Traditional nephrology training makes us believe that it is good practice to start maintenance dialysis therapy sooner rather than later. Nevertheless, recent data indicate that we may encounter yet another “old-practice-was-wrong” paradigm shift.
Indeed for decades, there have been minority camps within the nephrology community advocating late start. Non-randomized studies by late MacKenzie Walser, MD, suggested greater survival if dialysis therapy can be deferred by months to years. Recently, studies have revived the old discussions on late versus early dialysis therapy initiation.
Observational studies show an association between higher creatinine clearance at dialysis initiation and worse outcomes, but this may be due to an association of higher serum creatinine level with larger muscle mass and greater survival. However, a recent randomized, controlled trial confirmed trends towards better outcome in the group that started dialysis therapy with lower residual renal function. It is not clear whether the dialysis therapy is inherently harmful or whether the contemporary practice of treatment causes or aggravates harm.
Thrice-weekly hemodialysis (HD) treatment may lead to subtle but cumulative mechanical and oxidative stress upon the cardiovascular system and engender hemodynamic instability. There may be repeated bouts of acute tubular necrosis by lowering blood pressure during each HD session, resulting in faster loss of residual kidney function and frequent ischemic events upon hypotensive episodes.
Exposure to foreign tubing and toxic medications may play a role. Patient anxiety that accompanies each HD treatments, along with post-HD fatigue and lightheadedness, may aggravate harm. And then there is the stress of vascular access surgery and frequent infections. Peritoneal dialysis may cause different types of harms including substantial protein loss and frequent peritonitis.
As to how to delay the start of dialysis, the old school of maintaining a low protein diet (0.6-0.7 g/kg/day) while providing amino acids and proteins of high biologically value can be attempted. In many countries outside of the United States, keto-analogues are used routinely, as are indoxyl sulfate modulators. Recent discussion about vegetarian diet that is also linked with lower phosphorus burden deserves investigation.
Fluid and salt control with or without diuretics may be used more diligently. As to the concerns of the dialysis industry that such calls to late start may interfere with the business, I have one final message. In Taiwan, where the median estimated glomerular filtration rate at dialysis initiation is less than 5 mL/min/1.73 m2, there are even more dialysis patients per general population than the United States.
Kamyar Kalantar-Zadeh, MD, MPH, PhD, is Associate Professor of Medicine and Pediatrics, and Director, Dialysis Expansin & Epidemiology, Harbor-UCLA Division of Nephrology & Hypertension Dr. Kalantar-Zadeh is Medical Director, Nephrology, for Renal & Urology News.