Historical control

In clinical research, randomized control trials (RCTs) are the best form of a clinical study to provide the most reliable evidence on the effectiveness of intervention/treatment. But there are circumstances where RCTs are not feasible or unethical to conduct, for example, in the case of rare diseases and difficult experimental circumstances, then data from previous studies are used as a control group (historical controls) for the clinical study. Historical controls are known as a type of control arm for single-arm trials and incorporating historical data in single-arm trials accelerates drug development, though this may introduce some bias. The main objective of this chapter is to throw light on the historical controls, definition, selection, uses, study design, and approaches to eliminate biases in historical controls.