Why +FEV1% improvements shown from inhaler trials are quite significant...
CF lung function deteriorates continuously. FEV1 normal function is more than 80%, while severe cases are less than 40%, and transplant qualifications are met at 20%.
The simple fact for CF sufferers is that it ends with death or transplants because lung function becomes too poor.
Considering placebo arms consistently perform at 0% or lower +FEV1% improvement levels illustrates how significant even 1% superiority in an inhaler arm can be for sufferers. That could perpetually stave off the less than 25% FEV1% level from being hit years, even more than a decade.
That's why TOBI, despite it's relatively bad efficacy now, will continue to rack in excess of $400M.
Don't undervalue the impact that these inhalers have, even if it's a few percentages.