Toward the end of the “Details are here” link in Frank’s brief post above is this example of prognostic counseling that could well be based on QoL / PRO data of the kind you hope to collect, Karl:
What is an example of the most useful prognostication to convey to a patient? “Patients such as yourself who are at disability level 5 on our 10-point scale tend to be at disability level 2 after physical rehabilitation. Here are the likelihoods of all levels of disability for patients starting at level 4: (show a histogram with 10 bars).”
Notice how the conversation is rooted in (statisticians would say, “conditioned on”) the patient’s current situation. Also, see the difference (-3) in disability levels never enters the discussion; the focus is placed on health states and their meaning. (Consider the modified Rankin scale as a scoring system with meaningfully defined health states, but for which score differences are meaningless.) Finally, uncertainty about the final outcome is conveyed with a histogram.
I wonder if starting from a regulatory standpoint has obstructed your view of the issue, in something like the way that regarding drug dependence as a law-enforcement (as opposed to health-care) problem does. Why not start with the desired prognostic counseling script, and work backward to the trial designs that will support that script?