Which Randomization Methods Are Used Most Frequently in Clinical Trials? Results of a Survey by the Randomization Working Group

Abstract

Background: Randomization is the foundational element of modern randomized clinical trials (RCTs). The proper choice and implementation of a randomization procedure is essential for obtaining credible trial results. Purpose: To survey current practices, gaps and challenges in the application of randomization in RCTs, and identify opportunities for improvement. Methods: An online survey by the Randomization Working Group in 2022 collecting experiences and perceptions on randomization. Results: Of 145 unique respondents, 137 (94.5%) identified themselves as statisticians. The majority of respondents were from academia and pharmaceutical companies. Permuted block randomization, with or without stratification, was the most frequently chosen method of randomization for RCTs. Interactive Web-Based Response Systems (IWRS) and “in-house” or a combination of “in-house and outsourced” randomization models were found to be most common in practice. Over 80% of respondents perceived some challenges to adoption of new randomization methods that may have more desirable properties. Over 80% of respondents identified opportunities for improving current practice, including education/training, development of standards/guidance on randomization, and adoption of validated software for generating randomization sequences. Conclusion: Practitioners acknowledge the pivotal role of randomization in trial results. There are some perceived challenges to successful implementation of randomization, and there are opportunities for improving practice.