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Mr Adiseshiah questions our use of the term “clinical trial” and suggests that “case control study” better describes our study.

A clinical trial is a research activity that involves the administration of a test treatment to humans to evaluate the treatment. The term clinical trial is subject to a wide variation in usage. In some cases, it may refer to the first use of a new treatment without any control treatment. In other cases, it may refer to a designed investigation that involves a test and a control treatment, in which case it is called a controlled clinical trial. Rigorously designed investigations that involve randomization of test and control treatments are called randomized controlled clinical trials.¹

In our study, the test treatment was a new medical device, the AneuRx stent graft, used to treat aortic aneurysms in humans. The investigational design included a prospective control group and included 12 clinical sites. Thus, the description of a “multicenter, prospective controlled clinical trial,” we believe, is accurate.

A case control study is generally used for epidemiologic research and involves the identification of persons with the disease of interest (cases) and a suitable group of persons without the disease of interest (controls). Cases and controls are compared with respect to some existing or past attribute or exposure believed to be causally related to the disease. Case control studies are referred to as retrospective studies because the research approach proceeds from effect to cause, even if the data are accumulated in a prospective manner.¹ This term would not have been appropriate for our study.

Although some investigators believe that new medical treatments should be introduced only if supported with data from prospective randomized controlled clinical trials, this is not necessarily the case. Few would argue that we need a prospective randomized trial to determine whether medical or surgical therapy should be carried out for patients with large aortic aneurysms. Our nonrandomized controlled trial results clearly showed the early benefits of endovascular aneurysm repair with reduced blood loss, reduced need for blood transfusion, reduced intensive care unit time, reduced hospital stay, and earlier return to function as compared with open surgical repair. Patients readily recognize the benefits of this less morbid procedure.

The unknown question in the area of endovascular repair is the long-term effectiveness of the procedure. The answers to these questions will necessitate long-term follow-up of patients with endovascular grafts and patients who undergo open surgical repair in controlled clinical trials, such as ours. There is reason to doubt that prospective randomization will be of major benefit in the evaluation of the ultimate role of this technology, given the wide variability in aneurysm size and morphology, patient comorbidities precluding randomization, and continually improving technology of stent graft design and delivery. The most clinically useful and effective treatments in surgical practice are in place, not as a result of prospective randomized trials, but as a result of well-designed, carefully controlled clinical trials and precise long-term follow-up in evaluating results.

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References 

1. Meinert CL. Clinical trials, design, conduct, and analysis. In: New York: Oxford University Press; 1986;p. 283–284
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