Twice-Weekly Dialysis May Preserve Residual Kidney Function

Patients with preserved residual kidney function experience a survival benefit.
Patients with preserved residual kidney function experience a survival benefit.

Incremental hemodialysis (HD)—the initiation of HD at lower frequency—may be a safe treatment regimen for incident HD patients with substantial residual kidney function (RKF), according to a new study. In these patients, incremental HD is associated with greater preservation of RKF, investigators reported.

In a study of 23,645 HD patients, a research team led by Kamyar Kalantar-Zadeh, MD, MPH, PhD, of the University of California Irvine, compared incremental HD—whereby patients were placed on routine twice-weekly HD for more than 6 continuous weeks during the first 91 days upon transition to dialysis—with conventional thrice-weekly HD. The incremental HD group included 351 patients. Baseline renal urea clearance and urine volume were higher in these patients in the first patient-quarter compared with the 23,294 patients in the conventional group. The incremental regimen was associated with an average 17-minute shorter dialysis treatment time, less weekly cumulative percentage interdialytic weight gain (IDWG), and lower standard Kt/V. The prevalence of patients with 2.1 or higher total standard Kt/V—the recommended minimum level of urea removed according to National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) guidelines—was greater than 95% in patients with a renal urea clearance greater than 3.0 mL/min/1.73 m2 regardless of HD schedule, but differed greatly between schedules among patients with renal urea clearance of 3.0 mL/min/1.73 m2 or less (30% in the incremental group vs. 90% in the conventional group).

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Investigators matched the 351 incremental patients with 8,068 conventional HD patients according to baseline renal urea clearance, urine volume, age, sex, diabetes status, and central venous catheter use. Both renal urea clearance and urine volume showed significantly slower declines over time in the incremental versus conventional HD regimens, Dr. Kalantar-Zadeh and colleagues reported online ahead of print in the American Journal of Kidney Diseases.

In survival analyses after year 1, the investigators found no significant difference in all-cause mortality between the incremental and conventional HD groups. Among the incremental HD patients, however, subgroup analyses revealed that the incremental approach was associated with greater mortality risk among patients with inadequate RKF, renal urea clearance of 3.0 mL/min/1.73 m2 or less, and urine volume of 600 mL/day or less, but not among patients with higher baseline RKF.

In addition, results showed a significant trend toward better survival among patients in the incremental group across higher increments of renal urea clearance and lower increments of weekly IDWG, but not in urine volume categories.

“Our results suggest that twice-weekly hemodialysis may be a safe and even preferred regimen to preserve RKF over time following the initiation of maintenance dialysis therapy, especially in patients with substantial RKF,” the authors wrote. “However, caution against twice-weekly hemodialysis may be needed for patients with little or no RKF.”

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Dr. Kalantar-Zadeh's group noted that less frequent HD has been commonly prescribed in some other countries, such as China and India. NKF-KDOQI guidelines suggest a twice-weekly schedule for patients with substantial residual renal urea clearance (at least 3.0 mL/min/1.73 m2). In the United States, though, most patients initiating maintenance HD are prescribed thrice-weekly dialysis regardless of RKF.

The researchers pointed out that the estimated glomerular filtration rate is greater than 10 mL/min/1.73 m2 upon initiation of maintenance dialysis in up to 45% of patients in the United States, so the incremental HD regimen may preserve RKF and offer both clinical and economic benefits.

The authors explained that more frequent HD may lead to more rapid loss of RKF through several mechanisms, include the release of nephrotoxic inflammatory mediators during HD and ischemic kidney damage caused by intradialytic hypotension and post-dialytic hypovolemia.

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