I am facing a problem regarding sample size calculation of clinical trial.

Currently a drug is used at 2.5 mg for adult and 1.5 mg for children and death rate is 0. Now we want to reduce the drug level to 1.0 mg for adult and 0.5 mg for children.

If I want to keep the death rate at same for new drug level then how many sample should we take to justify.


1 Answer 1


You have a more difficult problem than it seems that you realize. There is not a single answer to this problem - you are describing a non-inferiority trial. You can't "prove" that the death rate stays at zero because you will have a confidence interval for a proportion, whose width depends on how much data exist to support your statement that the death rate is zero.

Here is a place to begin on reading about non-inferiority trials: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC59590

Unfortunately for you, non-inferiority trials often require much larger sample sizes than conventional superiority trials. Good luck!


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