start to finish.

Evidence-based medicine has taken hold in a wide range of specialties. Imagine my surprise though when my husband, Dr. Gil Wilshire, MD, FACOG, was invited to write an editorial in the journal, Age Management Medicine, on the topic of evidence-based approaches in anti-aging medicine. His editorial, The Evidence-Based Nature of Age Management Medicine, highlights how far we still must go to employ evidence-based medicine for our aging population.

The field of Anti-Aging Medicine, as perhaps no other, has been fraught with wild claims and unsupported assertions. In preparing to write this editorial, I randomly read through a sampling of various popular websites. As you can confirm for yourself, the “literature” is full of case studies (“N’s of one”), cross-species inferences, improper use of surrogate markers, and lack of proper control groups. I do not mean to disparage this entire field. By definition, the study of the medical issues of aging requires a long time to study! The testing of some of the most important currently contested hypotheses may potentially take generations to be done properly and effectively. The field of Age Management Medicine will present enormous challenges to the courageous investigators who choose to work in this field. For these reasons, the advent of this new, evidence-based journal represents a tremendous advancement for this specialty and for the advancement of human health in general.

His article is rich with information for any reader to develop their own critical analysis skills when reading a study. In it, you'll find information about common words that should be considered 'red flags,' common errors that appear in many studies, how to tease out conflicts-of-interest and some basic rules of thumb that will help you understand what you're seeing in a published study.



  1. Out of curiosity, what "level" was the WHI study?

  2. color me confused...LOL...I think your comment got attached to the wrong article - but if you're asking the level of fat intake for the WHI study - the goal was 20%, at year 1 intake was 24% and at year 6 it was a bit less than 28%.

  3. newbirth,
    I think that the level of evidence for the WHI study would rate no higher than a Level 2. You could also "rate" the conclusions of that study as barely Level 3! :-)

    I say that because the control group seemed to not be that well controlled and you could say the same for the intervention group. At best the data is "soft" and if anything did not produce the results the researchers claimed, as Regina pointed out in her blog.

    Hope that answered your question.

  4. Oh duh! Larry's right, the WHI study is Level 2 evidence...some of the conclusions, however, I'd consider Level 3. It ranks as Level 2 for a few reasons - things like the food recall instead of the researchers controlling what was eaten; the small number who actually were selected in the follow-ups which excluded some from the random selection process; self-reporting by the participants of medical issues they may have had.