On July 15, the CFIDS Association of America hosted an XMRV Update webinar featuring Lucinda Bateman, M.D. and Vincent Racaniello, PhD. The recording of the webinar is archived at http://www.cfids.org/webinar/series2010-past.asp#10 and on our YouTube site athttp://www.youtube.com/solvecfs#p/a/u/0/qBfLqeGuzuo. Unfortunately, technical issues cut Dr. Batemans presentation short and she was unable to rejoin the broadcast for the question-and-answer session. She has graciously provided written answers to some of participants most-frequently asked questions. For an overview of XMRV studies in CFS and a list of regularly updated resources, please visit http://www.cfids.org/xmrv/default.asp.
Question: Why dont researchers use the Canadian case definition?
Dr. Bateman: A group of well qualified CFS clinicians met in Canada to create a consensus document that would provide a better clinical working definition of CFS, rather than a restrictive research definition. A research definition, like the Fukuda paper, is intended to identify those who have CFS without any other confounding issues, so that research outcomes will be more clear. A clinical definition is designed to be more inclusive, enabling a provider to diagnose CFS based on a more comprehensive list of typical symptoms. The Canadian definition paper was published in 2003 in the Journal of Chronic Fatigue Syndrome. Unfortunately the JCFS was initially less available except to those who subscribed to the journal. Eventually the information became readily available online, but one must know about it and go looking for it to find it.
So, my answer is that the Canadian definition is not perceived as a research case definition; it doesnt carry the sanction and clout of the CDC definition; and it is not as easily accessible to those researchers not already familiar with the field. I believe there is work going on currently to make the Canadian definition more adaptable to research and more accessible to clinicians generally.
(Note: Dr. Leonard Jason of DePaul University and colleagues in Brussles and New York just published an article titled, The development of a revised CFS/ME case definition, in the American Journal of Biochemistry and Biotechnology at http://www.scipub.org/fulltext/ajbb/ajbb62120-135.pdf.)
Q: Should I get tested now by one of the labs selling XMRV tests? How reliable are the results given our current state of knowledge?
Dr. Bateman: Certainly individuals can make any choice for themselves, if willing to spend the money and take a risk on the unknown. It is my opinion that most people should wait for more progress before ordering XMRV tests. Several reasons not to get tested include the following:
* The tests are not yet well defined in terms of sensitivity and specificity. Hopefully a good test will have a high true positive rate and low false positive rate.
* We dont understand clearly what role XMRV plays in the people who have a positive test.
* We dont have treatments that have been proven safe or effective in the CFS population.
Q: What should I do if I test positive for XMRV?
Dr. Bateman: Stay up to date with the literature and consult with a physician who understands both CFS and our current state of knowledge about XMRV. Volunteer to be part of well designed clinical drug trials. Get information from large established advocacy organizations, such as the CFIDS Association, who are doing their best to keep the CFS community aware of progress and the implications of each new bit of information.
Q: Should XMRV positive patients be worried about sexual transmission?
Dr. Bateman: Thats another good question. The answer is not known yet. So far it hasnt seemed like the presentation of CFS is typical for a disease that is sexually transmitted. But our ability to observe patterns of transmission could be obscured if only a subset of what we now call CFS have XMRV. Then the patterns of transmission might be hidden within the larger heterogeneous group. The question of sexual transmission will be answerable when we have a test that is reliable in both infected people (sensitive) and non-infected people (specific), and when we know how many infected people go on to develop a clinical illness.
Q: What do you think about treating CFS with antivirals or antiretrovirals?
Dr. Bateman: If we can establish the presence of XMRV, prove it is playing a role in CFS, and show that anti-retroviral drugs are reasonably safe and effective, then it will be a very exciting to have access to treatment options. As a physician who has seen patients suffer serious side effects from well-intended, proven and unproven treatments, I am very willing to wait for the evidence. I hope to play an early and pivotal role in this research as it becomes available.
Q: What should I be telling my doctor about XMRV?
Dr. Bateman: I encourage my patients to provide information about XMRV to all of their physicians, but it is up to the physician to pursue ongoing front-line scientific information. Sometimes it takes a long time for scientific information to become evidence-based clinical guidelines, but the better the research, the more compelling it will be for medical providers to become self-educated. Of note, OFFER has a half-day CME (continuing medical education) conference for medical providers coming up on Saturday, September 11, with a lecture on XMRV by Dr. Ila Singh of the University of Utah. Digital recordings will be available online after the conference at www.offerutah.org
Q: Is XMRV related to specific CFS symptoms?
Dr. Bateman: We dont know yet how many people who meet Fukuda CFS criteria, for example, will test positive for XMRV. So it is difficult to say how it relates to symptoms, since in the negative studies so far, sick people with many symptoms dont seem to be infected with XMRV (assuming the test results are accurate). In patients who are found to have XMRV infection, I suspect XMRV may be responsible, directly or indirectly, for many of the symptoms of CFS.