Investigating the effectiveness of rehabilitation professions--a misguided enterprise?

Some research studies investigate the effects of 'professional therapies' (such as physiotherapy) given to certain classes of patient. This presupposes that therapists (a) only deliver treatments and (b) all deliver the same treatment(s), and neither assumption is true. Moreover the study design usually ignores the fact that rehabilitation is or should be a team activity. It is rarely valid to investigate one part of a team's activity in isolation from the activities of other team members. Therefore the research is often flawed, and cannot answer the question(s) posed. Two consequences arise. First, invalid conclusions may be drawn, especially that the input of a therapy profession is ineffective. Second, purchasers may fail to learn that rehabilitation is a team activity, where the team needs to encompass a range of knowledge and skills rather than comprise specific professions, and may stop funding effective rehabilitation by not funding (enough) input from specific professions. The better approach is to investigate the rehabilitation processes and specific interventions that should be specifically described.