BRIGHT-HD—A Brazilian Research Investigation on Public Health Gains Comparing Survival Rates Between Hemodialysis and Hemodiafiltration: An Observational Study

Background/Objectives: High-flux online hemodiafiltration (OL-HDF) appears to be associated with better survival than hemodialysis (HD). In Brazil, OL-HDF is only affordable for patients with private health insurance. Although observational studies have shown a survival advantage with OL-HDF, even in Brazil, it is unclear whether this benefit applies to patients without private health insurance. We compared overall and cardiovascular mortality between OL-HDF and HD in patients treated exclusively through the public health care system. We hypothesized that patients on OL-HDF would have a higher survival rate than those on HD. Methods: This is an observational cohort study. Adult patients on maintenance hemodialysis or OL-HDF for at least one month during the period between 1 September 2022 and 1 December 2024 were enrolled into the study. The primary outcome was all-cause mortality. The secondary outcome was cardiovascular mortality. Fine-Gray sub-distribution hazard models were used to evaluate survival in the presence of competing events (kidney transplant and recovery of renal function). Results: Patients on HD (N = 321) and OL-HDF (N = 48) were similar in age, race, sex, and vascular access. Patients on HD were more likely to have diabetes (54.0% vs. 29.2%, p = 0.001) and spent more hours per week on dialysis (11.2 ± 1.8 vs. 10.5 ± 1.6 h, p = 0.006). In an adjusted Fine-Gray model, the hazard of death for patients on OL-HDF was 68% lower than that for patients on HD, and the risk of death for patients with an arteriovenous fistula was 55% lower compared to those with a catheter. Cardiovascular mortality did not differ between the groups. Conclusions: These findings suggest that OL-HDF is associated with an overall higher survival rate compared to HD, even for patients without private health insurance.