Monday, March 19, 2012

1 The Phenomenon Of ‘Chronic Lyme’; An Observational Study

Recently, the results of an observational study on chronic Lyme disease in Norway were published in the European Journal of Neurology. (The full text of the study is behind a pay wall on Wiley - but otherwise you can read the abstract online.) According to the National Institute of Health (NIH) clinical trials database, the purpose of the study was:
"... to chart clinical and laboratory findings in Norwegian patients with symptoms attributed by themselves or their doctor to ongoing chronic Bb infection. Objectives are to assess laboratory findings in relation to established diagnostic criteria and to form a picture of the burden of symptoms and illness perception in this group of patients. The study is essentially exploratory, and is supposed to raise rather than to test hypotheses."
Based on this, it sounds like the authors' original expectations for this study were that the researchers would find out in a given population that among those who either suspect they have chronic Lyme disease and have it - and those who suspect they have chronic Lyme disease and don't have it - that it would be discovered what clinical differences and diagnostic markers would set them apart.

But the abstract doesn't indicate what the criteria are for a case definition of chronic Lyme disease if the researchers had one in mind. Rather, it indicates that of the patients enrolled in the study, there was no evidence that any patient had an existing infection with Borrelia burgdorferi.

The following comments are strictly preliminary and based on the content of the abstract only - a more detailed review is in order once the full text has been read:

First, I was disappointed to find out that the total enrollment expected for this study was a mere 30 participants - and in the actual study, there were only 29 enrollees. This is a very small pool of applicants, and I don't think the data can be extrapolated to fit a large group of people - or even more so, a large group of people from an area which is highly endemic for Lyme disease.

Second, this study in no way set out to solve the problem of whether or not chronic Lyme disease is a real condition - I don't think that was the researchers' goal. Their goal was to characterize those people who either self-reported that they thought they had chronic Lyme disease based on their symptoms or their doctors suspected they had chronic Lyme disease based on their symptoms. Nothing less, nothing more.

It would have been more productive for patients had the researchers taken additional steps to determine what exactly the cause of these symptoms were. But the study was not designed to take those additional steps and just left us with these basic data points:
  • Twenty patients (72%) had symptoms of an unknown cause; of them six met the criteria for Post Lyme disease syndrome (PLDS).
  • Fourteen patients (48%) had the presence of anti-Borrelia burgdorferi antibodies.
  • Eight patients (28%) had other well-defined illnesses.
The researchers stated, "None had evidences of persistent Bb infection, but whether current diagnostic criteria are functional in patients with longstanding complaints is controversial."

Looking at all of this, I'm not sure how to even interpret the initial data shared in the abstract... When those 72% are discussed - of which six patients met the criteria for Post Lyme disease syndrome - are those six patients exclusive of the fourteen patients with anti-Borrelia burgdorferi antibodies or are they inclusive?

If it's exclusive, then twenty of the twenty nine patients have evidence of some relationship to a Borrelia burgdorferi infection. If it's inclusive, then it's only fourteen patients who have evidence of this relationship.

But let's assume they are inclusive, and only fourteen had evidence of anti-Borrelia burgdoferi antibodies. Even if only 48% of the patients studied already have a history of exposure to Borrelia burgdorferi and continue to have persisting symptoms, I think that counts as evidence towards a relationship between Lyme disease and persisting symptoms. Either as a trigger or present causative agent. The researchers themselves state that this is at least partly the case, by reporting that, "sequelae from earlier Lyme disease were probable as main explanatory factor in some cases."

That said, a whopping 72% of patients had symptoms of an unknown cause. So what did they have? It is unknown to me if the issue of seronegativity was considered in patients' reports, whether or not patients with positive antibodies were tested for other conditions with cross reactive antibodies, or whether or not patients were studied for evidence of other tick-borne illnesses.

What is known, however, without having access to the full text is that patients had their blood tested and their CSF studied for any abnormalities and the presence of intrathecal antibodies, as shown in Table 1 of the Supporting Information section. And what is found there leaves me questioning the results - at least in part.

For example, the first patient mentioned in the "unknown causes" category is a 43 year old male who is both IgM and IgG positive for Borrelia burgdorferi antibodies, had 78 weeks of IV antibiotic treatment, and yet is not considered by their definition to have Post Lyme disease syndrome because there was "no documented episode of Lyme disease". This is puzzling - if someone has serological evidence of Lyme disease and they continue to have symptoms - wouldn't this indicate by the most conservative view that the patient at least has Post Lyme disease syndrome (regardless of the controversy over persistent infection)?

That there was no earlier documented acute case of Lyme disease seems to be at the heart of determining whether or not a patient is at least meeting the criteria for Post Lyme disease syndrome. According to this study, it seems that if there was no earlier record of an EM rash and evidence of a tick bite by a doctor, then the patient is disqualified from a Post Lyme disease syndrome diagnosis. Why this is the case when there is evidence patients do not always recall a tick bite, a rash is not always present (and this is even more likely in Europe based on some research), and there are documented cases of patients who are asymptomatic in the early stage - only to be profoundly disabled by symptoms later - is unknown. It doesn't make sense to me.

It would have been interesting had the researchers ran epitope and proteomic analysis of patients' CSF and confirmed earlier research completed by Chandra/Alaedini and Schutzer - so far, I see no evidence this was done; I would expect such an analysis would be included in the abstract. I would also like to know what - if any - immunological factors were examined in each of these patients.

After reading this abstract, what one is left with is are more questions about the nature of chronic Lyme disease than answers.

What is a good starting point for more research of this nature?

What is the relationship between persisting symptoms and infection with Borrelia burgdorferi?

The abstract for this study and its supporting information do not answer these questions. All this study does is begin to examine what relationship there is between Borrelia burgdorferi and persisting symptoms in a small group of people.

References:
http://onlinelibrary.wiley.com/doi/10.1111/j.1468-1331.2012.03691.x/abstract
http://clinicaltrials.gov/ct2/show/NCT01151150
http://www.sciencedirect.com/science/article/pii/S1521661611001914
http://www.plosone.org/article/metrics/info%3Adoi%2F10.1371%2Fjournal.pone.0017287



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1 comment:

  1. Since I posted this, I discovered that the full text of the paper contains information pointing to chronic fatigue syndrome as the diagnosis for patients with persisting symptoms. To that I say: "But what is the cause of the chronic fatigue?"

    Clearly the answers are not here.

    ReplyDelete

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