Generation of allocation sequences in randomised trials: chance, not choice

Area of Science:

• Clinical Research Methodology
• Biostatistics

Background:

• Randomised controlled trials (RCTs) are the gold standard in clinical research.
• Randomisation, a key component of RCTs, is often poorly understood.
• Improper randomisation introduces selection and confounding biases, compromising study integrity.

Purpose of the Study:

• To emphasize the critical importance of proper randomisation in clinical trials.
• To advocate for the use of simple randomisation as the preferred method for bias prevention.
• To discuss alternative randomisation techniques and their implications for trial design.

Main Methods:

• Discusses simple (unrestricted) randomisation as the most basic and effective bias-prevention method.
• Examines restricted randomisation procedures like blocked and urn randomisation for managing sample size imbalances.
• Highlights the role of stratified randomisation in balancing allocation sequences within strata.

Main Results:

• Simple randomisation, though basic, is superior to complex methods in preventing bias.
• Restricted methods like blocked randomisation can help mitigate sample size imbalances.
• Effective randomisation, regardless of method, requires careful planning and execution.

Conclusions:

• Researchers must avoid non-random allocation methods to prevent bias.
• Simple randomisation should be used more frequently, accepting potential group size variations.
• Clear reporting of randomisation methods enhances scientific accuracy and credibility.