Tarnished Gold Chapter 2: Populations are not people

Populations are not people

First off the authors state that decisions sciences do not relate to EBM. They feel decisions are personal and statistical information is not important. They give the example of organ transplantation. Unfortunately, they skip an important step in their argument. Namely, that to know an organ transplant will be of benefit is based upon studies proving that they prolong life and these are based on statistical information.

They argue that EBM is based on a statistical blunder: the ecological fallacy.¬† There is some merit to this argument. The average finding applies to the average patient. What if your patient isn’t average. There are a couple of options. First, you could calculate your patient’s estimate of benefit (or risk) using the results from the study like I demonstrate in this video.¬† Almost every study report will include a confidence interval around the point estimate of benefit (or harm). The point estimate is the best guess about the findings of the study but there is uncertainty and the confidence interval helps quantify that uncertainty. You could use the upper and lower bounds of the confidence interval and decide if it includes a clinically important benefit. Finally, you could look for a subgroup analysis (yes I recognize the limitations of this) of a group of patients similar to yours. Despite all this, science is based on inference. We can never measure the effect of an intervention in all people. We often use inductive and deductive reasoning in science.

The authors spent several pages discussing pattern recognition in medicine and that EBM doesn’t help this. This is both true and false. It is true in that we are taught how certain things look and there will never be a study related to that. We have numerous studies though of how good elements of the history and PE are for diagnosing disease. Many of these are pattern recognition. We learn that peripheral edema, orthopnea, PND, and DOE are most likely congestive heart failure. That is pattern recognition but there is also a study that examines how good each of these components is to increasing or decreasing the probability of CHF. Thus, pattern recognition is informed by EBM.

There are more claims to be refuted in this chapter but these are the main ones worth refuting.


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