Introduction to a generalized method for adaptive randomization in trials

BACKGROUND Ideally clinical trials should use some form of randomization for allocating participants to the treatment groups under trial. As an integral part of the process of assessing the effectiveness of these treatment groups, randomization performed well can reduce, if not eliminate, some forms of bias that can be evident in non-randomized trials. Given the vast set of possible randomization methods to choose from we demonstrate a method that incorporates many of the advantages of these other methods. METHODS A step-by-step introduction of how to use the adaptive randomization algorithm for conducting a clinical trial is given. RESULTS The implications, effects and capabilities of using the adaptive randomization algorithm are fully demonstrated and explained using simulated data and examples from actual trials. CONCLUSIONS This paper provides an introduction to a dynamic type of treatment allocation, which fulfills the CONSORT requirements of participants being randomly allocated whilst maintaining a level of control of the balances overall, within the stratification variables and within the strata simultaneously. Maintaining control of the imbalances within the groups is vital particularly if interim analyses are planned. TRIAL REGISTRATION Current controlled trials ISRCTN17551624, ISRCTN37558856, ISRCTN97185214.