• Clinical investigations, in order to yield convincing results, must be planned so that they will involve comparisons between two groups alike in every respect excepting the one factor to be studied. The six unities recommended by Albritton should be observed; the two groups should be as nearly as possible alike as to time, place, materials, procedure, personnel, and attitudes. A report of the beneficial effects of any operation for peptic ulcer should have allowed a follow-up period of more than five years. Biliary intestinal anastomosis for stricture of the bile ducts that contract sufficiently well produces jaundice regardless of whether a biliary duodenal or a biliary jejunal anastomosis is made. New operations cannot be compared safely with old operations until enough years have elapsed to reveal delayed effects. Recent improvement in preoperative care, in anesthesia, and in the postoperative use of antibiotics, electrolytes, water, and blood transfusion give an apparent advantage to any new type of surgery. It is better to run series of older and newer types of operation contemporaneously (unity of time). Attention to the design of investigations is as important in surgery as in laboratory experimentation.
Walters W. SUITABLE CONTROLS IN SURGICAL INVESTIGATIONS. JAMA. 1957;163(1):25–29. doi:10.1001/jama.1957.02970360027006
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