Abstract #301166

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JSM 2003 Abstract #301166
Activity Number: 219
Type: Contributed
Date/Time: Tuesday, August 5, 2003 : 9:00 AM to 10:50 AM
Sponsor: Biopharmaceutical Section
Abstract - #301166
Title: Actual Change Versus Percentage Change as an Endpoint in Clinical Trials
Author(s): Pandurang M. Kulkarni*+ and Craig H. Mallinckrodt
Companies: Eli Lilly & Company and Eli Lilly & Company
Address: 11246 Knightsbridge Lane, Fishers, IN, 46038,
Keywords: percent change ; endpoint ; clinical trials ; sample size
Abstract:

In many clinical trials from various therapeutic areas, the efficacy of a treatment is assessed using percentage change from baseline as the response variable as opposed to the actual change. For instance, studies in bone mineral density, hot flashes, and lipids commonly use percentage change from baseline as the primary endpoint. Percentage change may be more intuitive to interpret than the actual change. For example, a 10 percent improvement vs a change of 10 mm on a visual analog scale for pain. However, choice of endpoint can have important implications. Therefore, we explored the impact of using percentage change vs. actual change in several clinical trials, where baseline severity was restricted and unrestricted, to gain a practical understanding of these implications. Choice of endpoint influenced variation, power, sample size, and interpretations, leading to important differences in understanding of treatment effects and the underlying disease mechanisms. These factors will be discussed and general guidance will be provided, in the context of a regulatory environment, in order to better understand the issues and to help optimize the design of clinical trials.

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