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Invasive treatment of CCSVI is unethical, even in clinical trials, because of “egregious” methodological problems with the single study that supports it, experts argue.
Recent independent studies “not only cast doubt on whether CCSVI is the cause of MS, they call into question whether CCSVI exists at all”, according to a critical analysis published in the Archives of Neurology.
The greatest problem with the results of the controversial study by Pablo Zamboni and colleagues was the apparent confounding of CCSVI treatment with the initiation of disease-modifying therapy, the authors said.
Sixty-five patients were reported to have significantly few relapses and decreased rate of lesions on MRI following percutaneous transluminal angioplasty (PTA).
But the critical analysis showed there was very good reason to think most of these patients (67%) began disease modifying treatment at the start of the treatment trial.
In addition, there was no control group and therefore no blinding of the neurologists or accounting for the placebo effect
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Zamboni’s earlier paper reporting that CCSVI provided negative and positive predictive values for MS of 100% had no description of how the investigators were blinded.
It appeared that the main interpreting physician in the study was Zamboni himself, raising doubts regarding the objectivity of his interpretations.
Three independent studies conducted through 2010 and 2011 were unable to replicate Zamboni’s prevalence findings, the results of which suggested the venous anomalies were “simply anatomical variants and not pathological”, the review authors said.
Finally there was little reason to think CCSVI would cause MS based on the famous Bradford-Hill criteria for determining causality in biology, they said. The theory failed to satisfy the important criteria of biological plausibility, coherence (with other known data) and analogy (with other disease models).
“Invasive research investigations into treatment of CCSVI are inappropriate until the question of whether CCSVI exists in MS is settled,” they concluded.
Dr Bill Carroll, scientific chairman of MS Research Australia would not say whether or not he agreed with the opinion in the critical review.
Michael Slezak
Source: Neurology Update © Reed Business Information 2011 (26/07/11)
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