Tuesday, January 18, 2011

Why the profession's adherence to evidence based medicine can never be measured

In today's conversation about health care reform evidence based medicine (sometimes referred to by popular synonyms such as “best practice” or “what works versus what doesn't work”) is a hot topic. Politicians and policy experts believe doctors' adherence to this ideal is poor. Some advocate for policy measures designed to improve on this situation. Such thinking is based on the faulty premise that adherence to EBM can be measured. Experts cite guideline usage or, worse yet, performance metrics as measurable processes to assess EBM adherence.

Such thinking is profoundly simplistic and naïve.

EBM adherence cannot be measured. Why? The answer is to be found in the definition of EBM as put forth by its founders. They wrote it here. David Sackett said it again here. Read and listen carefully. EBM has three key elements. If any of these three is missing, it's not EBM:

The individual patient
The patient's unique attributes, biological, social, psychological. This includes attitudes, preferences and external circumstances.

Individual clinical expertise
That means the expertise, in diagnosis and treatment, of the individual doc who's delivering the care.

The best external evidence

The first two elements are not measurable. The third element seems measurable in concept but in actual practice is inscrutably hard. Sometimes it's elusive. Guidelines and performance measures are not valid surrogates for best external evidence.

It's way, way more complicated.

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