Tuesday, January 23, 2007

Blinded Controlled Studies

What happens if a blinded investigator discovers something startling while reviewing the information from a clinical trial? Part of enrolling in a research study is that the subject waives his or her access to personalized care. But how do we draw the line?

This morning, I attended a scientific talk that presented data from a clinical study involving MRI imaging of carotid arteries at risk for plaque rupture and embolus formation. (Those events often lead to stroke.) In one case, an individual initially had no evidence of vascular disease, but three years later, showed a considerably more complex lesion in the vessel. The plaque had ruptured and the lipid core was continuous with the blood flow. Theoretically this is a severe risk for morbidity, but the patient had no symptoms. Just for reference, if that type of lesion was found in an autopsy, the cause of death would be immediately settled.

I was surprised to hear that this patient and his surgeon were kept blinded about the condition. Thanks to the research ethics class I am currently taking, I wondered why the patient was not told. (The notoriously cantankerous professor that hosts the seminar did the favor of asking the question I was wondering about!) The speaker replied that no one has any scientific evidence that a lesion like this actually correlates to stroke. Since this MRI technique is new, and it is the first time that such lesions are measurable in vivo, there could be a large number of folks walking around with this type of problem without experiencing a problem. The study is still going on. Do we have to wait for these folks to die?

I wonder if this 60 year old man just happened to be the pilot on my flight home for New Year's, or the guy that drives my bus, or someone's grandpa...

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