Even a Moderate Fluid Removal Rate during Individualised Haemodialysis Session Times Is Associated with Decreased Patient Survival.

BACKGROUND

Several studies report that fluid removal rate (FRR) above 10-13 mL/h/kg is associated with increased mortality in haemodialysis (HD) patients.

AIM

The aims of this study are to assess the influence of moderate FRR on survival in a cohort of prevalent dialysis patients with various dialysis session times and to challenge the FRR thresholds associated with increased mortality risk reported previously.

METHODS

Interdialytic weight gain (IDWG) and FRR (calculated from ultrafiltration [UF], target weight, and session time prescriptions) were studied in 190 prevalent dialysis patients (female: 42%, mean age: 69.5 years, median vintage: 40.2 months, diabetes: 34.7%, loop diuretic prescription: 5.8%) and averaged during the final quarter of 2010. Patient survival was analysed using Kaplan-Meier and Cox-multivariate analyses.

RESULTS

The median IDWG, median session time, and median FRR were 2.33 kg (-0.54-4.57), 5.0 h (3.9-8.0 h), 6.8 mL/h/kg (1.3-16.7), respectively, and FRR was ≥10 mL/h/kg in 11.6% of the patients. The Kaplan-Meier analysis showed decreased patient survival when the FRR was above the median (6.8 mL/h/kg; p = 0.012). The FRR was found to be independently associated with increased mortality (hazard ratio 1.15 [95% CI 1.02-1.29]; p = 0.027) using stepwise Cox proportional hazard regression analysis, including age, vintage, gender, body mass index (BMI), serum albumin level, β2-microglobulin level, cardiovascular and diabetes history, and session time. Online haemodiafiltration did not change this result. The role of residual renal function was unlikely because 74% of the patients had a vintage of >18 months, a minority (5.8%) were prescribed loop diuretics (a surrogate of significant urine output) and β2-microglobulin level was not different in patients who were below or above the FRR median.

CONCLUSION

We concluded that the FRR threshold above which there is an increased mortality is lower than what has been reported (7.8 mL/h/kg). It raises the question of the hazard of fluid removal and intermittence of standard HD.