Comparing Two Hemodialysis Systems in Adults Receiving Dialysis Twice a Week in Yogyakarta, Indonesia

This prospective, single-center, nonrandomized study enrolled adults aged 18 to 75 years who had received maintenance hemodialysis for at least three months at Bethesda Hospital in Yogyakarta, Indonesia. All participants followed a twice-weekly dialysis schedule and had arteriovenous fistula access. Each participant was scheduled for four sessions over two weeks. The first two sessions used the Robust RB-KRC-HMD-U01 machine with the WOLFGANG HD18M dialyzer. The next two used the Nikkiso DBB-EXA ES machine with the Purifier H180 dialyzer. Within each participant, prescribed treatment duration, blood flow rate, and dialysate flow rate were matched across periods. Ultrafiltration was individualized according to clinical need. Both the machine and dialyzer changed between periods, and all participants received the systems in the same order without a washout. The design therefore compared the two complete systems and could not separate their effects from treatment order or distinguish the contribution of the machine from that of the dialyzer. The primary outcome was per-session single-pool Kt/V (spKt/V), a measure of urea-based dialysis dose calculated using the second-generation Daugirdas equation. The two session values were averaged within each participant and treatment period. The planned noninferiority comparison used the paired difference in spKt/V, calculated as new system minus established system, with a prespecified margin of -0.15. Other assessments included the per-session urea reduction ratio, serum chemistry, blood counts, blood pressure, body weight, and achieved ultrafiltration. For the exploratory beta-2-microglobulin outcome, the intended sampling times were immediately before the first session and immediately after the second session of each period. The difference between these concentrations represented the change over two sessions. Adverse events were documented during the study, and serious adverse events were summarized according to the system each participant had received.