So I am heading off to Las Vegas for an MS conference this weekend to discuss the development of newer and more meaningful outcome measures in MS. For the past 20 years we have used relapse rates (the number of relapses during the trial divided by the duration of the trial) as the main outcome measure in our clinical trials. For those of you who have read my blogs you already know this is not the best way to determine the effectiveness of a therapy; first, relapse rates are weakly linked to future disability, the main thing we are trying to prevent with our treatments; second, relapse rates naturally decrease over time making it difficult to determine if a person is staying relapse free because they are getting older or because they are taking a useful therapy. This also creates a problem determining the effectiveness of a drug in patients who rarely experience valid relapses (think progressive MS). Most trials attempt to solve the latter problem by attempting to measure the degree of disability over time, but the main disability outcome measure in use (called the EDSS) is insensitive to change over the short duration (2 years) of a clinical trial. In all fairness to the pharmaceutical companies they are well aware of the problems with these outcome measures, but the FDA still requires them to use them in phase III clinical trials. This means that following the completion of a successful phase III trial and approval of a drug by the FDA, we still do not know enough about the long term effectiveness of the drug compared to a placebo and virtually nothing about the comparative effectiveness of different therapies. It has become commonplace for most therapies to report 40-50% reductions in relapse rates, 20-30 % reductions in disability progressive and 70-80% reduction in new MRI lesions. Very few therapies report group benefits in excess of these numbers. We also know very little about the probable effectiveness of a drug in any individual patient. Our goal in the future is to take the guesswork out of these treatment decisions but to do so will require new and innovative outcome measures and trial designs. More later. -- Dr. Kinkel
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