Neuroscience

The most common definition of Evidence-Based Medicine is from Dr. David Sackett:

"Evidence based medicine is the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research" (1996).

In order words, EBM integrates clinical experience and patient values with the best available research and aims to increase the use of high quality clinical research in clinical decision making.

(Szajewska, 2018)

Your literature search will be more successful if you first spend some time developing a research question and then revisiting and revising that question. 

The PICO Method

In order to help frame the clinical question in evidence-based medicine, PICO is a helpful mnemonic used to assist researchers develop and determine the most relevant and useful variables. 

A.) Read the clinical question

B.) Identify the PICO elements (see chart below)

C.) Restate the clinical question

Example

1. Read the clinical question
In ischemic stroke patients, how does neurological rehabilitation differ for those who received tissue plasminogen activator (tPA) versus those who did not?

2. Identify the PICO elements

3. Restate the clinical question

Among ischemic stroke patients does utilizing tissue plasminogen activator (tPA) versus not utilizing tissue plasminogen activator (tPA) affect rehabilitation with fewer neurological and physical deficits?

Once you have a PICO question, you can start your research, but be aware of the hierarchy of evidence, as this is a core principal of EBM.

EBM hierarchies rank study types based on the strength and precision of their research methods. Different hierarchies exist for different question types, and even experts may disagree on the exact rank of information in the evidence hierarchies. Still, most agree that current, well designed systematic reviews and meta-analyses are at the top of the pyramid, and that expert opinion and anecdotal experience are at the bottom.

(Szajewska, 2018)

Critical appraisal is the systematic evaluation of clinical research papers in order to establish:

1. Does this study address a clearly focused question?
2. Did the study use valid methods to address this question?
3. Are the valid results of this study important?
4. Are these valid, important results applicable to my patient or population?

If the answer to any of these questions is “no”, you can save yourself the trouble of reading the rest of the article. Keep searching!

This is ultimate goal of EBM: to integrate and apply the current best clinical evidence for the optimization of a specific patient.

In the application of the evidence obtained and vetted in the previous steps, the first question to ask is:

Can valid results be applied to this particular patient?

Once you have appraised a systematic review or primary study you need to decide whether or not it's findings can be applied to your specific patient. In doing so, you should take into account your patient's unique characteristics, circumstances, and personal preferences.

Questions to ask in clinical decision making:

Interventions (including systematic reviews of intervention studies and studies of risk/harm)

• Is my patient different from those described in the study so that the results of the study are not applicable?
• Is the treatment feasible in my practice setting?
• What would be the potential benefits and harms (i.e. side-effects) for my patient from this treatment?
• What are my patient's values and expectations for both the outcome I am trying to prevent and the treatment on offer?

Diagnostic tests

• Is the test available, affordable, accurate, and precise in this setting?
• Can I generate a clinically sensible estimate of my patient's pre-test probability?
• Will the resulting post-test probabilities affect my management and help my patient?

Prognosis

• Are the study patients similar to my patient?
• Will this evidence make a clinically important impact on my conclusions as to what to tell the patient?

The last step in the EBM protocol may appear the least complicated, but it is the most important. Subsequent assessment is an essential step in the healthcare process, as it is the step in which actual results and outcomes from therapies are observed, evaluated, and documented. This is an important step where results of previous work are shown and helps healthcare professionals gain new clinical experience and knowledge.

Centre for Evidence-Based Medicine (2009). Critical appraisal tools. Retrieved from https://www.cebm.net/2014/06/critical-appraisal/

Sackett, D. (1996). Evidence based medicine: what it is and what it isn't. BMJ (Clinical research ed.), 312(7023), 71–72. doi: 10.1136/bmj.312.7023.71

Szajewska, H. (2018). Evidence-based medicine and clinical research: both are needed, neither is perfect. Annals of Nutrition & Metabolism, 72 (suppl 3):13–23. doi:10.1159/000487375