Using evidence in the practice of medicine requires minding three areas:
- the best available evidence,
- the clinical scenario and
- the patient’s values.
There are four steps to carry out this process.
- ASK a clinical question (PICO). During the care of your patients, you’ll come across something to which you don’t know the answer. This uncertainty is the start of your EBM journey. If the answer is well established can easily be found in a textbook, it’s considered background information. If the answer is being newly discovered and found in the literature, it’s considered foreground information.You’ll need to shape that question into one which can be fit to the literature. This most commonly used format is PICO.
- P = patient – describe your patient, demographics, co-morbidities, etc so you can find as good a match of patients in the literature
- I = intervention – what is the intervention about which you have a question? Are wondering about the effectiveness of a new drug, the potential harm of continued exposure to a toxin or the usefulness of a new blood test in diagnosing your patient.
- C = comparison – you need to compare your intervention against something. Usually, this will be against what a placebo drug (for new treatments), unexposed people (for patients exposed to a toxin) or a gold standard test (for new diagnostic tests).
- O = outcome – what is the outcome you’re looking at? Will the patient’s disease improve? Will the exposure cause cancer or death? Or will the new blood test have a high sensitivity in picking up the disease?
- ACQUIRE the evidence. Next, you need to acquire the evidence. This is easier said than done. If you put the question into a search engine you may get thousands of irrelevant hits. Even specialized search engines such as PubMed or Google Scholar can lead to unrelated articles. Using the proper search terms and tools helps narrow down the results.
- APPRAISE the evidence. Once you have the article, you need to read it and appraise it’s validity. Is this paper done well? Can you trust the results? Can you use the results? The famous Users Guide to the Medical Literature (from JAMA in the 1990’s by Guyatt and Leavitt) provides a framework for how to evaluate papers based on the type of question.
We’ll look at these in each of the small groups.
- APPLY the evidence to your patient. If you’ve determined the paper is usable, then you need to apply it to your patient. Part of this should include an audit of how well that evidence worked.
How to read papers
- Read the ABSTRACT to get a general idea of the direction in which we’re going.
- Read and interpret all the TABLES and FIGURES, using the captions if needed.
- Now you can go and read the METHODS and RESULTS. Armed with the info you learned in Step 2, this should go much more quickly.
- Now come up with your own interpretation results of the study.
- Now you can read the INTRODUCTION and DISCUSSION. Does this match with what you came up with in the step above?
You can practice with NEJM’s Coffee and Pancreatic Cancer (1981) or just use this to follow along with the videos.
Good luck and happy appraising.