Principles of Critical Appraisal
Why Critical Appraisal?
Why indeed?
Clinical medicine is an applied science. While most of us are not trained in the rigors of doing research, we must be able to understand and apply the research of others to our work. Critical appraisal of research a little like art appreciation or literary criticism - it requires understanding some context, understanding the tools and techniques, and evaluating whether the creators got their message across correctly.
We can let others do this critical appraisal for us. The publishers of textbooks, study guides and review journals succeed based on this idea. However, we need to know the basics of how to do it for ourselves, so that we can judge how well these other information sources critically appraise the information.
Six Basic Elements of Critical Appraisal
Assess the RESEARCH QUESTION
Why are the researchers doing this study?
identify the PICO question this study addresses - this is not always straightforward.
HINT - look at the last sentence in the introduction/background section.
P - patients/population
I - intervention/exposure/test of interest
C - comparison/reference standard
O - outcome/diagnosis
for more help with PICO questions, see Asking Focused Questions
Assess the STUDY DESIGN
How did the researchers decide to answer their question?
Assess the VALIDITY
Can we trust the results we get to be true and unbiased about the population studied?
Assess the RESULTS
What types of outcomes were studied, were there significant findings, and how significant were they?
Assess the APPLICABILITY
Can we use this evidence to treat out patients? Do the findings apply to our patients?
Decide on the CLINICAL BOTTOM LINE
If it's not valid, you should not use it.
It it's only applicable to some of your patients, or under select circumstances, then note this.
If you need to see other literature confirming this result before you change your practice, that's ok too.
Notes:
A quick review of basic critical appraisal terms, statistics and concepts: EBM Toolbox Glossary
We should always be able to cite the article appropriately so that we can refer to it. First author, journal, issue and page number are usually sufficient.
Additional Ways to Understand Critical Appraisal
The EQUATOR Network catalogues guidelines written for authors and editors to ensure that all useful information is presented in a journal article. These can be useful as checklists for critically appraising articles also.
Therapy Studies: CONSORT
Systematic Reviews: PRISMA
Cohort/Case-Control Studies: STROBE
Diagnostic Test Studies: STARD