Evidence-Based Medicine Is an Imperfect Science

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Basing your health decisions on scientific evidence—a practice known as evidence-based medicine (EBM)—is generally a wise approach, but there are some controversies you should be aware of as an informed healthcare consumer.

Clinical trials are scientific experiments designed to look for evidence that a tested treatment will work. EBM, determined by the outcomes of clinical trials, should be an objective decision-making tool to help patients and their doctors make treatment decisions.

But evidence-based results may not always be as clear-cut as they seem.

How Can Medicine Based on Scientific Evidence Be Controversial?

Evidence-based medicine attracts some controversy over its objectivity, accuracy, and application. Some people, therefore, question whether it should be used as the basis for treatment decision-making.

The debates over evidence-based medicine stem from three main arguments:

  1. The evidence is gathered using groups of people, not individuals.
  2. Not all patients have the same set of values.
  3. There may be built-in biases in the way the experiments are designed, which may serve a profit motive.

Let's explore these points one at a time.

1. the Evidence Is Developed Based on Group Results, and Not Individual Results

Clinical trials focus on a group of people who have similar characteristics. But there are some potential problems with this approach.

  • The results may not translate to different populations. Clinical trials are often criticized for focusing mainly on people who are Caucasian and male, for example, and the results may not apply to women or other races. Age is another factor when applying clinical trial results to different populations.
  • Most trials fail for some people. Even if a treatment is, say, 90% effective, that means it's ineffective for 10% of people. And there might be a treatment out there that is more effective. 
  • The study may not have been large enough or long enough. Results and conclusions drawn from a group of 5,000 should be more accurate than if only 200 people participated in the trial, for example. A trial that lasted two years might be considered more accurate than one that lasted only six months.

2. Not All Patients Have the Same Set of Values

Evidence-based medicine is based on science. But when human beings need to make decisions about their treatment, they may consider the evidence in different ways based on their values.

For example, a woman diagnosed with cancer may not choose the evidence-based approach to her treatment if she's pregnant and the treatment will harm her fetus.

Evidence-based medicine makes no room for value judgments. Most medical professionals realize that a patient's values must be taken into account when treatment decisions are made, even though they are not accounted for in EBM.

3. There May Be Built-In Biases in the Way the Experiments Are Designed

Not surprisingly, this aspect of evidence-based outcomes creates more controversy than the others. Critics may cite the following arguments:

  • Studies often have a conflict of interest. Until the past few years, the results of clinical trials and experiments might be published in medical journals regardless of who sponsored them. This meant that a pharmaceutical company could publish the results of its own study showing its drug was the best drug for a particular ailment. Many medical journals have begun a crackdown on the authors of studies, informing them that they must make full disclosures about funding and conflicts of interest. However, some people believe this only encouraged companies with profit motives to look for more creative ways to prop up their skewed research.
  • Unfavorable studies and results may not get published. People who conduct studies and publish journal articles about them are under no obligation to reveal study results that might have been more negative to their businesses. They may only showcase their most positive outcomes.
  • Complementary, alternative and integrative medicine isn't well studied. Because therapies like herbs and supplements, yoga, massage, and acupuncture tend to cost much less than pharmaceutical drugs, there's little incentive for profit-driven groups to study them. And because those studies are not undertaken, there is little literature to support the use of complementary, alternative, or integrative therapies, even when they may be effective.

How Should Evidence-Based Medicine Be Used?

Many medical professionals will tell you that medicine is as much art as it is science. While much of evidence-based medicine is considered a gold-standard in treatment approaches, keeping the "art" aspect in mind is as good an approach as you and your doctor consider treatments.

Look at journal articles, make sure the information you have found is up-to-date and discuss the possibilities with your doctor. Look for evidence based on studying groups of people similar to you. Understand the possible pluses and minuses of any medical study and the evidence it has produced. And be sure to stay true to your values and beliefs.

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