Correspondence 5. Locatelli F, Mastrangelo F, Redaelli B, et al. Effects of different membranes and dialysis technologies on patient treatment tolerance and nutritional parameters. The Italian Cooperative Dialysis Study Group. Kidney Int. 1996;50:1293-1302. 6. Ronco C, Brendolan A, Lupi A, et al. Effects of a reduced inner diameter of hollow fibers in hemodialyzers. Kidney Int. 2000;58:809-817. Nistor et al declined to respond. Ó 2014 by the National Kidney Foundation, Inc. http://dx.doi.org/10.1053/j.ajkd.2014.03.024
absolute terms, convective therapy might [emphasis added] prevent 25 cardiovascular deaths for every 1000 patients treated for 1 year, but has no significant effect on death overall.”1(p962) Moreover, in our view, the decision to solicit unpublished data for the meta-analysis from 10 past trials—unavailable to the reader for scrutiny—is in itself a breach of scientific candor. Ultimately, like most meta-analyses, the review by Nistor et al1 is not without its own methodologic limitations, which not only impair informed decision making but also may suppress therapy modality innovations that increase quality of patient care.2 Sudhir K. Bowry, MSc, PhD Christian Apel, BSc, MSc Bernard Canaud, MD, PhD Fresenius Medical Care GmbH Bad Homburg, Germany
Assessment of Clinical Evidence for Convective Dialysis Therapies To the Editor: Evidence-based medicine is the cornerstone for informed decision making in health care and policy. We take issue with aspects of the recent systematic review by Nistor et al1 of convective versus diffusive dialysis therapies. More than one-third of the studies assessed by the authors could be deemed inappropriate in terms of size under good clinical trial practices: of the 35 studies, 13 included 15 or fewer patients and 1 included only 5. Further, 5 trials are pre-2000, one of which is from 1987, when hemodiafiltration was in its technological infancy. Inexplicably, the Convective Transport Study (CONTRAST) was adjudged as having the least risk of bias of all studies, yet there is no mention of a violation of study protocol (not achieving target convective dose, which is decisive in providing the survival advantage) in almost two-thirds of the hemodiafiltration arm of patients. From a statistical standpoint, relative risks of cardiovascular mortality and hypotension were reduced significantly with convective therapies, but the authors downplay these data: “In
820
Acknowledgements Financial Disclosure: The authors are employed by Fresenius Medical Care, which markets various dialysis therapy systems.
References 1. Nistor I, Palmer SC, Craig JC, et al. Convective versus diffusive dialysis therapies for chronic kidney failure: an updated systematic review of randomized controlled trials. Am J Kidney Dis. 2014;63(6):954-967. 2. Locatelli F. Comparison of hemodialysis, hemodiafiltration, and hemofiltration: systematic review or systematic error? Am J Kidney Dis. 2005;46(4):787-788. Nistor et al declined to respond. Ó 2014 by the National Kidney Foundation, Inc. http://dx.doi.org/10.1053/j.ajkd.2014.05.026
Am J Kidney Dis. 2014;64(5):817-820
absolute terms, convective therapy might [emphasis added] prevent 25 cardiovascular deaths for every 1000 patients treated for 1 year, but has no significant effect on death overall.”1(p962) Moreover, in our view, the decision to solicit unpublished data for the meta-analysis from 10 past trials—unavailable to the reader for scrutiny—is in itself a breach of scientific candor. Ultimately, like most meta-analyses, the review by Nistor et al1 is not without its own methodologic limitations, which not only impair informed decision making but also may suppress therapy modality innovations that increase quality of patient care.2 Sudhir K. Bowry, MSc, PhD Christian Apel, BSc, MSc Bernard Canaud, MD, PhD Fresenius Medical Care GmbH Bad Homburg, Germany
Assessment of Clinical Evidence for Convective Dialysis Therapies To the Editor: Evidence-based medicine is the cornerstone for informed decision making in health care and policy. We take issue with aspects of the recent systematic review by Nistor et al1 of convective versus diffusive dialysis therapies. More than one-third of the studies assessed by the authors could be deemed inappropriate in terms of size under good clinical trial practices: of the 35 studies, 13 included 15 or fewer patients and 1 included only 5. Further, 5 trials are pre-2000, one of which is from 1987, when hemodiafiltration was in its technological infancy. Inexplicably, the Convective Transport Study (CONTRAST) was adjudged as having the least risk of bias of all studies, yet there is no mention of a violation of study protocol (not achieving target convective dose, which is decisive in providing the survival advantage) in almost two-thirds of the hemodiafiltration arm of patients. From a statistical standpoint, relative risks of cardiovascular mortality and hypotension were reduced significantly with convective therapies, but the authors downplay these data: “In
820
Acknowledgements Financial Disclosure: The authors are employed by Fresenius Medical Care, which markets various dialysis therapy systems.
References 1. Nistor I, Palmer SC, Craig JC, et al. Convective versus diffusive dialysis therapies for chronic kidney failure: an updated systematic review of randomized controlled trials. Am J Kidney Dis. 2014;63(6):954-967. 2. Locatelli F. Comparison of hemodialysis, hemodiafiltration, and hemofiltration: systematic review or systematic error? Am J Kidney Dis. 2005;46(4):787-788. Nistor et al declined to respond. Ó 2014 by the National Kidney Foundation, Inc. http://dx.doi.org/10.1053/j.ajkd.2014.05.026
Am J Kidney Dis. 2014;64(5):817-820
