Why don’t physicians follow evidence-based guidelines more often?

Many researchers complain that physicians often use treatments with little evidence to base these decisions. From off-label prescribing, to unstudied surgical procedures, physicians are often painted as cavalier practitioners who don’t read studies. For instance, Austin Frakt at Incidental Economist writes:

The British Medical Journal sifted through the evidence for thousands of medical treatments to assess which are beneficial and which aren’t. According to the analysis, there is evidence of some benefit for just over 40 percent of them. Only 3 percent are ineffective or harmful; a further 6 percent are unlikely to be helpful. But a whopping 50 percent are of unknown effectiveness. We haven’t done the studies.

A natural question to ask is ‘why isn’t the share of treatments without evidence 0% rather than 50%?’

However, a more balanced view is needed. It is unrealistic to think that 100% of treatments will be supported by Phase III clinical trials. There are a number of barriers for physicians to always follow evidence-based guidelines.

First, producing evidence is costly. The key problem with the Frakt article is that it only examines the benefits of producing evidence, not the cost. Bringing a drug to market costs over $1 billion. The typical Phase III trial cost $19 million. On a per patient basis, these trials cost $41,117 per patient; this is about 70% of annual earnings for a typical American. In short, the level of evidence physicians seek does not come cheap.

Second is that these clinical guidelines only incorporate information for the average patient whereas physicians must tailor treatments to specific patient needs. For instance, if treatment A is identified as optimal for treating a disease, but the patient is allergic to treatment A, clearly a physician must use their judgement to find an alternative treatment. Further, if a physicians knows that a patient won’t be adherent to the recommended medication, they may recommend alternative treatments. These are simple examples, but physicians have patient-specific knowledge that helps them decide whether a treatment is the right one.

Third, this analysis ignores patient preferences. It could be the case that there is Treatment A has strong evidence of a moderately positive health impact (perhaps from a Phase 3 trial). However, Treatment B may have very limited evidence but where evidence exists the treatment worked very well. For instance, anecdotal cases may give patients hope of a better outcome for Treatment B but no trials may have been conducted for that specific disease. In some cases, patients may prefer a treatment with a wide distribution of potential outcomes compared to one with evidence that produces only moderate benefits. Some may claims that these patients are making the “wrong” decision but an economist’s point of view is typically De gustibus non est disputandum (“In matters of taste, there can be no disputes”). Further, these guidelines often focus only on health outcomes and do not take into account mode of administration or other factors than can also affect patient’s quality of life.

Fourth, reviewing the academic literature is costly as well. While one would hope that physicians would be up to date on the latest treatments, this process is costly. In the future, information technology may help make best practice guidelines more accessible to physicians.

As a researcher, I am certainly in favor of more research to insure that each patient gets the right treatment at the right time. Decreasing the “50%” figure at the top of the post is an important objective. At the same time, one must recognize and at no point will 100% of medicine be fully evidence based…ad that may be a good thing.