Multiple comparisons of repeated measured response: issues of assessment of prolongation of QT interval in thorough QT trials.

The primary objective of a thorough QT clinical trial is to demonstrate the lack of QT prolongation induced by the test treatment. The ICH E14 guidance defined drug-induced prolongation of QT interval as evidenced by an upper bound of the 95% one-sided confidence interval around the mean effect on QTc of 10 ms. Furthermore, it defined a negative thorough QT/QTc study as one in which the upper bound of the 95% one-sided confidence interval for the largest time-matched mean effect of the drug on the QTc interval excludes 10 ms. Conventionally, this objective is tested with the intersection-union test by testing the mean difference between the test treatment and placebo of QTc changes from baseline at each of the matched time points. The multiple-comparison nature of the test leads to higher false positive rate when comparisons are made repeatedly at multiple time points. Many approaches have been proposed in the last 5 years in order to improve the efficiency of the test. In this article, we survey and discuss some of the approaches.