Opinion, Evidence, and Consensus Statements

In the future, I'll write more about this subject, since the distinction between expert opinion and clinical experience seems to cause unending confusion to people who write and talk about EBM.

For now, though, I want to write about the second recent event that caused me to decide to blog on evidence and medicine. I caught a snippet on NPR's Science Friday where they were talking about concussions in athletes and heard the following: "And take a very careful step-wise return not just to the playing of the sport, but also to even, you know, text messaging and doing things intellectually that can be harmful to their brains while they're still recovering from a concussion." www.npr.org/templates/story/story.php?storyId=120174333

I was startled to hear that an expert thought that someone should not be texting after a concussion (it turns out this is referred to as "cognitive rest"), and I had a hard time believing there was any evidence for it. And though I have no expertise in concussion management, the idea sounded somewhat contrived or even goofy to me.

It turns out that this mainly comes from consensus guidelines for the management of concussion (PMID 19433429) where, if they have any evidence to back this up, I couldn't find it. I certainly didn't find any published studies showing that cognitive rest improves outcomes after a concussion. If anyone reading this knows of such evidence, I'd be interested to see it.

To make recommendations, experts always need to interpret what evidence there is (expert opinion), and in the absence of high or moderate quality evidence about cognitive rest, the consensus panel presumably had to make their best guess for management. This particular recommendation seems a bit odd in that it has potentially high burdens on the injured athlete (don't read; don't text) in the absence of good evidence, and rest is not always such a good idea after a physical injury -- bed rest for low back pain and immobilization for an injured shoulder are both clearly a bad idea. But ultimately doctors need to either recommend cognitive rest or not recommend it and if some people think it's a good idea an expert recommendation is required.

However, a certain degree of humility would seem to be required when transmitting a recommendation grounded in such low quality evidence. Perhaps this is not such an instance, and I am just missing the better evidence, but it would certainly be common to hear expert panels and individual doctors make forceful pronouncements based on little or no foundation. If there really is nothing much to support this, perhaps the experts describing the recommendation (both in the guideline and on the radio) might have said, "Well, we think cognitive rest is a good idea, but we don't really know. In fact, for all we know, it might do more harm than good."

So, while I'll write more about expert opinion and clinical experience down the road, this episode of seeing yet another consensus guideline treated as gospel was an added push to create this blog.

Comments

[storkdok]

Now I feel inadequate. I've never heard the term "cognitive rest". Sounds rather silly to me. Could you really hurt your brain more by thinking? If this is recommended, where do you draw the line on how much thinking/work is acceptable?

[Marilyn Mann]

Hi David, here is the comment from my friend, Joseph Sonnabend, M.D.

What are the criteria for elevating someone to the status of expert? Here is a quotation from David Sackett:

"The practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research. By individual clinical expertise we mean the proficiency and judgment that individual clinicians acquire through clinical experience and clinical practice".

This is a pretty loose description of what constitutes "clinical expertise" - but whatever it is, it most certainly includes a requirement for experience.... Read More

Unfortunately those clinicians with the greatest experience are busy physicians without academic affiliations and their opinions are never sought and usually dismissed when offered. The "experts" are usually academic physicians and in some cases are not those with the greatest clinical experience. At least this is the case in a field with which I'm familiar - HIV medicine. I wonder how many patients some "experts" who sit on guidelines committees actually see, considering the time spent on non clinical activities such as teaching and lecturing - often on industry sponsored educational activities.

Busy clinicians seeing patients day after day are admittedly often not trained to make systematic and formal observations. Yet they do constitute an invaluable resource whose opinions are often disparaged by their academic colleagues.

We should find ways to tap into this great resource. I have been both an academic physician and a busy provider, - though not at the same time. My views of HIV disease - one which other physicians in full time practice have shared, is quite at odds in some respects with those of the "experts" whose opinions provide support for treatment recommendations.

Finding ways to usefully tap into the day expertise accumulated over many years by busy physicians in full time practice may not be so straightforward. At least in the field of HIV medicine we may obtain a more realistic understanding of the natural history of HIV disease with it's tremendous variability from person to person. One consequence will be the understanding that treatment l needs to be individualized to take into account, among other differences, the vast differences in the rates of disease progression that can be seen between individuals. Instead we have a one-size-fits-all approach foisted on us by "experts", an approach that sometimes seems to be more in line with the marketing needs of industry than the needs of our patients.

Here is another quote from David Sackett:

"Good doctors use both individual clinical expertise and the best available external evidence, and neither alone is enough. Without clinical expertise, practice risks becoming tyrannised by evidence, for even excellent external evidence may be inapplicable to or inappropriate for an individual patient. Without current best evidence, practice risks becoming rapidly out of date, to the detriment of patients".

The best available external evidence often provides general guidance. Individual clinical expertise will apply this to particular patients, taking into account many factors, not least of which, in the case of HIV medicine, is an individual patient’s rate of disease progression.

The challenge is to find ways to tap into the clinical expertise acquired from years of experience by busy practitioners. To be useful, this will require a clearer definition of "clinical expertise". Just the length of experience is almost surely not sufficient.

[Marilyn Mann]

Correction -- in the comment from Dr. Sonnabend, the third paragraph should read as follows:

This is a pretty loose description of what constitutes "clinical expertise" - but whatever it is, it most certainly includes a requirement for experience.