Although these initial papers studied intervention they had no control groups or did not use groups of patients receiving placebos as control groups necessary in the absence of prior evidence of the effectiveness of the intervention, or they were not double blind studies.
Estos estudios iníciales, pese a ser de intervención, carecían de grupo control, o no incluyeron grupo placebo como control era necesario ante la ausencia de evidencia previa de la eficacia de la intervención o no fueron doble ciego.