Re: A Randomized, Prospective Comparison of the Tesio, Ash Split, and Opti-Flow Hemodialysis Catheters

Editor: I read with interest the paper entitled “A Randomized, Prospective Comparison of the Tesio, Ash Split, and OptiFlow Hemodialysis Catheters” published recently in JVIR by Richard et al (1). The authors are to be commended on their effort to make sense of the many catheters available today. However, I find substantial fault with the methodology of the paper, which is sufficiently alarming to prompt this letter. Specifically, the authors have entitled their paper a “prospective, randomized” comparison. However, nowhere in the manuscript is there any description of a sample size calculation, although one would be mandatory for a study of this nature. Randomization by day of procedure in a defined, rotating order is an unacceptable technique; the operators obviously knew exactly what type of catheter would be placed on a given day and could significantly influence the choice of catheter by scheduling patients accordingly, as could any referring nephrologist who knew the study was underway. This is a basic tenet of scientific research, and any Institutional Review Board (IRB) reviewing the study would have pointed this out, as well as required a sample size calculation for a “prospective, randomized” study. This brings me to the most important point: the authors do not indicate that Institutional Review Board approval was granted for this study. If this is an oversight, it is a very significant one worthy of a published erratum in JVIR. If not, and the authors truly did not have IRB approval to perform a randomized human study, then this is a direct violation of all ethical standards of medical research as well as the Helsinki declaration (2) and could readily subject all of the authors to significant sanctions. If this study was not IRBapproved, there is no place for it in the pages of JVIR, and a complete retraction should be published. There are other methodologic flaws in the study, including an interesting definition of “Qb eff,” which appears to be an inaccurate attempt to replicate a definition used in a study we published recently in JVIR (3). The definition refers to the effective flow rate determined at a given dialysis pump speed (Qb) using ultrasonic dilution technique (Transonic, Ithaca, NY). This technique has become the standard of reference in evaluating catheters but the authors chose not to use it, relying instead on the less accurate measure of mean pump speed during dialysis. The use of the term “Qb eff” could easily mislead a reader to think that the more accurate technique was used. This should be published as an erratum. Radiology organizations continue to lament the lack of research in radiology, but no research at all would be better than studies which violate basic protection principles for human beings. If we as a specialty wish to have our work perceived by other specialties as worthy of their interest, we must adhere to these principles and strive to perform studies that will stand up to scientific and public scrutiny. References 1. Richard HM, Hastings GS, Boyd-Kranis RL, et al. A randomized, prospective evaluation of the Tesio, Ash Split, and Optiflow hemodialysis catheters. J Vasc Interv Radiol 2001; 12:431– 435. 2. Ethical Principles for Medical Research Involving Human Subjects. World Medical Association Declaration of Helsinki, June 1964 and subsequent amendments. Available at: http://www. wma.net/e/policy/17-c_e.html. Accessed June 4, 2001. 3. Trerotola SO, Shah H, Johnson MS, et al. Randomized comparison of high-flow versus conventional hemodialysis catheters. J Vasc Interv Radiol 1999; 10:1032–1038.