Today Orac provided a useful perspective on CPGs and evidence based medicine (EBM), centering his comments around a paper in PLOS Medicine which on the surface could be construed as diminishing the value of EBM. But that interpretation, though likely to be trumpeted by the popular media and the alties, is not a fair rendering of what the paper actually said, as Orac went to considerable length to explain. The paper was not critical of EBM. What it did do is question the ability of CPGs to help clinicians practice EBM. The authors evaluated randomized controlled trials (RCTs) on which guidelines were based and found a disturbingly low number (about a third) that met two criteria: applicability to the patient populations targeted in the guidelines and reporting of “hard” clinical outcomes. The study may not be generalizable because of its narrow focus on a limited number of guideline recommendations. The authors were circumspect:
In conclusion, our finding that less than one-third of treatment recommendations (and less than half of those citing RCTs in support of the advocated treatment) were based on high-quality evidence in national evidence-based guidelines for common conditions should sound a note of caution to consumers of clinical practice guidelines who assume that the sobriquet “evidence based” means that all recommendations contained therein are derived from high-quality evidence.
For me this paper is a reminder that slavish adherence to CPGs is not the same thing as practicing EBM although it is popularly assumed to be so. The true steps of EBM are rigorous and time consuming as I have outlined before. Here I discussed the general steps of EBM and gave some case examples. In a more recent post I expanded on the first step of EBM (formulating a focused clinical question to be translated into search terms) by introducing the PICO acronym. The P in PICO stands for population and refers to the need to define the specific patient population that corresponds to your patient, and specifying the relevant characteristics in the focused clinical question and the search terms. That addresses one of the problems, cited by the authors of the paper, inherent in the use of CPGs by helping ensure that the evidence applied to the clinical problem at hand matches the attributes of the patient.
Once the search is done and the studies are collected there remains the important step of critical appraisal, an additional check point for the quality and external validity (applicability to your patient) of the evidence.
Much of what is said to be EBM is not EBM at all. The true practice of EBM is onerous. In many situations clinicians lack the necessary time to practice pure EBM. Although the use of guidelines is not a valid substitute for EBM guidelines can be helpful to the time strapped physician when viewed with an appropriately critical eye.