Efficiency of enrollment in a successful phase II acute stroke clinical trial

J Stroke Cerebrovasc Dis. 2012 Nov;21(8):667-72. doi: 10.1016/j.jstrokecerebrovasdis.2011.02.016. Epub 2011 Apr 3.


Background: Recruitment challenges are common in acute stroke clinical trials. In a population-based study, we determined eligibility and actual enrollment for a successful, phase II acute stroke clinical trial. We hypothesized that missed opportunities for enrollment of eligible patients occurred frequently, despite the success of the trial.

Methods: In 2005, acute ischemic stroke (AIS) cases in our region were identified at all 17 local hospitals as part of an epidemiologic study. The Combined Approach to Lysis Utilizing Eptifibatide and Recombinant Tissue Plasminogen Activator (CLEAR) trial assessed the safety of this combination in AIS patients within 3 hours of symptom onset. In 2005, we determined the proportion of AIS patients who were eligible for CLEAR and the proportion that were actually enrolled.

Results: At 8 participating hospitals, 33 (2.8%) of 1175 AIS patients were eligible for CLEAR. Of 33 eligible patients, 18 (54.5%) were approached for enrollment, 4 (12.1%) refused, 1 (3.0%) was not consentable, and 13 (39.4%) were enrolled. Of the 15 not approached for enrollment in the trial, 10 were evaluated by the stroke team; 7 received recombinant tissue plasminogen activator. Enrollment was not associated with night or weekend presentation.

Conclusions: Although the CLEAR trial was successful in meeting its delineated recruitment goals, our findings suggest enrollment could have been more efficient. Three out of 4 patients approached for enrollment participated in the trial. Eligible patients who were not approached and those treated with recombinant tissue plasminogen activator but not enrolled represent targets for improving enrollment rates.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Clinical Trials, Phase II as Topic / methods*
  • Drug Therapy, Combination
  • Eligibility Determination
  • Eptifibatide
  • Female
  • Fibrinolytic Agents / administration & dosage*
  • Fibrinolytic Agents / adverse effects
  • Humans
  • Kentucky
  • Male
  • Middle Aged
  • Multicenter Studies as Topic / methods*
  • Ohio
  • Patient Selection*
  • Peptides / administration & dosage*
  • Peptides / adverse effects
  • Randomized Controlled Trials as Topic / methods*
  • Retrospective Studies
  • Sample Size*
  • Stroke / diagnosis
  • Stroke / drug therapy*
  • Thrombolytic Therapy* / adverse effects
  • Tissue Plasminogen Activator / administration & dosage*
  • Tissue Plasminogen Activator / adverse effects
  • Treatment Outcome


  • Fibrinolytic Agents
  • Peptides
  • Tissue Plasminogen Activator
  • Eptifibatide