Overhydration, Cardiac Function and Survival in Hemodialysis Patients

Abstract

Background and objectivesChronic subclinical volume overload occurs very frequently and may be ubiquitous in hemodialysis (HD) patients receiving the standard thrice-weekly treatment. It is directly associated with hypertension, increased arterial stiffness, left ventricular hipertrophy, heart failure, and eventually, higher mortality and morbidity. We aimed to assess for the first time if the relationship between bioimpedance assessed overhydration and survival is maintained when adjustments for echocardiographic parameters are considered.Design, setting, participants and measurementsA prospective cohort trial was conducted to investigate the impact of overhydration on all cause mortality and cardiovascular events (CVE), by using a previously reported cut-off value for overhydration and also investigating a new cut-off value derived from our analysis of this specific cohort. The body composition of 221 HD patients from a single center was assessed at baseline using bioimpedance. In 157 patients supplemental echocardiography was performed (echocardiography subgroup). Comparative survival analysis was performed using two cut-off points for relative fluid overload (RFO): 15% and 17.4% (a value determined by statistical analysis to have the best predictive value for mortality in our cohort).ResultsIn the entire study population, patients considered overhydrated (using both cut-offs) had a significant increased risk for all-cause mortality in both univariate (HR = 2.12, 95%CI = 1.30–3.47 for RFO>15% and HR = 2.86, 95%CI = 1.72–4.78 for RFO>17.4%, respectively) and multivariate (HR = 1.87, 95%CI = 1.12–3.13 for RFO>15% and HR = 2.72, 95%CI = 1.60–4.63 for RFO>17.4%, respectively) Cox survival analysis. In the echocardiography subgroup, only the 17.4% cut-off remained associated with the outcome after adjustment for different echocardiographic parameters in the multivariate survival analysis. The number of CVE was significantly higher in overhydrated patients in both univariate (HR = 2.46, 95%CI = 1.56–3.87 for RFO >15% and HR = 3.67, 95%CI = 2.29–5.89 for RFO >17.4%) and multivariate (HR = 2.31, 95%CI = 1.42–3.77 for RFO >15% and HR = 4.17, 95%CI = 2.48–7.02 for RFO >17.4%) Cox regression analysis.ConclusionsThe study shows that the hydration status is associated with the mortality risk in a HD population, independently of cardiac morphology and function. We also describe and propose a new cut-off for RFO, in order to better define the relationship between overhydration and mortality risk. Further studies are needed to properly validate this new cut-off in other HD populations.

Multiple-frequency bioimpedance devices for fluid management in people with chronic kidney disease receiving dialysis: a systematic review and economic evaluation

“…A total of five RCTs (published in six papers 60,61,63,76,77,81 ) and eight non-randomised studies (published in nine papers 30,50,[82][83][84][85][86][87][88] ) were included in the review of clinical effectiveness. There was some question over whether or not the RCTs by Onofriescu et al 81 and Onofriescu et al 60 may be reporting the same trial or outcomes from an overlapping patient population.…”

“…The eight non-randomised studies were reported in nine full-text papers, 30,50,[82][83][84][85][86][87][88] with the study by O'Lone et al 82 also reported in a secondary study with an additional 51 participants and a 21-month longer follow-up period. 84 The BCM was the multiple-frequency device used in all eight studies.…”

“…30 Three studies were multicentred 30,85,86 and the remaining five studies were conducted in single dialysis centres. 50,82,83,87,88 Six studies involved patients receiving HD 30,50,[85][86][87][88] and the remaining two studies involved solely patients treated with PD. 82,83 The length of follow-up in the eight non-randomised studies ranged from 16 weeks 85 to 3.5 years.…”

“…30,50,82,83,[85][86][87][88] The studies were of two main types: in some studies, the BCM was used to classify patients into groups (e.g. overhydrated/non-overhydrated) and then outcomes were compared across the groups; 30,88 and in other studies, the BCM was used as a basis for adjustment of dry weight 50,82,85,86 or to obtain hydration parameters. 83,87 Six cohort studies reported the mean age of participants, which ranged from 53.…”

The Relationship Between Bioimpedance-Measured Volume and Nutritional Parameters and Mortality in Hemodialysis Patients

“…Moving patients into the normohydration target range leads to a better control of hypertension (38,39), fewer intradialytic adverse events and improved cardiac function (38,40). Recently Onofriescu et al prospectively conducted a study to investigate the impact of hydration status measured by BCM to all cause mortality and found that the hydration status was associated with the mortality risk in a HD population, independently of cardiac morphology and function (41). In the present study, we found that the proportion of hypervolemic patients evaluated by either clinical, laboratory or bioimpedance methods was significantly higher in the dead group and hypervolemia was an independent risk factor for mortality.…”