Why NOT to Trust the FDA ?

The sponsor showed Timed Walk Responder rates were higher with fampridine treatment
compared to placebo in both pivotal trials, yet the clinical meaningfulness of the benefit remains
unclear. Though more patients on fampridine appear to walk faster, the magnitude of the
improvement in walking speed suggests the improvement lacks clinical significance. The
responder variable is limited by its ignoring the importance of the extent of improvement in
walking speed. So, a small benefit in many patients given the treatment can result in a positive
trial even in the absence of a clinically meaningful benefit. Though there is a change in walking
speed from baseline with fampridine treatment, the magnitude of the change was not large
enough for the average walking speed during treatment to differ from placebo. This suggests the
sponsor’s responder analysis may not be sensitive enough to determine the clinical usefulness of
the treatment.