Prof Campbell wrote:
<<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?>>
If you have powered the trial for clinical equivalence, you have probably
powered it for cost difference - but you should check - and the trial
protocol ideally should be set up for both types of outcomes. Collecting
economic data as part of clinical trials (RCT in particular) introduces
some problems as the nature of clinical trials usually demands far greater
resource utilisation than is found in the real-world. However, you may
have taken this into account in terms of what economic data you
include/exclude. This is not to say that collecting economic data outside
an RCT is without problems.
I would argue that ITT analysis is most appropriate in most circumstances
as it provides a better picture of the costs of treatment in a real-world
setting. However, one can always choose to restrict the scope of the cost
minimisation analysis to suit the purpose of the study. For example, a
health funder may be interested only in the costs of treatment and is not
interested in the zero costs of those patients that drop out of treatment.
But in either case, I would argue that you need to be consistent in your
analysis - that is, if you use ITT for the clinical outcome then ITT for
the economic outcome as well.
Personal opinion, etc, disclaimer.
Mladen Kovac
Health Economics Manager
3M Pharmaceuticals Australia
email: [log in to unmask]
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