NDT Advance Access originally published online on June 20, 2008
Nephrology Dialysis Transplantation 2008 23(9):3035; doi:10.1093/ndt/gfn329
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Reply
E-mail: vincenzo.panichi{at}med.unipi.itSir,
We received the letter of Penne and associates regarding our recent observational, prospective RISCAVID (RISchio CArdiovascolare nei pazienti afferenti all’Area Vasta In Dialisi) study [1].
As we stated in our paper, our foremost intention was to show the link between systemic inflammation and mortality in the whole population. Indeed, the highest levels of CRP and inflammatory cytokines associated with low serum albumin values were strong outcome predictors in haemodialysis (HD) patients, supporting the hypothesis that chronic inflammation is an important risk factor for cardiovascular (CV) and overall mortality in this population. We acknowledge the fact that the published protocol of the Dutch CONvective TRAnsport STudy (CONTRAST) controlled trial is directed at evaluating the impact of different convection therapies on CV disease such as left ventricular hypertrophy, and vessel wall parameters [2]. Regarding the Kt/V, however, our Kt/V that were not dissimilar between the two different modalities are reminiscent to those recently published by Carracedo et al. [3], who performed a double cross-over randomized clinical study on high-flux HD versus online haemodiafiltration (HDF). This brings up an important point. Despite similar Kt/V (which are already in their high range of >1.4), online HDF still features as a superior technique. Beta-2 microglobulin (b2-m) clearance or pre-dialysis b2-m levels were not shown, since we had not deliberatively considered it of value. As explained in the paper, our study had the advantage of being performed on a prevalent population relatively homogeneous for race, geography, medical care and HD management. Therefore, enhanced clearance of middle molecules was inherent to the homogeneity of our study population and clinical monitoring of the available data. This would, however, be a requirement for a randomized clinical trial.
We have stressed the limitations of any observational study and the possible biases inherent to it. Nevertheless, the difference in mortality between high-flux and online HDF was striking and well in agreement with previous data from the DOPPS study [4] and the EUCLID database [5]. We have also well clarified that
in respect to the DOPPS, the RISCAVID population differed from other existing studies for the high incidence of mixed convective-diffusive techniques (HDF 44% of the entire population). This equalled to 333 patients being followed for thirty months in respect to the 89 over 443 Italian patients of the DOPPS study (35). Of interest in our study, the difference in cumulative survival started after fifteen months of observation after adjustment for age, dialysis vintage and co-morbidities. At variance with the paper with Canaud [4], we were not able to establish a relationship between mortality and volume exchange. Despite this limitation, HDF using sterile bags is customarily prescribed using 10–15 L/session of reinfusion fluid while on-line HDF is performed with at least 22–25 L/session.
We hope we have helped to clarify the issues raised by the letter of Penne et al. whom we thank for their appreciation and criticisms.
Conflict of interest statement. Ciro Tetta is fully employed by Fresenius Medical Care.
1 Internal Medicine Department, Nephrology Section, via roma 67, Pisa, 56100, Italy 2 Fresenius Medical Care, Deutschland GmbH DaimelerStrassse 15, D-61352 Bad Homburg, 61352, Germany
References
- Panichi V, Rizza GM, Paoletti S, et al, on behalf of the RISCAVID Study Group. Chronic inflammation and mortality in haemodialysis: effect of different renal replacement therapies. Results from the RISCAVID study. Nephrol Dial Transplant (2008) Feb 27 [Epub ahead of print] da completare.
- Penne EL, Blankestijn PJ, Bots ML, et al. Effect of increased convective clearance by on-line hemodiafiltration on all cause and cardiovascular mortality in chronic hemodialysis patients—the Dutch CONvective TRAnsport STudy (CONTRAST): rationale and design of a randomised controlled trial [ISRCTN38365125]. Curr Control Trials Cardiovasc Med (2005) 6:8.[CrossRef][Medline]
- Carracedo J, Merino A, Nogueras S, et al. On-line hemodiafiltration reduces the proinflammatory CD14+ CD16+ monocyte-derived dendritic cells: a prospective, crossover study. J Am Soc Nephrol (2006) 17:2315–2321. (Epub 6 July 2006).
[Abstract/Free Full Text] - Canaud B, Bragg-Gresham JL, Marshall MR, et al. Mortality risk for patients receiving hemodiafiltration versus hemodialysis: European results from the DOPPS. Kidney Int (2006) 69:2087–2093.[CrossRef][Web of Science][Medline]
- Jirka T, Cesare S, Di BA, et al. Mortality risk for patients receiving hemodiafiltration versus hemodialysis. Kidney Int (2006) 70:1524–1525.[Web of Science][Medline]
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