Clinical Trial Efficacy End Points: What to choose?

Dr Michael Silverman of BioStrategics Consulting Ltd., reviews the use of efficacy end points in clinical trials and the needs of the different audiences, including corporate sponsors, scientists and academics, regulatory authorities and the consumer.

The choice of clinical trial efficacy end point for a new product is highly specific to the drug, disease and the objective of the clinical trial. But, to realize success in the marketplace, sponsors must choose the appropriate efficacy endpoint for their drug, which if met, will determine the indications that can be used on the product label; assuming the FDA agrees.

According to Riegelman and Hirsh, 1989, a valid clinical end point must satisfy each of four qualitative criteria:

  • It must be a measure that is appropriate to the clinical question being asked; in other words, it must measure an outcome that is directly relevant to the clinical benefit being sought.
  • I must be accurate, truly measuring the phenomenon in question through some combination of data from test instruments, assessments by the investigator, and reports from patients.
  • It must be complete, capturing data from a sufficient number of patients under study.
  • It must not be influenced by the process of observation, whether through changes in patient behavior or through investigator bias.

In choosing an appropriate endpoint for a clinical study, the trial designers must appreciate that there are multiple audiences for the efficacy data generated by the study, including corporate management, the scientific and academic communities, the regulatory authorities, and the consumers.

Some examples of quantitative measures used for clinical efficacy end points are:

Corporate management may be interested in whether or not the data from the study suggests it is worth continuing to pursue the development of the drug, the so-called, go / no go decision. The scientists may be more interested in how the drug is working. The regulatory authority, in one sense, are the most important audience as they determine whether or not the product can be marketed or not. Using end points that have already been approved by the regulatory authority makes the most sense, but if a new endpoint is being used, then it is necessary to prove that this endpoint is a valid measure of drug success. The consumers will be the ultimate audience, their use of the new drug will depend on number of factors including the drugs efficacy and safety profile, its ease of use, a number of socioeconomic factors, including, cost to them.

I would be delighted to hear your thoughts on these issues, your approaches, or anecdotes about decisions you have faced in similar circumstances. To make comments or ask questions, click on this link.

For more information: go to or send me an email at

Copyright © 2011 BioStrategics Consulting Ltd.


About BioStrategics Consulting Ltd

BioStrategics Consulting Ltd provides a range of management-level clinical development consulting services to the pharmaceutical and biotechnology industries
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