Answering a Clinical Question using an Evidence-Based Approach
The success of looking for the answer to our clinical questions depends heavily on our ability to find the current best evidence; a task that can be either quick and highly rewarding or time-consuming and frustrating. How we succeed is dependent on which information sources we use, and how skilled we are in interpreting and applying these sources.
Identify the type of sources that are most likely to answer your type of question:
1. Primary sources
2. Secondary sources
Using the EB approach (as described in the Users Guides to Medical Literature) we can critically appraise primary and secondary sources by asking three fundamental questions:
– Are the results of the study valid? (is the design of the study or systematic review acceptable)
– What are the results? (understanding basic statistics such as relative risk, odds ratios, sensitivity, specificity)
– Will the results help me in caring for my patients?
Once we find an answer to our clinical question we can then perform a clinical action. This clinical action is not only based on the current best available evidence but is also influenced by other factors such as patient preferences, and practice environment (see diagram below).
The Evidence-Based Approach in Family Medicine
The rapid growth of clinical research over the past 30 years has necessitated the development of a new and different approach to the practice of family medicine.
The “Evidence-Based“(EB) approach requires us to make conscientious, explicit and judicious use of the current best research evidence when making clinical decision for our patients. It also requires the integration of this best evidence with our clinical expertise and our patient’s unique values and circumstances (David Sackett).
A formal EB approach to practice is useful for several reasons:
• Our daily need for valid up-to-date information about diagnosis, prognosis, therapy and prevention (It is estimated that for every three patients we see in our clinic, we are faced with at least two clinical questions requiring best current evidence)
• Our inability to afford more than a few seconds per patient for finding and assimilating evidence to answer these questions or to set aside more than half an hour per week for general reading and study
• Inadequacy of traditional sources (textbooks) for keeping up-to-date with new evidence
Methodologies for formally practicing an EB approach have been developed by various institutions and medical experts. These methods are well described in numerous texts and articles. See the How-to Guides and Other resources listed on this page.
Clinical Questions
Good clinical questions serve as a good starting point. There are 2 types of clinical questions:
Background questions
– ask for general knowledge about a condition
– have a question root (how, what, why), a verb, and a disorder, test, treatment, or other aspect of health care
– eg. What can precipitate an acute exacerbation of congestive heart failure?
Foreground questions
– Ask for specific knowledge to inform clinical decisions or actions
– Have four essential components(PICO)
1 Patient and/or problem
2 Intervention (or exposure)
3 Comparison, if relevant
4 clinical Outcomes
Clinical questions usually arise around caring for our patients. The key is in selecting which questions to answer using an evidence-based approach.
– Which questions do you need to answer immediately using background knowledge vs. which questions do you have time to find the best current available evidence to answer?
– Which questions are most relevant to your knowledge needs?
– Which questions are most feasible to answer within the time you have available?
– Which question is most likely to recur in your practice?