As described earlier, an activity that requires
on-going attention in Clinical Trial
Clinical Trial is the recruitment
and retention of participants in your study. It is
your responsibility as the PI
A clinical trial is a controlled experiment, conducted in human beings, that is designed to evaluate and/or compare the effects of specific regimens or strategies on one or more pre-specified health outcomes in a defined population over a defined period of time. (Clinical Trials: Phase I
Phase I Clinical Trial
testing in a small group of people (e.g. 20-80) to determine efficacy and evaluate safety (e.g., determine a safe dosage range and identify side effects).
, Phase II
Phase II Clinical Trial
study in a larger group of people (several hundred) to determine efficacy and further evaluate safety.
, Phase III
study to determine efficacy in large groups of people (from several hundred to several thousand) by comparing the intervention to other standard or experimental interventions, to monitor adverse effects, and to collect information to allow safe use.
, Phase III(as defined by NIH)
Phase III(as defined by NIH)
is a broad-based, prospective study, including community and other population-based trials, usually involving several hundred or more people, to compare an experimental intervention with a standard or control or compare existing treatments. It often aims to provide evidence for changing policy or standard of care. It includes pharmacologic, non-pharmacologic, and behavioral interventions for disease prevention, prophylaxis, diagnosis, or therapy and includes community and other population-based intervention trials.
, Phase IV
Phase IV Clinical Trial
studies done after an intervention has been marketed to monitor its effectiveness in the general population and to collect information about any adverse effects associated with widespread use.
Principal Investigator (PI) to monitor patient recruitment
and retention in the study. NHLBI
a qualified person designated by an applicant institution to direct a research project or program, oversee scientific and technical aspects of a grant and the day-to-day management of the research.
National Heart, Lung, Blood Institute (NHLBI) program staff
will also monitor enrollment at least annually via your progress
report. Some studies will provide enrollment information
more regularly but communication between NHLBI and the investigator
about patient accrual is encouraged. The policy on Terms
and Conditions for Accrual of Research Subjects in Research offers
further information on single-or multi-center studies that
expect to recruit 150 or more subjects.
National Institutes of Health (NIH)
the United State's medical research agency, a federal government agency composed of diverse Institutes and Centers
that conduct and support biomedical and behavioral research. NIH Homepage
Institute that provides leadership for a national program in diseases of the heart, lung, and blood as well as blood resources, sleep disorders and the Woman's Health Initiative. NHLBI Homepage
The Office of Research on Women's Health provides an Outreach Notebook and Frequently Asked Questions on the topic of recruitment and retention of women and minorities as research subjects with practical applications for conducting NIH-funded research.
Page Last Updated: February 2011
Content Manager: ClinicalResearchPolicyManager@nhlbi.nih.gov