Evidence and its impact on pharmacy practice: Don’t be “evidence-illiterate”

In last month’s editorial, we highlighted that patients deserve the full scope of pharmacist practice to improve outcomes. We also said that evidence, not outdated restrictive legislation and politics, should define this scope. Evidence is spoken about a lot and is a fundamental focus of CPJ. But what is evidence, anyway? And why is an understanding of the principles of evidence important? Evidence is important because health policy-makers and payers demand it to make decisions on how to distribute scarce health care resources. In fact, the concept of evidence-based medicine is a Canadian invention. Sackett et al. defined it as “the conscientious, explicit and judicious use of the current best evidence in making decisions about the care of individual patients.” Health care policy-makers have extended this concept into their own decision-making processes to improve quality of care and patient outcomes, to fund existing and novel therapies/services and to control expenditure growth in the health care system. So, what is evidence? Stated simply, evidence is a form of proof of whether something works or not. Of course, it’s not that simple. It’s not a simple dichotomy of “evidence” or “no evidence,” but rather a spectrum or a hierarchy (Figure 1). The highest levels of evidence allow us to definitively say that “drug x causes y outcome” or, in pharmacy practice, “a pharmacist doing x causes y outcome.” It’s the strength of the cause and effect relationship. The highest level of evidence is a synthesis conducted in a replicable way (called a systematic review) of available studies. As randomized controlled trials (RCTs) are least prone to error, systematic reviews of high-quality RCTs with similar results would be considered strong evidence of an impact. There may be exceptions to this, depending on what questions are being asked. Systematic reviews may also identify RCTs with conflicting results (possibly due to different designs), which can further reduce the strength of evidence. While it is beyond the scope of this editorial to go into the detailed methods of research design (though we will in future articles on this topic), suffice it to say that RCTs are what get new drugs approved, and should be what gets funding for new pharmacy services. A good example of a large systematic review of pharmacy practice interventions was published by Santschi et al. and summarized in CPJ. In this review, the authors reported on 39 randomized trials (involving 14,224 patients) of pharmacist care for hypertension. They demonstrated an average blood pressure reduction of 7.6/3.9 mmHg, a compelling finding that should be implemented. Indeed, evidence is the “high road” towards a full scope of pharmacy practice. So why is a discussion on the principles of evidence important? Because many pharmacists, pharmacy organizations and policymakers are evidence-illiterate. And that hurts us as a profession, and, by extension, does not serve our patients and society well. When pharmacists don’t understand evidence, they promote things for which the evidence is weak or non-existent, e.g., diets, supplements, homeopathy, etc. They also do things Figure 1 The spectrum of evidence ChiRaNJeeV SaNyaL, BPhaRm, mSC, PhD;