CLINICAL INVESTIGATION NOTICE

February 19, 2002

TO: Faculty Conducting Human Subjects Research

FROM: Michael J. Klag, M.D., M.P.H.
Vice Dean for Clinical Investigation

RE: Study Sample Size Issue
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It has been brought to my attention that there is some confusion about approved sample sizes for projects reviewed by the Hopkins’ IRBs. I am writing to clarify the policy.

The Office for Human Research Protection (OHRP) expects that IRBs will review and approve a specific number of subjects to be enrolled in a project. A new application submitted for IRB review must state the number of subjects to be enrolled in the first year of the project. When initial approval is issued, approval is granted to enroll only the number of subjects listed in the application for the first year of the project. This number is defined as the number of participants who sign the informed consent document. If this number is reached, enrollment must cease. Enrollment of subjects beyond the initial approved number is considered non-compliance with terms of the project approval. Please keep careful records of subjects enrolled to avoid inadvertent non-compliance.

Thus, if you anticipate that a proportion of subjects will not be informative or will not be eligible to continue in the study after a screening process, you should estimate the sample size accordingly. Subjects who are entered in the screening portion of a project are considered enrolled and the number must be within the bounds of the approved sample size. If you anticipate that you must screen twice as many subjects as will actually continue in a trial, the requested sample size should take this into account.

In order to increase the sample size above that originally approved, a written amendment must be submitted to the IRB. Enrollment may not continue above the original sample size until the IRB approves the amendment. If you wish to amend the sample size at the time the renewal application is submitted, you should clearly indicate this amendment is part of the renewal application and await the final decision of the IRB before proceeding with enrollment.

As always, feel free to contact Barbara Starklauf, the IRB chairs or me with questions. Thanks for your attention to this important issue.

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