Tuesday, January 26, 2010

XMRV Revisited

Recently Simon Wessly et al, authors of the PLOS article I criticized in a previous post, have fired back at criticisms they are receiving from around the world regarding their patient cohort. Since I believe in giving the Devil his due, I will briefly summarize their reply. They specifically addressed the criticism that their patients are not typical of CFS patients, and that their patients are purely psychiatric cases. They identify several biologically anomalies in their patients, so it appears that not all their patients are 'pure' psychiatric patients. Based on the information presented in their article, it appeared that they had screened out all patients with documented physical anomalies. I don't know enough about the medical details to assess whether the biological anomalies they note are the same as those found by other researchers or whether they are significant in CFS. However, they explicitly state that they do NOT use the Canadian Clinical Consensus because they don't how to use it. (???!) Given that the Whittemore Peterson Institute DOES use the Canadian Clinical Consensus, it is clear that the patient cohorts necessarily differ in significant ways. Different patient cohorts = different study outcomes. No surprise there. The PLOS paper says nothing about the science done by the Whittemore Peterson Clinic. As long as they don't claim their study is a replication study (it isn't), there's nothing to get excited about.
I salute the authors of the PLOS article for defending their patients and asserting them to be as worthy of medical care and research as other patients. Unlike some critics, I don't think they're a cynical bunch of bastards making money for insurance companies off the bodies of their patients. I believe they actually do care about their patients. I think they're wrong-headed in how they go about it. I've met their kind of doctor before: absolutely unshakeable in their certainty that their medical degree means they're right and their patient is wrong.

I also salute them for detecting celiac disease in about 2% of their patients; this is a pernicious disorder that is hard to identify and can make a person absolutely miserable if not treated. On the other hand, such patients are then excluded from a diagnosis of CFS, and some studies have shown an association of gluten intolerance with CFS. They also exclude cancer patients from a diagnosis of CFS, and other research has shown that patients with CFS are at an elevated risk of developing cancer. Thus they have excluded two populations of patients that are reasonably included in CFS research. 

However, the WPI makes no statement regarding celiac disease, so we don't know if it played a role in their patients, either. The WPI statements about cancer patients have been confusing; I have tried to track it down, and I believe they have said that the rate of lymphoma in CFS patients is one of the things that tipped them to look for XMRV, but that they did not include cancer patients in the cohort of 101 patients in their original study. Thus it appears that the WPI and UK patients are similar in this regard. Nonetheless, the utilization of the Canadian Consensus by the WPI and the utilization of the older Fukuda criteria by the UK study are dramatic differences in CFS definition and patient selection which render their study outcomes irrelevant to one another.
Above and beyond the medical implications for the public health that XMRV and CFS pose, the drama being played out in the usually sedate world of medical research is fascinating in and of itself. Somebody is going to take an Oedipal fall before this is all over, and like Oedipus, nobody is going to cry for them when it happens. It's like watching a very close football match, except in this case the outcome actually matters. My health--and yours-depends on it.

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