Once you have located relevant articles, you must appraise the information contained within the studies in order to determine whether 1) the results are valid and 2) do they apply to your patient/population. The following resources can assist you with the appraisal process.
The template below provides structure to the extraction of key pieces of information in order to appraise the literature:
The evidence to assess the validity of the information is found primarily in the introduction or methods section of the article. Does it address all the elements of your question, or only portions? This is also where investigators address any inherent bias in the study.
The methods section should allow you to find the publication type, a description of the patients included and excluded from the study, and the number of patients studied. The greater the similarity between your patient and the patients studied, the more likely the results apply to your patient.The greater the number of patients studied, the more likely the results of the study will be significant.
The results section of the study should provide numbers so you may make some simple calculations. The calculations will add to your conclusions about the validty of the results of the study.
The discussion may contain notes about the limitations of the study, interpretation of the results of the study, ideas about areas of future study.
Traditional ranking of research assumes that the higher the level of the research study (i.e. randomized control trial), the higher the validity of the evidence. However, other factors such as the level of evidence for sample size and internal and external validity must also be taken into account in order to determine whether research findings are relevant to a specific patient population. The table below provides a four-criteria level of evidence classification designed to assess the rigor of quantitative/outcomes studies:
Source: Deborah Lieberman, M. H. S. A., & Tickle-Degnen, L. (2002). EVIDENCE-BASED PRACTICE FORUM. May/June, Volume 56 Number 3
Now that you have appraised the evidence, continue on to Steps 4 & 5: Apply and Assess.