Survival on Peritoneal Dialysis Varies by Age, Health, Timing

Survival on Peritoneal Dialysis Varies by Age, Health, Timing
By Crystal Phend, Staff Writer, MedPage Today
Published: December 17, 2008
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine.
ADELAIDE, Australia, Dec. 17 -- The choice between peritoneal dialysis and hemodialysis does not have a one-size-fits-all answer, researchers found.

Action Points

* Explain to interested patients that the study did not support peritoneal dialysis or hemodialysis as the optimal renal replacement treatment for all patients.

* Note that the potential for bias in the study may have been lower than in prior studies from countries with lower rates of peritoneal dialysis use, such as the U.S.

Which strategy gave the best chance of survival differed by age, health, and duration on therapy, Stephen P. McDonald, M.B.B.S., Ph.D., of the Queen Elizabeth Hospital and University of Adelaide, and colleagues reported online in the Journal of the American Society of Nephrology.

Their large registry study showed lower overall mortality rates with peritoneal dialysis during the first 90 days and from day 90 through one year, but higher mortality thereafter (all P0.001).

Younger patients without comorbidities had a mortality advantage with peritoneal dialysis compared with hemodialysis during the first few years.

They recommended peritoneal dialysis as reasonable short- and medium-term therapy for these younger, healthier patients.

Other groups, though, had no initial advantage and actually had a survival disadvantage after the first one to two years, suggesting caution, Dr. McDonald's group said.

"There are many reasons behind choice of dialysis modality," they wrote, "including quality of life, patient satisfaction, local practice and expertise, funding, and geography; however, mortality is a key consideration."

But mortality with the respective modalities has been widely debated with no consensus from registry or multicenter studies. (See: Peritoneal Dialysis Death Risk Higher Than Hemodialysis)

These studies were done in the United States and Europe, where peritoneal dialysis is used for a minority of patients.

So, the researchers investigated survival in Australia and New Zealand, where peritoneal dialysis is available at all major treatment centers with higher rates of use -- 20% to 40% -- than elsewhere. "Thus, selection bias toward peritoneal dialysis either at a patient or a unit level is less likely."

Their analysis of the Australia and New Zealand Dialysis and Transplant Registry included data on 27,015 patients, of whom 25,287 were still receiving dialysis 90 days after entry into the registry.

Overall, the all-cause mortality rate was 16.3 per 100 person-years.

In the univariate analysis, patients on peritoneal dialysis at 90 days were more likely to die during follow-up than those on hemodialysis (P0.0001).

But this risk varied over time such that the risk was similar between treatments overall in the first 12 months after the start of renal replacement therapy (P=0.85).

In multivariate analyses, mortality risk was actually lower during the first year for peritoneal dialysis patients compared with those on hemodialysis (hazard ratio 0.80, P=0.004) and then higher thereafter (HR 1.32, P0.001).

Although some prior studies had suggested body mass index was a factor in survival between the two dialysis modalities, Dr. McDonald's study revealed an interaction with mortality beyond one year only (P=0.0018) and without a difference between BMI groups.

The researchers noted a statistically and clinically significant association of peritoneal dialysis with a more than 50% lower mortality risk over the first 12 months for patients who were under age 60 and had no comorbidities and a trend for decreased risk among those under 60 with comorbidities.

From 90 days through one year, the lowest mortality risk was among those who stuck with peritoneal dialysis from database entry. Those who started on peritoneal dialysis and then switched to hemodialysis were at higher risk than those who started on hemodialysis regardless of whether they then switched.

Beyond one year, those who stayed on hemodialysis through 90 days had the lowest mortality whereas there was little difference between the other three peritoneal dialysis and switch groups.

Reasons for the changing risk in this and other studies may be because of better preservation of residual renal function with peritoneal dialysis, catheter use among hemodialysis patients, and other factors, the researchers said.

"Exclusion of patients who did not survive 90 days may exclude patients at risk for early mortality," they wrote. "If this group is more likely to be treated with hemodialysis, then this would tend to advantage hemodialysis."

The potential for such bias emphasizes the need for randomized trials in this area of medicine, they concluded.

The registry receives funding from the Australian Government Department of Health and Ageing, the New Zealand Ministry of Health, and Kidney Health Australia along with general support from AMGEN Australia, Novartis Pharmaceuticals Australia, Janssen-Cilag, Fresenius Medical Care Australia, Roche products, and Wyeth Australia without specific funding for this study.

Dr. McDonald reported receiving speaking honoraria from AMGEN Australia, Fresenius Australia, and Solvay Pharmaceuticals and travel grants from AMGEN Australia, Genzyme Australia, and Jansen-Cilag.

Co-authors reported conflicts of interest for Fresenius Medical Care, Baxter Healthcare, Abbott Australia, Roche Products, Novartis, and AMGEN Australia and Jansen-Cilag.

Primary source: Journal of the American Society of Nephrology
Source reference:
McDonald SP, et al "Relationship between dialysis modality and mortality" J Am Soc Nephrol 2009; DOI: 10.1681/ASN.2007111188.

Related Article(s):

* Peritoneal Dialysis Death Risk Higher Than Hemodialysis

Additional General Nephrology Coverage

Find this article at:
http://www.medpagetoday.com/Nephrology/GeneralNephrology/12209