A news release by Loyola Medicine covers what it called a “groundbreaking” study that measured heart rate variability to help differentiate between major depression and bipolar disorder. It adds this would be a “major breakthrough in psychiatric and primary care practices” — made possible by a “simple 15-minute electrocardiogram.”
We caution against the use of such language in a news release because medical research rarely uncovers earth-shattering, dramatic findings. This study is no different and is actually not the first of its kind. The news release also uses ambiguous terminology when revealing the study’s findings, such as the word “significant.”
Many details on the study design, including limitations and funding sources, are left out. There is no discussion of costs, and no data are given to back up the news release’s claims. It also would have been helpful to note how major depression and bipolar disorder are traditionally diagnosed.
The news release does a good job summarizing the profiles of both conditions, including the consequences of misdiagnosing bipolar disorder as major depression.
Clinicians diagnose major depression and bipolar disorder based on subjective psychiatric evaluations, such as through interviews and questionnaires. Lab tests and physical exams are usually performed to rule out other physiological conditions. Currently, no reliable, objective, psycho-physiological markers are available to aid medical diagnosis. If there were a quick, noninvasive and cost-effective test to objectively differentiate the two, that certainly would be newsworthy to clinicians and the general public.
According to CostHelper.com, patients with health insurance typically pay between $30-$100 in copays for both the electrocardiogram (ECG) and its analysis. Uninsured patients can expect to pay $500-$3,000 in total.
Since costs are not discussed in this news release, we give it a Not Satisfactory rating here.
No numbers are given to support the claims of the news release. Instead, readers are only told that subjects with major depression had “significantly higher RSA” (respiratory sinus arrhythmia) than those with bipolar disorder. Exactly what does this mean? How distinctive was the pattern seen in participants with depression as compared to those with bipolar disorder?
In addition, the news release states that patients with bipolar disorder had “higher blood levels of inflammation biomarkers than patients with major depression.” Was this second factor required to define the differences between participants?
We caution against the use of the word “significant” in this context, since it likely means “statistically significant” — which means the result is probably true or not due to chance. However, this doesn’t mean that the result provides meaningful information to clinicians and patients.
No further information is given on the findings of the study.
We would have liked to have seen some numbers here to put “significantly higher” and “higher” into context, which is why we rate this one Not Satisfactory.
An ECG is a safe procedure and records the activity of the heart. Minor discomfort may be felt when the electrodes are removed — similar to when a bandage is taken off. In rare instances, a reaction to the electrode adhesive may cause redness or swelling where the patches were placed.
There is no risk of an electrical shock during the test, since the electrodes placed on the heart do not emit electricity.
But all tests carry the risk of false positive results and those risks are magnified in people with a low risk of disease. Take for example, evidence of ischemia — a situation when blood flow (and thus oxygen) is restricted or reduced in a part of the body. A false positive finding of ischemia on an ECG can lead to more invasive testing in an otherwise healthy adult without evidence of heart disease.
Since harms, including the risk of false positives or over-diagnosis, are not addressed in the news release, we rate this Not Satisfactory.
We’re not given much information on the study design, including limitations of the evidence. Only vague information is given on the “special software packages” that were used to convert and correct the data.
The news release states that heart rate variability measured by an ECG indicated whether subjects had major depression or bipolar disorder. But the actual journal article found that researchers considered heart rate variability together with higher levels of inflammatory markers to distinguish between bipolar disorder from major depressive disorder.
The news release also does not mention the lack of a control group in this study. That’s troubling. Instead, participants with major depression are directly compared to those with bipolar disorder. When there’s no control group, it’s helpful to know what the baseline findings are in healthy unaffected controls so that we understand how all the results stack up against each other.
We would have liked more details on the study, which is why we rate this one Not Satisfactory.
There is no disease mongering in this news release.
The news release does not disclose the study’s funding sources or any possible conflicts of interest. The specialized software used in the study was developed by one of the authors. The University should disclose whether or not it holds patent rights on the software.
For this reason, we rate this one Not Satisfactory.
The news release is silent on alternative strategies. Both depression and bipolar disorder are currently diagnosed on the basis of a thorough psychiatric and medical examination. Clinicians then examine findings and criteria for the disorders in the Diagnostic and Statistical Manual of Mental Disorders by the American Psychiatric Association. These methods were likely used to distinguish between the two cohorts of participants in the study. Other methods under study include the identification of unique metabolic compounds in urine as a method of distinguishing between the two disorders.
Since the news release does not describe the traditional methods of diagnosing bipolar disorder and depression, we rate this one Not Satisfactory.
Although electrocardiograms have been widely used in clinical practice since their introduction in the early 1900s, the specialized software developed by one of the authors is likely not widely available. Although implied in the release, we would have liked to have seen an explicit statement about general availability and for this reason we rate this Not Satisfactory.
From the news release, it’s hard to determine what exactly is new in this study.
A Google search yields a similar study published in the IEEE Journal of Biomedical and Health Informatics. In this 2016 study, researchers analyzed ECGs and investigated heart rate variability of 14 bipolar spectrum patients to predict future mood states. On average, the accuracy of such predictions was 69 percent.
Another 2002 study published in the Journal of Affective Disorders looked at levels of respiratory sinus arrhythmia to predict the course of major depressive disorder.
If the news release uses terms like “groundbreaking” and “major breakthrough” (see the unjustifiable language section), we especially need more context on exactly how this research differs from other studies and what it brings to the current body of literature.
We rate this one Not Satisfactory.
The news release uses terms like “simple electrocardiogram,” “groundbreaking” and “major breakthrough.” We advise against the use of such words, since they are misleading. In medical research, rarely do we see “breakthroughs” from “simple” procedures. More often than not, there are caveats attached to such studies.
For these reasons, we rate the news release Not Satisfactory here.