Importance of normohydration for the long-term survival of haemodialysis patients

Background. Fluid overload and hypertension are among the most important risk factors for haemodialysis (HD) patients. The aim of this study was to analyse the impact of fluid overload for the survival of HD patients by using a selected reference population from Tassin. Methods. A positively selected HD population (n = 50) from Tassin (Lyon-France) was used as a reference for fluid status and all-cause mortality. This population was compared to one dialysis centre from Giessen (Germany) which was separated into a non-hyperhydrated (n = 123) and a hyperhydrated (n = 35) patient group. The hydration status (Delta HS) of all patients was objectively measured with whole-body bioimpedance spectroscopy in 2003. All-cause mortality was analysed after a 6.5-year follow-up. Results. Most of the reference patients from Tassin were normohydrated (Delta HS 0.25 +/- 1.15 L) at the start of the HD session. The hydration status of the Tassin patients was not different to the non-hyperhydrated Giessen patients (Delta HS 0.8 +/- 1.1 L) but significantly lower than in the hyperhydrated Giessen group (Delta HS 3.5 +/- 1.2 L). Multivariate adjusted all-causemortality was significantly increased in the hyperhydrated patient group (hazard ratio 3.41)-no difference in mortality could be observed between the Tassin and the non-hyperhydrated group from Giessen-even considering the fact that Tassin patients presented a significantly lower blood pressure. Conclusions. Fluid overload has a very high predictive value for all-cause mortality and seems to be one of the major killers in the HD population. Patients might strongly benefit from active management of fluid overload.