Dear all,
Everyone knows that the optimal strategy for analysing an RCT to
compare two interventions is by Intention to Treat (ITT). This means
that you analyse the study by what treatment the subjects were
randomised to, and not what they actually received. Most also know
that if one is trying to prove equivalence of treatments rather than a
difference, then ITT is not a good idea, since protocol deviations
will bias the results towards what you want to prove.
Suppose you have a clinical trial with clinical and cost outcomes.
Your expectation is that the two treatments will be clinically
equivalent, but you want to prove that one is cheaper. Should you
analyse by ITT? For the clinical outcomes you have an equivalence
trial and for the cost outcomes a difference trial.
Have others come across this and what should one do?
Mike
Professor Mike Campbell
Institute of Primary Care and General Practice
University of Sheffield
Community Sciences Centre
Northern General Hospital
Sheffield S5 7AU
Tel 0114 271 5919
Fax 0114 242 2136
e-mail [log in to unmask]
http://www.shef.ac.uk/michaelcampbell/
http://www.shef.ac.uk/medical-statistics/
|