ABSTRACT
It is often the case that a patient with one or more diseases is treated with multiple drugs or therapies at one time. Each drug may be taken in a xed dose or in a dose titration manner to have the dosage adjusted over time to increase the benecial effect or minimize the adverse effects of the drug. Considering these factors, evaluation of the efcacy or effectiveness of a combination drug or therapy can become very complex. If the drugs are to treat different diseases, then a combination treatment seems sensible only when the therapeutic effect of each drug in the combination is maintained, if not enhanced. Statistically, the question of whether the therapeutic effect of each component drug is maintained may need to be addressed via some kind of “noninferiority” statistical inference, which is usually very challenging.
