In multisite trials, what should be specified regarding enrollment?

• A. The total number of subjects planned to be enrolled
• B. The site locations and infrastructure
• C. The randomization scheme per site
• D. The numbers of enrolled subjects projected for each trial site

Answer: (D)

When planning a multisite trial, the enrollment plan must specify how many subjects are projected to enroll at each site. This site-by-site projection provides the most actionable roadmap for feasibility, recruitment monitoring, and timely study completion. It allows you to spot sites that may underperform and adjust resources or strategies accordingly, ensures the overall sample size is achievable within the timeline, and supports budgeting and regulatory reporting with a clear picture of enrollment distribution.

While knowing the total planned enrollment is important, it doesn’t show how recruitment will unfold across multiple sites, which is crucial for multisite feasibility and management. Site locations and infrastructure affect feasibility but don’t specify enrollment targets. The randomization scheme deals with allocation to arms, not with how many participants are expected at each site, so it isn’t the enrollment detail that anchors multisite planning.