How often must IRB continuing review occur for protocols with more than minimal risk that are enrolling subjects?

Continuing review of research protocols that involve more than minimal risk is typically required to occur at least annually. This requirement serves to ensure that the ethical oversight of the research is maintained throughout the study's duration. Annual reviews allow Institutional Review Boards (IRBs) to assess the ongoing risks and benefits of the study, monitor participant safety, and evaluate any changes in study procedures or protocols that may impact the initial risk assessment.

The annual review process also ensures compliance with regulatory requirements, helping to protect the rights and welfare of the participating subjects. While more frequent reviews could be stipulated based on the study's characteristics or risks, the standard is set at one year for protocols classified as having more than minimal risk.

Other options suggest review frequencies that do not align with the typical regulatory expectations. Six-month reviews might seem appropriate for high-risk studies, but they are not the standard requirement. Two-year intervals extend beyond the allowed timeframe, while reviewing every time the study completes a phase does not adhere to the systematic and regulatory structure set for IRB reviews. Thus, the annual requirement remains the established guideline in the context of IRB continuing review for studies involving higher risk in human subjects.