Guidelines are wonderful. Guidelines are dangerous.

Over the past decade, I have thought often about the benefits and the problems of clinical guidelines.

The first concept that attracted my attention was reading about conflicting guidelines. Given the same data, different guideline committees would have significantly different recommendations. At the least, this problem raises questions about guideline validity. It makes clear that committee perspective could influence recommendations. Guideline recommendations sometimes are clear and demonstrably evidence based, but too often recommendations reflect the committee’s view of the problem.

The pharyngitis guidelines represent a perfect example. Matthys wrote a very important paper in 2007: Differences among international pharyngitis guidelines: not just academic. The paper’s last paragraph defines part of the problem:

National guidelines on acute sore throat promote different clinical approaches, recommend different treatments, and cite different evidence. There is no evidence that regional variation is appropriate. Introduction of an explicit guideline development method for both European and North American guidelines may lead to more uniformity in the diagnosis and management of acute sore throat.

But this article does not even reflect what I consider the biggest problem: diagnostic criteria.

When we consider the pharyngitis guidelines (or the sinusitis guidelines for example), we read how to consider the patient, but though sometimes the guideline mentions exclusion criteria, the guideline statements rarely do. Let me emphasize this point in my understanding of pharyngitis.

When considering acute pharyngitis, we should define the red flags that make the guideline not useful. The guidelines assume acute pharyngitis, but do they define how long a patient has had the sore throat with a longer duration being an exclusion? Do they define clues that the patient does not have a routine pharyngitis: unilateral neck swelling, rigors, worsening symptoms? Usually, guideline statements assume that we have enough knowledge to make a diagnosis and that making that diagnosis — routine pharyngitis — is not a problem. Yet when I hear about mismanaged sore throats, generally physicians have “followed a guideline.” The common mistake is not recognizing that the patient’s presentation makes the guideline not relevant!

The problem here is a long tail problem. As physicians, we strive to know when a patient’s presentation is not routine. Our challenge comes from knowing when we should switch from system 1 (or automatic) thinking to system 2 (deliberate) thinking. What clues must we consider prior to using a guideline?

Too often we see patients with diagnostic labels and “perfect” treatment for those labels — e.g., CHF or COPD. But when we consider the patient more carefully we see that the patient does not carry to correct diagnosis. The treatment (guideline directed) is wrong because the diagnosis is wrong.

Perhaps guidelines should start with a very careful inclusion definition. So for acute pharyngitis perhaps we would require short duration (at most 3 to 5 days), and no red flag symptoms. For systolic dysfunction, we might define an inclusion ejection fraction. For COPD we should require full PFTs (to define obstruction and exclude restrictive lung disease).

I submit this is not a trivial problem. Guidelines become recipes, but recipes do not work with the wrong ingredients. Guidelines should not suppress the physician’s thought process. Perhaps a great guideline would define the warning signs (or “red flags”) that should induce more careful thinking. As an academic perhaps I worry too often about zebras, but then working at a community hospital and a VA hospital, I sure seem to see them.

I often say the diagnosis is job #1. We need our guidelines to clearly define the relevant patients for that guideline. The guideline should direct us to return to the diagnostic process when the patient’s problem representation does not fit the illness script that the guideline defines.

Robert Centor is an internal medicine physician who blogs at DB’s Medical Rants.