Switzerland

It has been a long time since the Suisse have fielded a competitive squad for global competition. The last and perhaps most illustrious international campaign was in the 1924 Olympic games - nearly a century ago. While they hold the record for the most World Cup minutes played without giving up a goal, this year's team wants far more than platitudes and cursory accomplishments. As such, it comes as no surprise that the Svizzero enter the NephroWorldCup tackling an increasingly popular modality for kidney replacement therapy: incremental hemodialysis (HD).

In a broader philosophical sense, incremental hemodialysis remains the counterbalance to the traditional dogma of thrice weekly hemodialysis. Limited/no evidence exists for the three-times-per-week hemodialysis frequency. The current one-interval-fits-all pattern ignores that which incremental hemodialysis is based: residual kidney function (RKF).

So let's level-set our understanding of incremental hemodialysis. It's often the same hemodialysis procedure (i.e., same filter, machine, prescription input categories) but offered to patients who a bare minimum of RKF that allows them to receive extracorporeal treatment 2 times per week or less ( Carousel 1).

In this era of patient-centered kidney care and personalized medicine, incremental hemodialysis offers a customized dialysis experience to each patient.

Carousel 1: A primer on incremental hemodialysis | Presented at the 2022 Delhi Society of Nephrology meeting | Courtesy of the Dr. Vijay Kher (zoom in for details)

Incremental Hemodialysis - NephroWorldCup

If incremental hemodialysis is consistent with patient-centered care, why have the Swiss decided to field a squad focused on it for this year's Tournament? In a word: outcomes.

Patient-centered options are only as good as the outcomes they result. In the (really) early years of incremental therapy, there simply was more speculation than evidence that the procedure would result in poorer outcomes than traditional thrice weekly HD. The Swiss enter this year's competition hoping to change the balance towards evidence with their retrospective analysis of incremental hemodialysis against conventional HD and....wait for it....peritoneal dialysis (PD).

In this retrospective review of 313 incident renal replacement therapy patients in the Swiss national renal registry, the type of dialysis modality chosen was analyzed for its predictive capability for one-year mortality (primary outcome) and hospitalized days (secondary outcome). The patients were divided into intermittent hemodialysis, conventional hemodialysis (3x per week), and peritoneal dialysis.

The decision of hemodialysis modality was primarily driven by the patient. In order to be considered for incremental treatment, a patient must have > 500 mL of urine per day + a urea clearance > 2 mL/minute + interdialytic weight gain < 2.5 kg. If the patient met all three criteria and selected the incremental option, s/he would begin with twice-weekly 3-hour sessions. The N for this arm was 68 patients.

If a patient qualified for and selected peritoneal dialysis, s/he would begin with the ambulatory modality of two glucose-containing daytime dwells and one icodextrin-containing nighttime dwell. The target weekly kT/V was ≥ 1.7. The N for this arm was 79 patients.

For both the primary and secondary outcomes, the main predictor variable was the initial dialysis modality selected.

Before we get to the results let's look at some of the important baseline characteristics (Figure 1). Patients in the incremental hemodialysis arm (I-HD) had a lower eGFR but far greater urine output at initiation than their conventional hemodialysis (TW-HD) counterparts.

Figure 1. Selected baseline characteristics

After a mean follow-up of 33.1 months (± 30.8 months), patients in the I-HD arm had a significantly lower all-cause mortality than their TW-HD counterparts. That finding may not surprise you, but interestingly those patients receiving I-HD also had a lower mortality than their PD counterparts (Figure 2). Unfortunately, the statistical testing performed compared I-HD to TW-HD and PD to TW-HD. The much anticipated I-HD to PD analysis was not done.

In the secondary outcome analysis, TW-HD patients had more hospitalized days and a greater drop in residual urine output than those in the I-HD and PD groups (Figure 3). Again, the latter two groups weren't directly compared to each other.

The Suisse have fielded a terrific team but it seems that they've left some of their potential back home. While the data adds more evidence to the debate between thrice weekly hemodialysis and incremental hemodialysis, it skirts and avoids any strong comparisons between incremental hemodialysis and PD. Perhaps the CVRM community is not yet ready for such an analysis and perhaps the current Suisse squad has all that it needs to be successful in this year's Tournament.