B-type natriuretic peptide and interdialytic fluid retention are independent and incremental predictors of mortality in hemodialysis patients

Aim: Management of fluid homeostasis remains a major challenge in hemodialysis patients. We aimed to establish whether the cardiac strain marker B-type natriuretic peptide (BNP) could help to identify hypervolemic patients at increased risk of death. Methods: BNP levels were determined before dialysis in the entire I-ID population at our institution (n = 57). IDWG and BNP were stratified above or below 1.5 kg or the median value, respectively. All patients were prospectively followed for 35 months. The influence of IDWG and BNP on mortality was assessed with a Cox proportional hazards model, adjusted for each other, as well as for demographics, comorbidities, cardiac function, residual diuresis, dialysis duration and efficiency and complications of renal failure. Results: Median BNP was 303 (135 - 692) and 21(36%) patients displayed an average IDWG below 1.5 kg. During follow up a total of 25 (44%) patients died, 5 (26%) in the low IDWG group and 20 (53%) in the high IDWG group (adjusted hazard ratio (adjusted HR) 5.31 95% CI (1.47 - 19.1), p = 0.011). In the low BNP group 7 (25%) patients died and in the high BNP Group 18 (62%) patients died (adjusted HR 3.53 95 CI (1.37 - 9.09), p = 0.009). When both factors were considered simultaneously, patients with low BNP and low IDWG had an 11 times lower risk of death compared to patients with high BNP and high IDWG (HR. 0.08 95% CI (0.01 - 0.6129, p = 0.015). Conclusions: BNP and IDWG are independent and incremental predictors of mortality in HD patients. These findings suggest that BNP guided fluid management could improve survival in these patients.