Dialysis Fluid Endotoxin Level and Mortality in Maintenance Hemodialysis: a Nationwide Cohort Study

Background: The quality of dialysis fluid water might play an important role in hemodialysis patient outcomes. Although targeted endotoxin levels of dialysis fluid vary among countries, evidence of the contribution of these levels to mortality in hemodialysis patients is lacking.

Study Design: Retrospective cohort study using data from the Japan Renal Data Registry, a nationwide annual survey.

Setting & Participants: 130,781 patients receiving thrice-weekly in-center hemodialysis for more than 6 months were enrolled at 2,746 facilities in Japan at the end of 2006. None of the patients changed facility or treatment modality during 2007.

Predictor: Highest endotoxin level in dialysis fluid reported by each facility during 2006. Patients were categorized by facility endotoxin level into the following groups: <0.001, 0.001 to <0.01, 0.01 to <0.05, 0.05 to <0.1, and ≥0.1EU/mL. Age, sex, dialysis vintage, diabetes mellitus as a primary cause of end-stage renal disease, Kt/V, normalized protein catabolic rate, dialysis session duration, serum albumin, and hemoglobin were measured as potential confounders.

Outcome: All-cause mortality, censored by transplantation; withdrawal from dialysis treatment; or end of follow-up.

Results: Of 130,781 hemodialysis patients, 91.2% had facility endotoxin levels below the limit set for dialysis fluid in Japan (<0.05EU/mL). During a 1-year follow-up, 8,978 (6.9%) patients died of all causes. The rate of all-cause mortality at 1 year was highest in the ≥0.1-EU/mL category (88.0 deaths/1,000 person-years). Patients in the ≥0.1-EU/mL group exhibited an increased risk of all-cause mortality of 28% (95% CI, 10%-48%) compared to the <0.001-EU/mL group.

Limitations: Endotoxin level in dialysis fluid is reported as categorical data. No information about variation in endotoxin levels in dialysis fluid over time.

Conclusions: Higher facility endotoxin levels in dialysis fluid may be related to increased risk for all-cause mortality among hemodialysis patients. Correcting this modifiable facility water management practice might improve the outcome of hemodialysis patients.