A new study confirms previous research showing an initial survival advantage with peritoneal dialysis (PD) versus hemodialysis (HD), even among patients who have received pre-dialysis care and those starting HD with an arteriovenous fistula or graft.

The study included 1,003 propensity-matched pairs of incidental PD and HD patients receiving care in the Kaiser Permanente Southern California health system. The HD cohort included only those patients who received dialysis with an arteriovenous fistula or graft during the first 90 days of the study.

The researchers excluded from final analyses HD patients who used a central venous catheter at any time during the first 90 days of dialysis. The investigators compared survival using both as-treated and intent-to-treat analyses.

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Compared with PD patients, HD patients had a 2.4 and 2.1 times greater risk of death at 1 year in as-treated and intent-to-treat analyses, respectively, the investigators, led by Victoria A. Kumar, MD, of Southern California Permanente Medical Group in Los Angeles, reported in Kidney International (2014;86:1016–1022).

PD was associated with a survival advantage for up to 3 years in the as-treated analysis, with no significant difference in adjusted survival thereafter, and up to 2 years in the intent-to-treat analysis, with no difference in adjusted survival thereafter, Dr. Kumar and her colleagues stated in their report.

Dr. Kumar’s group pointed out that other studies have demonstrated that PD patients experience a lower risk of death in the first 1–2 years after start of dialysis. Explanations include the lack of pre-dialysis care and the use of central venous catheters in HD patients. Another possibility is that PD patients have better preservation of residual renal function, according to the researchers.

“Although higher residual renal function during the first few years on PD could explain our results,” they wrote, “changes in peritoneal membrane structure over time along with reduced ultrafiltration capacity could explain why PD patients lose their survival advantage after the first few years on dialysis.”

Dr. Kumar and her colleagues noted that the strengths of their study include a large and diverse PD cohort and a relatively long follow-up time. In addition, patients appeared to be well matched in terms of baseline disease burden and demographics.

A major limitation to their study was the absence of data regarding residual renal function at the time of dialysis initiation. “The authors cannot exclude that baseline residual renal function was higher in PD patients than in matched HD patients, potentially conferring a survival benefit to the PD cohort,” they wrote.

In an accompanying editorial, Christos P. Argyropoulos, MD, and Mark L. Unruh, MD, of the Division of Nephrology in the Department of Internal Medicine at the University of New Mexico in Albuquerque, commented that the study by Dr. Kumar’s group “is an important addition to the evolving literature concerning the relative outcomes of dialysis modalities and establishes a methodological benchmark against which future studies on the same topic should be measured.”