Prior observational studies have shown multiple benefits of both frequent hemodialysis (HD) and frequent nocturnal HD compared to conventional three times per week treatments for patients with end-stage renal disease (ESRD). To test these hypotheses, the Frequent Hemodialysis Network (FHN) Trials Group conducted two multicenter randomized trials to compare conventional tree times weekly HD with (1) in-center daily and (2) home nocturnal HD. Specifically, the FHN Nocturnal trial was designed to assess the effects of frequent nocturnal home HD six times per week compared with conventional three times per week HD.

Participants with ESRD requiring maintenance dialysis were recruited from 19 clinical centers. A total of 87 subjects were enrolled, underwent baseline assessment, and were randomized to treatment, either to three times per week conventional HD or to nocturnal HD six times per week, all with single-use high-flux dialyzers. Participants were followed for 14 months. The composite of mortality with change in (1) left ventricular mass index (LVMI) by magnetic resonance imaging (MRI), and (2) SF-36 RAND Physical Health Composite (PHC) were used as co-primary outcomes to assess the efficacy of treatment. Secondary outcomes included cognitive performance, self-reported depression, laboratory markers of nutrition, mineral metabolism and anemia, blood pressure and rates of hospitalization, and vascular access interventions.

The FHN Nocturnal trial found no significant effect of nocturnal hemodialysis for either of the two co-primary outcomes. Results showed that patients in the nocturnal arm had improved control of hyperphosphatemia and hypertension, but there was no significant benefit to frequent nocturnal hemodialysis among the other main secondary outcomes. While the nocturnal study was unable to demonstrate a definitive benefit of more frequent nocturnal hemodialysis for either co-primary outcome, these results differ from the FHN Daily Trial, which showed a statistically significant benefit of more frequent hemodialysis for both co-primary outcomes. The primary objective of the FHN Nocturnal trial was to compare the effects of conventional (three times per week) and frequent (six times per week) hemodialysis treatment for patients with ESRD, specifically to assess the safety, efficacy, and cost-effectiveness of the two treatments.

The two co-primary outcome measures were: (1) death or 12-month change in LVMI (death/LVMI) as measured by MRI, and (2) death or 12-month change in the SF-36 RAND PHC (death/PHC).

The seven main secondary outcome measures consisted of group comparisons of: change in LVMI, change in PHC, change in Beck Depression Inventory score, change in Trail Making Test B score, change in pre-HD serum albumin, change in pre-HD serum phosphorus, and rates of non-access hospitalization or death.

Patients who met the following criteria were eligible for enrollment in the study:

• Diagnosis of end stage renal disease requiring chronic renal replacement therapy
• Age ≥ 18 years
• Achievement of mean eKt/V of ≥ 1.1 during baseline assessment

Exclusion criteria are documented in the study protocol.

The FHN Nocturnal trial found no significant effect of nocturnal hemodialysis for either of the two co-primary outcomes (death or left ventricular mass (measured by MRI) with a hazard ratio of 0.68, or of death or RAND Physical Health Composite with a hazard ratio of 0.91). Possible explanations for the left ventricular mass result include limited sample size and patient characteristics. In analysis of secondary outcomes, patients in the nocturnal arm were shown to have improved control of hyperphosphatemia and hypertension, but there was a trend for increased vascular access events in the nocturnal arm. There was no significant benefit to frequent nocturnal hemodialysis among the other main secondary outcomes. These results differ from the FHN Daily Trial, as in that study there was a statistically significant benefit of more frequent hemodialysis for both co-primary outcomes.