These days, the CROs and the study sponsors are trying hard to diminish the guesswork during the assessment of the subject recruitment rates at the study feasibility stage. They implement a plethora of strategies, virtual models, painstakingly going through the epidemiology data and even coming up with patient recruitment laws (e.g. Lasagna’s Law: “The incidence of patient availability sharply decreases when a clinical trial begins and returns to its original level as soon as the trial is completed”). Nevertheless, direct input from the potential investigators still plays a significant role in assessing patient recruitment rates in clinical studies. Unfortunately, in many instances, the input from the clinical sites proves to be overly optimistic midway through the study and many sponsors and CROs find themselves struggling for the subjects they need, wishing they would have taken investigators’ forecasts with a grain of salt when deciding how many sites they would need to run a successful study.
There are several reasons as to why the potential investigators may overestimate their recruitment potential during the study feasibility stage and at a qualification visit.