The other side of the risk-benefit ratio


A few days ago, I wrote about a drug with “statisticially significant, but perhaps not clinically relevant, effect”:http://www.randomjohn.info/wordpress/2006/09/12/significance-statisticical-and-otherwise/. This is the benefit side of the risk-benefit ratio that the FDA tries to evaluate when deciding whether to approve a drug.

The other side, of course, is the risk. The “Campath”:http://www.fool.com/News/mft/2006/mft06091422.htm story illustrates this issue quite nicely. “Campath”:http://www.campath.com is currently on the market for B-cell chronic lymphocytic leukemia (_i.e._ a form of white blood cell cancer), and Genzyme is trying to develop the drug for “MS(Multiple Sclerosis)”:http://en.wikipedia.org/wiki/Multiple_sclerosis. Campath seems to have beaten its competitor Rebif in a recent Phase II trial (_i.e. it is efficacious if these results are replicable), but a small percentage of patients who took the drug had the life-threatening immune reaction “ITP(immune thrombocytopenia purpura)”:http://en.wikipedia.org/wiki/Idiopathic_thrombocytopenic_purpura. (Note on link: the Wikipedia describes the idiopathic version, which doesn’t have a cause. However, you can get an idea of the reaction for which the cause is known.)

While MS(Multiple Sclerosis) is a chronic disease that requires a major change in lifestyle to cope (as well as frequent trips to the neurologist and periods of being unable to carry out life’s normal activities without at least major help), it is not immediately life-threatening the way that this rare serious adverse drug reaction is. While there is benefit, there is also a major risk. Analysts are not to sanguine about the future of Campath as a MS(Multiple Sclerosis) treatment.

See “here”:http://www.bizjournals.com/sanantonio/stories/2006/09/11/daily26.html for a slightly different perspective (and wildly different headline).

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