Q&A: Problem with Diagnosing, but Not Overdiagnosing, mTBI

August 19, 2015

This Q&A series explores radiology’s role in overdiagnosis in a variety of conditions. Here, we discuss mild traumatic brain injury.

Overdiagnosis is commonly discussed in areas like breast imaging, where screening is widely conducted and media interest is high. While it’s under the radar for other diseases, it’s a big enough topic in the medical world to warrant a dedicated issue in Academic Radiology. Its August 2015 issue is devoted to overdiagnosis, a term used for disease that’s correctly diagnosed, but at the earliest stages when treatment may not be necessary and might even be harmful to the patient. This is in contrast to false positives, when the diagnostic test incorrectly indicates the possible presence of disease.

Overdiagnosis is more prevalent in modern times because the definition of disease has expanded, said Saurabh Jha, MBBS, assistant professor of radiology at the Hospital of the University of Pennsylvania, and guest editor of the Academic Radiology issue. “The rationale is the very intuitive concept that if we catch disease early on, we’ll avoid morbidity and mortality, that prevention is better than cure.”

Through screening, radiologists define the pathway to disease and are the gatekeepers of the technology often validating the diagnosis, since the gold standard of a diagnosis by pathology isn’t always an option.

With more advanced technology, radiologists can see deeper into structures in the body, discovering new (but often innocuous) abnormalities. Another reason for a growth in overdiagnosis is cultural. The division between “diseased” and “healthy” is arbitrarily set.

“There’s always going to be disputes about where the boundary takes place,” said Jha, with nothing magically happening at that threshold where disease is defined. However, in the United States, that threshold is often set at a place where doctors won’t miss any disease, erring on the side of overdiagnosing a person who doesn’t need treatment. “We live in an extremely risk averse environment.”

This Q&A series looks at a number of diseases that may be overdiagnosed in the United States, where we might be “treating health as opposed to solving sickness,” according to Jha.[[{"type":"media","view_mode":"media_crop","fid":"40575","attributes":{"alt":"","class":"media-image media-image-right","id":"media_crop_6130506861294","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"4183","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right;","title":"Jeffrey B. Ware, MD","typeof":"foaf:Image"}}]]

When someone has severe brain injury, the diagnosis is simple, said Jha. But for those with mild traumatic brain injury, imaging can show changes, but should be paired with clinical symptoms for treatment. “It’s important to create the thresholds for diagnosis in such a manner that we err toward underdiagnosis as opposed to overdiagnosis,” he said.

Here’s our Q&A with Jeffrey B. Ware, MD, Chief Resident in Diagnostic Radiology at the Hospital of the University of Pennsylvania.

Why do you think this is an exciting area in neuroimaging?

First and foremost, it holds the potential to improve the care of a challenging medical issue that affects a large number of people including military veterans, athletes, and everyday citizens. Although the consequences of head trauma have long been recognized within the medical community, and no more clearly than by its victims, the use of advanced neuroimaging and data processing techniques have allowed us to visualize the injuries for the first time. This has profound implications for our understanding of the disorder and ultimately of the brain. Though it’s not certain when or if advanced imaging will be used routinely to evaluate individual patients with mild traumatic brain injury (mTBI), the application of these techniques in research has helped us better understand its neurobiological effects. Research is also leading to new insights into how the brain works and how its structure and function are interrelated.

What are your concerns for imaging in this area?

Primarily it’s the potential for misinterpretation and misuse of the imaging techniques. Misunderstanding the capabilities and limitations of advanced neuroimaging techniques could potentially lead to several unintended consequences including misdiagnosis, selection of ineffective treatment approaches for individual patients, and, ultimately, to inappropriate allocation of resources. Along these lines, the use of diffusion tensor imaging (DTI) in evaluating medicolegal claims related to head trauma remains highly controversial. The need to further refine and standardize these techniques prior to endorsing widespread use has been recognized by the neuroimaging community. Future research should also focus on determining the benefits and drawbacks of applying these techniques in routine assessment of individual patients.

Why is overdiagnosis of mTBI problematic?
First, there is evidence that assignment of the diagnosis itself is, in some cases, associated with negative consequences secondary to poor expectations that tend to accompany the label of "brain damage." Additionally, because symptoms developing after head trauma may overlap with those of various psychiatric conditions, there is concern that overdiagnosis of mTBI could result in unwarranted attribution of posttraumatic symptoms to mTBI, leading to a failure to appropriately seek out and treat psychiatric conditions which actually represent the primary problem, or are co-existent with mTBI. In regard to sports-related mTBI, modern professional and even collegiate athletes increasingly face a difficult decision of whether to continue participating in athletic activities after sustaining one or more concussions. Overdiagnosis of brain injury in this context could lead athletes to base these important decisions on inaccurate risk estimation, potentially resulting in unnecessary forfeit of their career and/or passion.

How does labeling someone with m-TBI change their management or life?
This is a very important question, and the answer may vary significantly among individuals affected by mTBI. Research in combat-related mTBI has suggested that labeling individuals with mTBI can be problematic and, in some cases, stigmatizing. On the other hand, it is conceivable that some patients may find relief in learning the cause of their symptoms. This would be particularly true if the diagnosis of mTBI can be made confidently, and lends itself to appropriate and effective therapy. An important area for future research is to determine whether specific patterns of neuroimaging abnormalities can predict response to different therapeutic strategies, ultimately informing us which therapy is most likely to be effective for an individual patient.

You mentioned that thresholds for defining mTBI must be judiciously assigned. Please explain.
The threshold problem is not unique to mTBI. In general, selection of a low diagnostic threshold in hopes of ensuring that a diagnosis is never missed is accompanied by a greater risk that individuals who do not have the disease  will incorrectly be given the diagnosis, and also that the diagnosis will be made in individuals for whom the disease is actually of no consequence. On the other hand, selection of a high diagnostic threshold in hopes of ensuring only those that receive a diagnosis are those who actually have the disease is accompanied by a higher risk that the diagnosis will be missed in a number of individuals. Therefore, it is important that the specific consequences of each approach are carefully considered with respect to the disease in question. Though it may be tempting to use a low threshold in diagnosing mTBI as the cause of posttraumatic symptoms, the potential unintended negative consequences of this approach must be considered and weighed against alternatives.