Once you have found the most current evidence, the next step in the EBDM process is to understand what you have and its relevance to your patient and PICO question. One resource available to critically appraise papers consists of a worksheet with structured series of questions that help you determine the strengths and weaknesses of how a study was conducted and how useful and applicable the evidence is to the specific patient problem or question being asked. 1
Key Questions in Appraising the Scientific Literature
In order to become more proficient in judging the evidence, there are appraisal guides to ain in the critical analysis process:
Several online and print resources provide questions that can be used for reviewing the validity of other types of studies, such as those related to diagnosis, prognosis and harm/etiology as well as studies related to decision analysis, practice guidelines, economic analysis, and qualitative research.
The structured series of questions found in a checklist provide a guide in appraising the evidence. Once you have determined that the results are valid (the first key question), the next step is to determine if the results, potential benefits (or harms) are important. Sackett et al. identify the clinically useful measures for each type of study.6
For example, in determining the magnitude of therapy results we would expect articles report the control event rate (CER), the experimental event rate (EER), the absolute and relative risk reduction (ARR or RRR) and numbers needed to treat (NNT).
NNT tells us the number of patients (surfaces, periodontal pockets) that would need to be treated with the experimental treatment or intervention to achieve one additional patient (surfaces, periodontal pockets) who has a favorable response.
For diagnostic studies, the sensitivity, specificity and likelihood ratio should be reported.