Have just read the link re Symbicort and Serentide posted by Martin 1945
The article makes it quite clear that Symbicort seems to be better at preventing exacerbations. Well that suits me as I'm on Symbicort.
However Serentide is made by GlaxoCline and Symbicort by AstraZenica ... who is the MD involved in reporting and probably funding this article paid by ...... read and you will see ....paid by AstraZenica. So could there be some level of bias here and statistics not being all that they seem ...hmm seems likely.... its so impossible to know.
There is a book by Ben Goldacre called 'Bad Pharma',( he's also written one called 'Bad Science' ... which is quite amusing in a harsh and cynical way) .... neither books are exactly light reads (especially 'Bad Pharma' ... which is very intense) but they sure as hell put a spotlight on the dodgy dealing, fake statistics and financial self interest in the world of health and medicine.
I recommend both, especially if you are interested in understanding how the medical and alternative medical professions are able to provide evidence for treatments that 'apparently' work. Both books opened my eyes and I now feel much wiser in the ways of the medical world of drugs / prescription and hollow promises.