Definitive or Conclusive (Phase III) Clinical Trial

NINDS funds clinical trials that are expected to provide definitive or conclusive answers to significant questions of clinical management or disease prevention. These trials are often called Phase III trials. NIH defines a Phase III trial as: a broadly based prospective clinical investigation which involving several hundred or more human subjects, for the purpose of evaluating an experimental intervention in comparison with a standard or control intervention or comparing two or more existing treatments. Often the aim of such investigation is to provide evidence leading to a scientific basis for consideration of a change in health policy or standard of care. The definition includes pharmacologic, non-pharmacologic, and behavioral interventions given for disease prevention, prophylaxis, diagnosis, or therapy. Community trials and other population-based intervention trials are also included.

Because of the potential public health importance and prospective impact on health policy, NINDS needs to ensure that phase III studies meet the highest standards of scientific integrity as well as participant safety. Thus, it is the policy of the NIH that all NIH-sponsored or -conducted clinical trial monitoring activities be commensurate with the nature, size, and complexity of the trial. The NIH requires that NINDS be responsible for oversight of data and safety monitoring to ensure that a monitoring system is in place and is appropriate for a study, and that the Institute is informed of recommendations emanating from monitoring activities. The following documents, NIH Policy for Data and Safety Monitoring (released on June 10, 1998) and Further Guidance on Data and Safety Monitoring for Phase I and Phase II Trials (released on June 5, 2000) provide the detailed description of these policies.