Optimization of the Convective Dose in On-Line Hemodiafiltration: Prospective Interventional Cohort Study—Conducted at Soissons Hospital, France

Background and Objectives: On-line hemodiafiltration (OL-HDF) has been proposed as an alternative to conventional hemodialysis (HD) for patients with end-stage chronic kidney disease (CKD). Randomized controlled trials suggest that OL-HDF may reduce mortality, particularly when the convection volume (CV) exceeds 23 L/1.73 m2 per session. However, achieving this target depends on local practices and may be limited to selected populations. The CONVINCE trial reported a 97% success rate using a structured optimization protocol, but its applicability to unselected real-world populations remains uncertain. This study aimed to evaluate the incidence of high CV in OL-HDF among unselected patients managed under routine conditions with a standardized optimization protocol. Methods and Materials: This prospective cohort study (May–October 2024) included 67 unselected incident and prevalent patients undergoing HD or HDF in a hospital-based dialysis center. All patients were switched to post-dilution OL-HDF following the CONVINCE optimization protocol, which involved stepwise increases in blood flow, adjustment of filtration fraction, and optimization of session duration. Results: The mean age was 68.8 ± 14.9 years; 56.7% were male. Blood flow increased from 283 to 338 mL/min (p < 0.001), and the use of dialyzers > 2 m2 increased from 36% to 68% (p < 0.003). Kt/V improved from 1.22 to 1.6 (p < 0.01). CV increased by ~2 L from M1 onward and was sustained through M6, correlating positively with blood flow, session duration, and Kt/V (all p < 0.01). Conclusions: Stepwise optimization protocol enabled sustained achievement of high CV (23.5 L/session) in 62.3% of patients, improving dialysis adequacy.