Clinical Kidney Journal, 2018, vol. 11, no. 3, 370–371 doi: 10.1093/ckj/sfy021 Advance Access Publication Date: 2 April 2018 Editorial Comment EDITORIAL COMMENT Is relative overhydration measurement by bioimpedance spectroscopy useful in reducing morbidity and mortality in chronic kidney disease? 1 2 3 Doruk C. Karaaslan , Baris Afsar and Mehmet Kanbay 1 2 Department of Medicine, Koc University School of Medicine, Istanbul, Turkey, Department of Nephrology, Suleyman Demirel University School of Medicine, Isparta, Turkey and Department of Medicine, Division of Nephrology, Koc University School of Medicine, Istanbul, Turkey Correspondence and offprint requests to: Mehmet Kanbay; E-mail: firstname.lastname@example.org ABSTRACT It is well known that one of the main determinants of mortality and morbidity in chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients is ﬂuid overload acting on the cardiovascular system causing hypertension, increased arterial stiffness, left ventricular hypertrophy and eventually heart failure. Therefore, assessment and management of volume status is crucial. Bioimpedance spectroscopy is one of the most popular and practical methods for volume evaluation. Volume evaluation should be a routine part of following CKD and ESRD patients, in order to decrease associated mortality and morbidity. Keywords: bioimpedance spectroscopy, cardiovascular disease, kidney disease, volume evaluation One of the main determinants of mortality and morbidity in in Stages 4and 5CKD (ESRD) patients whodonot receive haemo- chronic kidney disease (CKD) end-stage renal disease (ESRD) pa- dialysis in their recent prospective study . Their research con- tients is fluid overload. Fluid overload acts on the cardiovascu- sists of 356 patients with a median follow-up of 50 (24–66) months. lar system causing hypertension, increased arterial stiffness, They collected demographic and clinical data of the patients left ventricular hypertrophy and eventually heart failure [1–4]. including cardiovascular comorbidities and diuretics usage rate, Thus to decrease cardiovascular risk among ESRD patients, which was 43% among the patients. Only non-haemodialysis pa- finding a sensitive specific and practical method to detect fluid tients were included at the beginning of the study yet the authors overload is highly crucial. Many modalities assessing fluid over- reported that 125 patients (35%) required haemodialysis during load are available, such as visualizing B lines on lung ultrason- their study. They stated that mean relative OH was 2.3 6 0.8%. The ography, bioimpedance spectroscopy, echocardiography and authors divided the study population into two, those whose rela- clinical judgment. More sophisticated methods such as com- tive OH exceed 0% and those whose do not. The result was the puted tomography and magnetic resonance imaging are also increased mortality in the patients with> 0%. The authors con- available, but they are costly and impractical for daily practice. cluded that bioimpedance is a valuable method to follow up not Bioimpedance spectroscopy, however, is becoming popular only haemodialysis patients but also non-haemodialysis ESRD since it is practical and economical . patients to decrease cardiovascular morbidity and mortality. Vega et al. discuss whether relative overhydration (overhydra- Fluid OH monitoring by bioimpedance spectroscopy has tion (OH)/extracellular water) causes more mortality and morbidity gained attention in recent years, and Vega et al. investigate if Received: 25.2.2018. Editorial decision: 27.2.2018 V C The Author(s) 2018. Published by Oxford University Press on behalf of ERA-EDTA. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact email@example.com Downloaded from https://academic.oup.com/ckj/article-abstract/11/3/370/4958781 by Ed 'DeepDyve' Gillespie user on 20 June 2018 Hypervolaemia in CKD | 371 this method predicts mortality and morbidity in non-dialytic electrolyte balances . Discussing whether assessing fluid OH ERSD patients. The effectness of the bioimpedance method has of the patients regularly by bioimpedance spectroscopy would been assessed in haemodialysis patients before [6–8], yet this be of benefit in terms of preserving the residual renal function article is the first in the field as it discusses the same method in might be investigated in a similar study population in the non-haemodialysis patients. Furthermore, the strength of this future. study comes from the large number of participants. In addition, Overall, Vega et al. present new evidence about the success of the duration of the follow-up, which is a median of 50 months, bioimpedance spectroscopy in predicting the mortality and mor- increases the credibility. bidity of non-haemodialysis ESRD patients by assessing the rela- The manuscript opens new questions and stimulates further tive fluid OH . The article offers a sufficient amount of patients research. There are also interesting findings that are not dir- followed for a reasonable period. Periodical measuring of the rela- ectly predictable. First, as also discussed by the authors, bioim- tive OH is lacking, and the question of whether this method is pedance recordings were only noted at the beginning of the useful in clinical practice is left unanswered. The hypotheses of study. Assessing whether measuring relative OH in regular whether periodical follow-up with bioimpedance spectroscopy check-ups (e.g. monthly) increases morbidity in ESRD patients would predict residual renal function and how differences in di- and thus helps to arrange renal replacement therapy might be uretic types and dosages affect the results of relative OH in non- studied as well. Studying such a hypothesis may yield more haemodialysis ESRD patients would be worth investigating in fu- solid evidence about the usefulness of this method in daily ture studies. practice. Moreover, recording sodium and water intake and urine output, and how these variables affect relative OH meas- ured by bioimpedance spectroscopy, would be valuable in terms REFERENCES of accuracy of OH risk estimation. This might be achieved by 1. Tonelli M, Wiebe N, Culleton B et al. Chronic kidney disease regular clinical check-ups, recording mean values and taking and mortality risk: a systematic review. J Am Soc Nephrol 2006; them into account. Secondly, it is interesting to note that mor- 17: 2034–2047 tality predictors and cardiovascular event predictors are differ- 2. Ortiz A, Covic A, Fliser D et al. Epidemiology, contributors to, ent. Proteinuria, C-reactive protein, impaired kidney function and clinical trials of mortality risk in chronic kidney failure. and previous cardiovascular events are predictors of cardiovas- Lancet 2014; 383: 1831–1843 cular events , whereas, an independent association with mor- 3. Onofriescu M, Siriopol D, Voroneanu L et al. Overhydration, tality and age, Charlson index, higher C-reactive protein levels, cardiac function and survival in hemodialysis patients. PLoS low lean tissue index and relative OH was observed. It would be One 2015; 10: e0135691 better to comment on this finding and discuss why OH was 4. Ekinci C, Karabork M, Siriopol D et al. Effects of volume over- associated with total mortality but not with cardiovascular load and current techniques for the assessment of ﬂuid status events. It is also worth mentioning whether N-terminal prohor- in patients with renal disease. Blood Purif 2018; (in press) mone of brain natriuretic peptide was associated with fluid 5. Vega A, Abad S, Macı´as N et al. Any grade of relative overhy- overload. Thirdly, the authors reported that 125 patients (35%) dration is associated with long-term mortality in patients required haemodialysis during their study . However, they with Stage 4 and 5 non-dialysis chronic kidney diesase. 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Clinical Kidney Journal – Oxford University Press
Published: Apr 2, 2018
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