ABSTRACT
A properly powered-controlled trial, if it included patients from only a single clinical site or center, would be challenged regarding its ability to capture suf‚ciently variable responses of patients with the disease de‚ned by their clinical phenotype due to site-to-site or center-to-center variability. Baseline factors that are prognostic of disease, such as age, gender, race/ethnicity, and disease severity, are important factors for trial design consideration. This is because variability is the law of life, and as no two faces are the same, so no two bodies are alike, and no two individuals react alike, or behave alike under the abnormal conditions we know as disease (Sir William Osler, 1849-1919). Single-center controlled trials are therefore discouraged as the sole basis for providing substantial and persuasive evidence to conclude that treatment would be effective for the indication sought.
