Abstract
Background and Aims
Incremental HD is a method of individualising haemodialysis (HD) dose according to level of residual renal function(RRF) such that as RRF reduces, HD dose is upwardly adjusted. Retrospective data suggest potential benefit of this approach in preserving RRF, a key predictor of survival for dialysis patients.
Method
A randomised, intention-to-treat, multi-centre trial was designed to determine the feasibility of a future definitive trial of incremental HD to establish if this approach preserves RRF. The trial was designed to estimate effect size of potential benefit in terms of RRF.
55 patients with RRF urea clearance≥3ml/min/1.73m2 BSA and within 3 months of starting HD were randomised across 4 UK dialysis centres to either conventional 3x weekly HD for 3.5-4 hours or incremental HD. The incremental HD protocol involved initiation of HD 2x weekly after randomization and upward adjustment of HD frequency and time as RRF was lost.
In the conventional HD arm, patients were dialysed to ensure Standard Kt/VDialysis>2.0. In the incremental HD arm, patients were dialysed to ensure Standard Kt/VDialysis+Standard Kt/VResidual Renal Function>2.0 so both groups were dialysed to the same urea clearance target, except that urea clearance incorporated RRF in the incremental HD arm. Follow up was for 6 months (primary outcome data) but secondary outcome data will be for 12m. Patients were withdrawn for transplant, dialysis modality change or for patient choice.
The primary outcome was rate of change of RRF in the first 6 months after randomization (effect size of intervention). Recruitability, retainability, protocol adherence and rate of adverse events were also measured as a primary objective. As a secondary outcome, we determined proportion of patients with urea clearance≥2 and ≥3ml/min /1.73m2 BSA at the 6 month time point. Impact of dialysis treatment was measured using questionnaire-based assessments at baseline and 6 months.
Results
26 patients were randomised to standard HD and 29 to incremental HD. Baseline demographics including age, weight, haemoglobin, blood pressure, Charleson Comorbidity Index, were not significantly different between study arms. Baseline residual renal urea clearance was 5.1 ± SD 1.8 ml/min/1.73m2 BSA in the standard HD arm and 5.72 ± SD 2.49 in the incremental HD arm. 6 months, residual renal urea clearance reduced to 2.68±SD 1.73 in the standard HD arm and 3.80±SD 1.85 in the incremental arm. In the first 6 months, 3 patients recovered to dialysis independence (standard arm=1, incremental arm=2). Slope of RRF was not significantly different between two arms (p=0.39). The proportion of patients with significant urea clearance>2ml/min/1.73m2 BSA at 6 months was significantly higher in the incremental HD arm (92%) compared to the standard HD arm (65%), p=0.032. Rate of major adverse cardiac events, fluid overload, hyperkalaemia, vascular access events, deaths and infections did not differ significantly between groups. There were 2 deaths in the standard HD arm (in 4025 patient days) versus 1 in the incremental HD arm in the first 6 months(4666 patient days).
There was no significant difference in Clinical Frailty Score, Montreal Cognitive Assessment score, depression score (PHQ-9), Quality of Life (EQ-5D-5L) and Illness Intrusiveness Rating Scale between groups at baseline and 6m time points.
Conclusion
Rate of loss of RRF (slope) was not significantly different between incremental HD and standard HD arms but incremental HD was associated with significantly higher probability of retaining urea clearance>2ml/min/1.73m2. There was no evidence of any clinical detrimental effect of incremental HD in terms of mortality, fluid overload or hyperkalaemic events. Incremental HD does not appear to be harmful and may confer a small benefit to preservation of residual renal function. A definitive study is required to define clinical benefits further.
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