Randomized control trials – RCTs – rose to prominence in the twentieth century as physicians and regulators sought to evaluate rigorously the performance of new medical therapies; by century’s end, RCTs had become, as medical historian Laura Bothwell has noted, “the gold standard of medical knowledge,” occupying the top position of the “methodologic heirarch[y].”
The value of RCTs lies in the random, generally blinded, allocation of patients to treatment or control group, an approach that when properly executed minimizes confounders (based on the presumption that any significant confounder would be randomly allocated as well), and enables researchers to discern the efficacy of the intervention (does it work better – or worse – than controls) and begin to evaluate the safety and side-effects.
The power and value of RCTs can be seen with particular clarity in the case of proposed interventions that made so much intuitive sense (at the time) that it seemed questionable, perhaps even immoral, to conduct a study. Examples include use of a particular antiarrhythmic after heart attacks (seemed sensible, but actually caused harm); and use of bone marrow transplants for metastatic breast cancer (study viewed by many as unethical yet revealed no benefit to a procedure associated with significant morbidity).
In these and many other examples, a well-conducted RCT changed clinical practice by delivering a more robust assessment of an emerging technology than instinct and intuition could provide.