Clinical trials have served as the foundation of much of the knowledgewe have gained in the last 50 years with regard to the efficacy of treatmentsof various medical conditions. In very few conditions is the natural historyof the disease so well defined, and the outcome of intervention so evident,that the benefits as well as the adverse effects of a treatment can be determinedwithout a control group and randomization of treatment assignments. When atreatment dramatically alters the natural history of a disease, such as treatmentof pneumococcal pneumonia with penicillin, a randomized trial is not neededto judge efficacy; however, such examples are few and far between. Most treatmentsadministered in clinical medicine, even those that have been well evaluatedin clinical trials, produce modest or small beneficial effects.
Beck RW. Reporting the Results of Randomized Clinical TrialsA Priority of Archives of Ophthalmology. Arch Ophthalmol. 2004;122(7):1038-1039. doi:10.1001/archopht.122.7.1038