Overhydration, Cardiac Function and Survival in Hemodialysis Patients

Area of Science:

• Nephrology
• Cardiology
• Biomedical Engineering

Background:

• Chronic subclinical volume overload is common in hemodialysis (HD) patients.
• This condition is linked to hypertension, arterial stiffness, left ventricular hypertrophy, heart failure, and increased mortality.
• Assessing overhydration's impact on survival, independent of cardiac parameters, is crucial.

Purpose of the Study:

• To evaluate the association between bioimpedance-assessed overhydration and survival in HD patients.
• To determine if this relationship persists after adjusting for echocardiographic parameters.
• To propose and validate a new cut-off for relative fluid overload (RFO) for improved mortality prediction.

Main Methods:

• Prospective cohort trial involving 221 HD patients.
• Body composition assessed via bioimpedance at baseline.
• Echocardiography performed in 157 patients (subgroup).
• Survival analysis conducted using RFO cut-offs of 15% and a newly derived 17.4%.

Main Results:

• Overhydrated patients (both cut-offs) showed significantly increased all-cause mortality risk (univariate and multivariate).
• In the echocardiography subgroup, only the 17.4% RFO cut-off remained significantly associated with mortality after adjustments.
• Cardiovascular events were also significantly higher in overhydrated patients.

Conclusions:

• Hydration status independently predicts mortality risk in HD patients, irrespective of cardiac morphology and function.
• A new RFO cut-off of 17.4% is proposed for better definition of overhydration-related mortality risk.
• Further validation of this new cut-off in diverse HD populations is recommended.