Original date: March 1, 2014
Rhetorical Analysis of Seriburi, Ndukwe, Chang, Cox, and Wormser’s Article
DISTORTED DIAGNOSIS IN CLINICAL PRACTICE
Analysis of Seriburi, Ndukwe, Chang, Cox, and Wormser’s Article
Published in 2012, the article “High frequency of false positive IgM immunoblots for Borrelia burgdorferi in Clinical Practice” was authored by a handful of reputable doctors and infectious disease control experts with the aim of persuading their audience that many Borrelia burgdorferi IgM immunoblots are falsely positive, thus not indicative of active infection in their patients. This particular topic has not undergone systematic studies in a clinical setting, which is one of the motivators for writing the article. The authors set out to argue that the high number of false positives have resulted in a number of potentially harmful, unnecessary antibiotic treatments as well as avoidable expenses. The authors outline this thesis in an accompanying abstract as well as within their introductory paragraphs.
This article is targeted at an audience of infectious disease experts as well as other medical-minded professionals, using medical language and assuming their readers have an existing understanding of what IgM and IgG antibodies and immunoblots are. Despite being drenched with medical jargon and the presumed knowledge of its readers, the article is relatively easy to read, not limiting it to only their intended audience. As with most scientific articles, the authors are authoritative in their tone and do not freely allow their audience to make inferences, rather the authors use their authority, cited sources, and statistical evidence to tell the audience what their conclusions are. This particular article uses 15 sources for backing up their claims and presenting information, mostly consisting of published journal articles, editorial commentaries, and published reports.
Of their 15 sources, 7 were authored by the article’s coauthor G. P. Wormser, which could easily remove the credibility of the article given the potential conflict of interest in persuading the article’s conclusions. Fortunately, the authors simply conclude that more research is required on this particular topic. Using a rhetorical pattern of cause and effect, the authors are able to clearly present their information and understanding, breaking down the article into subsections for their introduction, methods, analysis, results, discussion, and so forth.
Some of the statistical information that they present is shown in table format as well as an image of an IgM immunoblot showing a weak band, which they project as being often over-read in clinical practice. In order to better prove their point, they could have included another table showing their full patient load and their presentation and IgM results. This would have allowed their readers to better understand how they were assessing and interpreting their findings. The authors chose to examine the blood serology of patients already being seen at the coauthor G. P. Wormser’s clinical practice. This allowed access to 249 patients seen between September 2007 and June 2010. Each patient was referred for possible Lyme Disease either by a medical doctor or through self-referral. In order to analyze the patients’ blood serology, the authors first had to come to an agreement on the factors they would use to determine a false positive.
The authors established their false positive requirements using five main criteria, as follows: They wanted to ensure that the patients satisfied the Centre for Disease Control criteria for seropositivity, though they did not explain in their article what this criteria was. The authors took liberty in deciding whether or not these patients were likely to have been exposed to ticks and assumed false positive based on low likelihood. They assessed the patients’ signs and symptoms, interpreting them to see if they were indicative of early Lyme Disease. They chose to disregarded any positives that presented during the winter months. Lastly, they decided to retest the individuals after 4 weeks to see if they could reproduce seropositivity. To back up this last requirement, the authors used citations from 1993 and 1996, which is heavily outdated in the medical world.
Using a convincing tone of authority, the authors lead the readers to believe that seropositive results during the winter months are negligible, though they failed to provide references to back up this notion. The authors make this claim using deductive reasoning based on their own anecdotal clinical experience regarding the lack of observed erythema migrans skin lesions presenting during the months, which include the time between December and March. This lack of presentation is not odd considering that people tend to wear more layers during those months and may not become aware of potential lesions, making this logic ineffective. This is potentially negligent as the bacterial infection can occur at any time during the year, though might not present clinically immediately after infection onset. The authors fail to use convincing logic to dismiss the validity of positive tests during the winter month, yet their presumptive tone easily influences their readers into believing the assertion that positives are negligible during the winter period.
In the interest of transparency, Wormser declares that he received a research grant from Immunetics, Inc., which manufactures the C6 ELISA immunoblot test, which happens to be the same test which was praised in their concluding paragraph as having “shown promise” if it were to be substituted in for the currently recommended second-tier test. Attempting to maintain an unbiased tone, the authors disclose a few limitations they encountered during their retrospective study, such as the exclusion of specificity in the readings of serological tests performed in commercial laboratories. They also touch on their use of anecdotal discussions with other infectious disease doctors prompting their belief of high false positives presenting in clinical practice. They declare that the best course of action for evaluating the IgM readings would have been to retest the positive IgM blood serum and have it be read by an experienced reference laboratory, which was not possible in this retrospective study due to some of the positive results having been done in the past and the respective serum samples had already been disposed of.
The authors go on to boast that “objective and reasonable criteria were used to classify the serologic results in this study as likely to be false positive.” Note that the authors use the word “likely” to escape blame by avoiding strong, concrete assertions.
Although they say that “additional research on this topic is warranted,” they are uncompromising in their stance, going so far as to claim that the IgM immunoblot should be removed outright as a serological test in the diagnosis of Lyme Disease. Effectively, the authors were successful in concluding their thesis statement that there are a high number of false positives in clinical practice, blaming a good majority of them on the potential over-reading of weak bands on the IgM test strip. They use some faulty logic in their reasoning for discounting positives, but back up others with more concrete allegations, including some readings neglecting the CDC criteria for diagnosis. The err may be found in the diagnostic criteria rather than the serological tests, but this is more semantic than it is scientific.