Editor’s Corner: Practicing Based on Evidence

One of the NLA's missions is to move our educational efforts towards practicing based on best evidence. You will be seeing segments of Lipid Spin dedicated to this objective. There are many interesting aspects of lipidology addressed and displayed in a multi-disciplinary fashion in this edition of Lipid Spin. Thanks to Perry Weinstock, MD, as he assembled many contributors for each of us to learn from. There are many types of articles presented in this issue and there are many practical things to learn about. In particular I would like to highlight the articles by Spencer Kroll, MD, PhD, and Merle Myerson, MD, EdD.

The article by Dr. Kroll illustrates an important EBM concept and uses a great example of how to interpret and clinically use relative risk and absolute risk. As consumers of the literature we all need to be knowledgeable about these terms and what they mean and how best to use them. We should all be aware that relative risk can be used in studies that are analytic (control groups) where data is accrued in a prospective fashion. Understanding the magnitude of the relative risk and the confidence limits around the relative risk is important. The relative risk is helpful in contrasting outcomes (comparing the treatment arms) in clinical trials or in cohort studies that use cumulative incident data— the proportion of new cases of disease during a specific time period. Relative risk is a very useful concept because it focuses on the magnitude of the comparison of the groups. It is helpful in understanding associations and helps move our understanding towards causation.

As clinicians what is most important to us however is understanding the absolute risk for each of the groups being studied but most importantly focusing on what the absolute risk reduction is if there is a difference detected between the comparison groups. Understanding the magnitude of the difference and if it is clinically important is a must. We can quantify this by taking the absolute risk difference and then dividing this into one. That gives us the number needed to treat for benefit or, depending on the context, it gives us the number needed to harm. This is interpreted as the number of patients needed to prevent one outcome in a specified period of time.

The article by Dr. Myerson is a great illustration of finding evidence and using it to deal with a clinical scenario. Importantly, it points out where there are gaps in evidence, and that finding evidence and evaluating evidence is not by itself ever enough. We need to be able to find out if information available is valid, if it fits our particular patient’s clinical presentation and value system. In short, we need to integrate our decisions as this case illustrates. That is the art of clinical practice. Importantly, as clinicians, we often disagree regarding management when there are gaps in evidence available. We always need to be mindful of the clinical circumstance and the specifics of any given clinical situation. What about likelihood of compliance, for example, in this case with lifestyle management? When is medication indicated? How motivated is the patient in front of us? What other therapies is he or she using besides our counsel?

We are pleased to provide these articles and they are published here with the goal of generating thought, discussion and debate. That’s what is great about the NLA.