Devita, Hellman, and Rosenberg's Cancer

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Chapter 16•Design and Analysis of Clinical Trials 187

Question 16.15. Which of the following is NOT true for therapeutic equivalence (or non-

inferiority) trials?

A. Therapeutic equivalence trials are designed to test similarity, as mea-

sured by a clinical end point, between the experimental drugs and the

standard treatment.

B. Because it is impossible to prove equivalence in true sense, in practice

therapeutic equivalence will be accepted if the difference in efficacy

is within a prespecified level ().

C. The traditional superiority trials cannot be used to prove equivalence

because a “negative” finding may be simply due to inadequate sample

size.

D. A trial designed to demonstrate therapeutic equivalence requires

fewer patients because it usually allows a relatively large type I

error.

Question 16.16. Therapeutic equivalence trials often express results as an estimate of dif-

ference between two treatments with a 95% confidence interval. Which

of the following statements about the 95% confidence interval is NOT

correct?

A. The confidence interval is a range of values consistent with the

observed difference, given the precision with which the trial can mea-

sure that difference.

B. The trial estimates that in 5 of 100 cases the true difference will fall

outside the 95% confidence interval.

C. It is unlikely that the true difference is smaller than the lower limit or

larger than the upper limit of the confidence interval.

D. If the confidence interval includes 0, then the trial has shown that the

two treatments do not differ.

Question 16.17. Which one of the following describing the pros and cons of Bayesian

methods in planning clinical trials is NOT true?

A. In the traditional statistical (frequentist) methods, the treatment effect

is regarded as a fixed but unknown parameter, and the likelihood of

the parameter is described using a probability derived from observed

frequencies in a defined distribution. In contrast, a Bayesian statistical

method assumes that the treatment effect itself is a random quantity

drawn from a prior distribution.

B. Bayesian methods are widely applied in planning Phase III trials.

C. Because Bayesian methods can incorporate information from preclin-

ical studies and sources outside of the trial, many designs for Phase I

and II trials have been developed within a Bayesian framework.

D. The prior distribution of parameters heavily influences the meaning-

fulness and interpretation of Bayesian-based clinical trials.