Most of the medical practice has not been proven by controlled clinical trials, and there are no plans to conduct such trials in order to decrease clinician uncertainty. This happens partly due to the difficulty of making designs with scientific and ethical validity, the costs of this type of research and the time required to generate results, which can be several years. Clinical trials do not have the capability to generate information that allows to make decisions in some sectors of clinical care and public health, such as when an epidemic occurs. Therefore, medical science is based on observational studies, past practices and therapeutic tradition (1). Observation of clinical data that have defined a clinical behavior precedes the clinical trial. The knowledge about scurvy, the fact that this pathology is considered a nutritional deficiency and its treatment with citrus fruits, originated thanks to the collection of clinical data on sailors, soldiers and prisoners of the British Crown in the 18th and 19th centuries (2). This clinical information, which was collected uniformly and served to produce new knowledge, is what is now known as Real World Data (RWD). A modern definition of RWD would be one that talks about data obtained by any non-interventionist methodology that is collected prospectively and retrospectively from observations of routine clinical practice, and which comes from various sources including data from patients, doctors, hospitals, payers, social data, etc (3).