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The Hidden Secrets of Evidence


I have a fear.'  My fear is that the public has an unrealistic view of medicine and the science behind it. This is partially due to practitioner behavior (I count myself in this group) and the media.'  Are we cultivating a society that won't believe anything we say or conversely think everything they read is true and everything is possible? And how have we contributed to this mess?

Many health care professionals forget that the original intent of evidence-based medicine was to use medical science, in conjunction with practitioner judgment and patient values to make treatment decisions.'  Too often a tool of evidence-based medicine (a clinical guideline) has become a blunt instrument, indiscriminately applied.'  I know I have a bias because I practice geriatrics, where patients become more and more unique the older they get.'  As John Sloan says, caring for the frail elderly is an 'evidence-free zone.''  Thankfully, more and more organizations (the VA is a prime example) are realizing that one size does not fit all and a self-correction is currently happening (see this article by Eddy et al), and professional associations that often create guidelines are backing off their earlier targets.'

One of the most troubling aspects of evidence-based medicine is can we trust the evidence?'  Now, I can cite the evidence like the most seasoned academic, and I know it should all be taken with the proverbial grain of salt.'  What Archie Cochrane, the father of evidence-based medicine popularized is that we need to understand:

  1. Can it work (efficacy, often determined by a clinical trial or study
  2. Does it work (effectiveness, in the real world with real people outside of a research setting)
  3. Is it worth it? (remembering that resources are finite)

Let's look at each in turn.'

For #1, can it work, Dr John Ioannidis and his research group have cast a light on how limited our evidence really is, pointing out that a quarter of highly cited studies are never repeated; 16% when replicated, have weaker effects than the original research; and 16% of replications contradict earlier evidence.'  This means we have reason to doubt over half of all published findings.'

The second, does it work, is also challenging.'  Most medications are tested in a select group of people who do not have kidney or liver problems, don't have many other illnesses other than the one in question and have a lot of support to take the medication and are followed regularly by those conducting the research.'  I know this first hand, I worked on clinical drug trials for a couple of years.'  This is far different than the real world of practice, where people are complicated, staff don't see you back in a few days to see if you are having any side effects, and about half of people don't fill prescriptions.

And the third question, is it worth it, has recently been addressed by Jarvinen and colleagues in an article about preventive medications.'  They remind us how much the picture changes when we move from efficacy studies (1) to effectiveness (2) to cost-effectiveness (3). One of their calculations reveals that by administering medications to prevent osteoporosis to 1.86 million people over the age of 50 would result in 343 fewer fractures.'  If their calculations hold up, this is an incredibly sobering message for preventive medication.So where do we go from here?'  I propose that clinicians:

  1. always couch evidence as 'our current understanding' to remind patients that medical science is always evolving and that it may not apply to them as an individual,
  2. include patient values and their clinical judgment when considering the evidence (i.e. 'evidence informed medicine'),
  3. consider the big picture of societal cost,
  4. work to find ways to explain risks and benefits of preventive medication (and include potential harms in shared decision making for all medications

I'll be glad if we can keep all of these thoughts in the day light. The evidence is part of the picture, and we do the public a disservice when we present emerging findings as fact and fail to think about all the possibilities for individuals and society.' '  I'm also not sure if the public is ready to hear that medicine really is not ALL science.

More Blog Posts by Connie Davis

author bio

Connie Davis MN, ARNP is a geriatric nurse practitioner, health care consultant and William Ziff Fellow at the Center for Advancing Health. This blog was originally posted on Connie’s website where she blogs about improving the patient experience. You can read Connie’s blogs and subscribe to her RSS feed here and follow her on twitter at @ConnieLDavis.

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Evidence-Based Medicine   Connie Davis   Make Good Treatment Decisions   Inside Healthcare  

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