Step 4 in evidence-based practice is about applying research evidence to the individual patient and clinical decision making. As described by Chang et al., study participants and real world patients are likely to differ by degree, rather than grossly, in their response to treatment. Individualizing treatment decisions involves estimation of the balance of risks and benefits, combined with a consideration of patient values. The number needed to treat (NNT) is the number of patients that need to be treated to prevent one additional adverse event, and it is the inverse of the absolute risk reduction. The number need to harm (NNH), in contrast, is the number of patients treated who would be expected to experience one adverse event. NNT and NNH illustrated the balance between benefits and risks of a given intervention; in oncology, this is particularly relevant with to screening, which may result in harms from follow up of false positives, and treatment, which often produces dose-dependent toxicity.
Levels of decision making:
Dr. Leon Gordis (Johns Hopkins University) described the following levels of decision making on applying evidence to a particular patient.
Resources for EBM as shared decision making:
Levels of evidence:
The National Cancer Institute defines levels of evidence as "a ranking system used to describe the strength of the results measured in a clinical trial or research study. (such as a case report for an individual patient or a double-blinded randomized controlled trial) and the endpoints measured (such as survival or quality of life) affect the strength of the evidence."
.
As you move up the pyramid, however, fewer studies are available; it is important to recognize that high levels of evidence may not exist for your clinical question. If this is the case, you will need to move down the pyramid if your quest for resources at the top of the pyramid is unsuccessful.
Resources for level of evidence:
References:
