Trough-to-peak ratios: some statistical considerations.

The trough-to-peak ratio has recently come into prominence as a statistic to evaluate the clinical duration of effect for an antihypertensive medication. The statistic is unusual in that it is defined as the ratio of mean drug effect (compared to placebo) at trough compared to that at peak. There is no corresponding measure available on individual patients. This paper will examine the criteria needed to make the trough-to-peak ratio a useful, interpretable statistic. In addition, other possible trough-to-peak measures and statistics are considered for their potential usefulness in describing diurnal blood pressure (BP) data.