Evidence-Based Medicine and Radiology

As I was exploring educational topics relating to radiology, I came across an interesting concept that I hadn’t been exposed to before. It was the idea of applying evidence-based practice to radiology. My initial reaction was: oh it’s just the application of research to everyday practice. And essentially that’s what it entails. But what does that mean specifically and for radiologists?

In order to understand evidence-based radiology (EBR), one has to first understand evidence-based medicine (EBM). Essentially, people have been practicing EBM for generations but it wasn’t until the 1990’s that Dr. Gordon Guyatt and his group from McMaster University formally recognized and defined the approach. EBM is the systematic method of finding, critically appraising and applying up-to-date research to make clinical and policy decisions. At the end of the day, it is another tool we can use to guide our daily practice and potentially health care policies.

There are two important differences between EBM and conventional practice. First is the rigorousness of EBM. Good controlled trials nowadays use explicit criteria and standardized methods in obtaining and assessing the strength of their results. For years the scientific community has adhered to these values so that methods and results are transparent and reproducible. The second advantage of EBM is that it enables practitioners to develop their own strategies when faced with the “grey area of medicine”. It gives them the knowledge and tools to assess the available literature and make choices based on solid reasoning.

Broadly speaking, EBM is important any time one experiences a personal “knowledge gap”. While traditionally in these situations one would turn to their mentors and just imitate their approach, with EBM one can now critically assess these decisions with the existing literature. Resources such as StatDx and UpToDate are perfect for these occasions, providing great summaries with citations to the original studies. I guess I didn’t realize during my electives that when residents used these resources, they were essentially practicing EBM and EBR. I think growing up in this day and age with the wealth of high-quality information available within a few mouse clicks, we often take the process for granted. When I hear colleagues say that they aren’t interested in research, it feels almost disrespectful since our lives are made that much easier due to the research of those before us. I think the least we can do is to make some sort of scientific contribution for those that come after us.

So how does this apply to radiology? One can think of EBR as three main domains: diagnostics, screening and interventional.  With regards to diagnostics, classical findings and signs pointing to certain pathologies were previously taught by mentors. However, the concern here is that not all diseases presented with classical findings. With the practice of EBR, there is now data taking these considerations into account. Now we can characterize signs found on imaging with a certain sensitivity and specificity, positive and negative predictive values, all which can influence our post-test probability. Like medicine, radiology is not 100% and EBR reflects that fact while still providing useful information. Perhaps even more important to radiology is the use of EBR in screening. Historical studies have often been riddled with bias, particularly lead-time bias, which resulted in false representation of the test’s effectiveness. In addition, with the increase in the availability of CT scans, radiation dosage is now a realistic concern. With application to entire populations, EBR must be used in making the decision to screen asymptomatic patients, taking into consideration the pre-test probability, the accuracy of the exam, the absolute risk reduction and the potential harms. Finally, the relatively new field of interventional radiology (IR) necessitates the application of EBR. With any field that introduces new procedures and treatments, it is imperative that they are rigorously tested for effectiveness, especially when they incur high costs, as IR does.

As a student who worked in several research laboratories in the past, I was exposed to the scientific method at a young age and understood its value. However it wasn’t until medical school that I learned of clinical trials and EBM. I always thought medicine was more black and white. As I progressed through my career, I gained a better understanding of the intersection between science and medicine and the importance of continuing research as a clinician. Thus, I hope that in the future, I will get the opportunity to apply my past skills in research as an academic radiologist and contribute to the pool of existing knowledge. 

-DW