Dialysis patients exhibit an inverse, L- or U-shaped association between blood pressure and mortality risk, in contrast to the linear association in the general population. We prospectively studied 9333 hemodialysis patients in France, aiming to analyze associations between predialysis systolic, diastolic, and pulse pressure with all-cause mortality, cardiovascular mortality, and nonfatal cardiovascular endpoints for a median follow-up of 548 days. Blood pressure components were tested against outcomes in time-varying covariate linear and fractional polynomial Cox models. Changes throughout follow-up were analyzed with a joint model including both the time-varying covariate of sequential blood pressure and its slope over time. A U-shaped association of systolic blood pressure was found with all-cause mortality and of both systolic and diastolic blood pressure with cardiovascular mortality. There was an L-shaped association of diastolic blood pressure with all-cause mortality. The lowest hazard ratio of all-cause mortality was observed for a systolic blood pressure of 165 mm Hg, and of cardiovascular mortality for systolic/diastolic pressures of 157/90 mm Hg, substantially higher than currently recommended values for the general population. The 95% lower confidence interval was approximately 135/70 mm Hg. We found no significant correlation for either systolic, diastolic, or pulse pressure with myocardial infarction or nontraumatic amputations, but there were significant positive associations between systolic and pulse pressure with stroke (per 10-mm Hg increase: hazard ratios 1.15, 95% confidence interval 1.07 and 1.23; and 1.20, 1.11 and 1.31, respectively). Thus, whereas high pre-dialysis blood pressure is associated with stroke risk, low pre-dialysis blood pressure may be both harmful and a proxy for comorbid conditions leading to premature death.
Background
Fluid overload is frequent among hemodialysis (HD) patients. Dialysis therapy itself may favor sodium imbalance from sodium dialysate prescription. As on-line hemodiafiltration (OL-HDF) requires large amounts of dialysate infusion, this technique can expose to fluid accumulation in case of a positive sodium gradient between dialysate and plasma. To evaluate this risk, we have analyzed and compared the fluid status of patients treated with HD or OL-HDF in French NephroCare centers.
Method
This is a cross-sectional and retrospective analysis of prevalent dialysis patients. Data were extracted from the EUCLID5 data base. Patients were split in 2 groups (HD and OL-HDF) and compared as whole group or matched patients for fluid status criteria including predialysis relative fluid overload (RelFO%) status from the BCM®.
Results
2242 patients (age 71 years; female: 39%; vintage: 38 months; Charlson index: 6) were studied. 58% of the cohort were prescribed post-dilution OL-HDF. Comparing the HD and OL-HDF groups, there was no difference between HD and OL-HDF patients regarding the predialysis systolic BP, the interdialytic weight gain, the dialysate-plasma sodium gradient, and the predialysis RelFO%. The stepwise logistic regression did not find dialysis modality (HD or OL-HDF) associated with fluid overload or high predialysis systolic blood pressure. In OL-HDF patients, monthly average convective or weekly infusion volumes per session were not related with the presence of fluid overload.
Conclusions
In this cross-sectional study we did not find association between the use of post-dilution OL-HDF and markers of fluid volume excess. Aligned dialysis fluid sodium concentrations to patient predialysis plasma sodium and regular monitoring of fluid volume status by bioimpedance spectroscopy may have been helpful to manage adequately the fluid status in both OL-HDF and HD patients.
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