The success of any clinical trial depends upon adequate enrollment. Enrollment difficulties may be responsible for 30% or more of all early terminations of phase III studies.1 Because nearly 90% of the world’s population lives outside of North America and Western/Central Europe, there is a push to globalize clinical trials to broaden enrollment potential.

Of the roughly 6 billion people outside North America and Western/Central Europe, many are clustered in cities, where qualified sites tend to be large hospitals that serve significantly more patients than the average US site.2 Concentrated populations in Russia and Eastern Europe often lead to enrollment rates that are up to 20 times faster than in the US or Western Europe.3 In some countries, such as China, India, and Brazil, rapid enrollment can often offset slower regulatory and ethics approval timelines.

However, performing global studies can add complexity at several stages of the study process. Countries can have unique issues related to available resources, standards of care, and cultural perceptions. The following practical strategies can help minimize unforeseen complications when working in new countries.

  • Choose service providers with regional knowledge. This is crucial for setting up the proper trial framework and training investigators for collecting good data.
  • Consider global differences in resources. For studies that need specialized equipment (eg, -80°C freezer, centrifuge, laptop for data entry), the sponsor must decide early in the process whether to provide the equipment or require sites to provide it. Such issues may be particularly important in developing countries where resources are limited.
  • Research selected sites. Taking the time to ensure that selected sites have the appropriate qualifications, staff, motivation, support, and patient population for a particular study may slightly delay site initiation, but this time will be recouped with more consistent enrollment.
  • Clearly spell out eligibility and ineligibility criteria. While trials with more restrictive criteria are often more difficult to enroll, clear specifications will help the site better estimate the number of potential patients in their population and decrease the screening failure rate. Loosely-defined criteria are also more likely to generate questions from sites and IRBs/ECs and require time-consuming and costly protocol amendments.

Please join me later this week for a FREE webcast – The Joys and Woes of Clinical Trial Start-Up: A Global Perspective – where I’ll share more insight.   


  1. Parexel Consulting. Paraxel Biopharmaceutical R&D Statistical Sourcebook, 2012/2013.
  2. PriceWaterhouseCoopers. The Changing Dynamics of Pharma Outsourcing in Asia: Are You Readjusting Your Sights? Accessed March 11, 2012.
  3. ClinStar. Press Release: ClinStar to Present at Outsourcing in Clinical Trials Europe. May 1, 2012.

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