Patient Recruitment Feasibility: Defining clinical trial feasibility and establishing a formula for patient recruitment success.

Posted: May 30, 2012
Applied Clinical Trials Online.
KEYWORDS: Logistics/Transportation


A simple formula calculates recruitment or enrollment feasibility for multisite clinical trials.

Why this item may be useful

Recruitment feasibility estimates are an important tool used by study sponsors for achieving timely and cost-effective enrollment. As every clinical trial is different, trend analysis for past trials or sites is not an adequate predictor of future recruitment. This article proposes a formula that can benefit study planners and the clinical trial industry as a whole by providing proactive, early, and efficient recruitment feasibility assessments.


  • This article explores the definitions and parameters of recruitment feasibility.
  • Study planners should consider the following factors that affect recruitment: protocol design, country, sites, and patients. Recommendations for assessing and selecting sites are provided.
  • The author proposes the following formula for calculating recruitment feasibility: e=r*t*s; where e = the number of randomized patients needed; r = the randomization rate (the number of patients per site per month); t = the enrollment time period in months; and s = the number of sites actively randomizing patients.