Patient Survival Similar between Hemodialysis and Peritoneal Dialysis

The cost of caring for patients with end-stage renal disease (ESRD) is driven largely by the provision of maintenance, including costs related to dialysis. Healthcare costs for patients with ESRD in 2013 in the United States exceeded $25 million, approximately 7% of all Medicare expenditures (patients with ESRD made up <0.5% of the Medicare population in that year).

Compared with in-center hemodialysis, peritoneal dialysis is related to cost savings for the healthcare system; however, peritoneal dialysis remains underused. Some jurisdictions have introduced strategies aimed at increasing use of peritoneal dialysis, including implementation of the ESRD Prospective Payment System.

However, according to Ben Wong, MD, MSc, and colleagues in Canada, neither modality has been consistently shown to provide a clear benefit to patient survival in previous trials. According to the researchers, not restricting study participants to patients eligible for both therapies has been a key limitation to earlier studies.

Dr. Wong et al, recently conducted a retrospective cohort study designed to compare survival in incident patients with ESRD treated with either hemodialysis or peritoneal dialysis who were eligible for both therapies. A secondary objective was quantification of the impact of including ineligible patients on mortality in prior comparisons of hemodialysis and peritoneal dialysis. Results were reported in the American Journal of Kidney Diseases [2018;71(3):344-351].

The study utilized data collected from January 2004 through December 2013 from seven centers that participated in the Dialysis Measurement Analysis and Reporting (DMAR) system: Sunnybrook Health Sciences Center, Halton Healthcare, London Health Sciences Center, Grand River Hospital, Sault Area Hospital, William Osler Health Center, and the Ottawa Hospital. Eligible study participants received at least one outpatient dialysis treatment and completed a multidisciplinary modality assessment.

The researchers constructed three different patient cohorts: (1) all patients who had completed modality assessment, regardless of eligibility for peritoneal dialysis (traditional cohort); (2) patients judged eligible for both dialysis modalities (eligible cohort); and (3) patients judged eligible for both modalities who initiated dialysis therapy electively as outpatients (eligible outpatient cohort).

There were 2146 patients who had confirmed ESRD and had at least one outpatient dialysis treatment. Following application of exclusion criteria (previous transplant, <6 months of potential follow-up, gaps >1 month in follow-up, gaps of >31 days in dialysis treatment, and recovered kidney function within 6 months), the traditional cohort included 2032 patients (1569 receiving hemodialysis and 453 receiving peritoneal dialysis). Median follow up was 520 days. Overall, compared with patients on peritoneal dialysis, those receiving hemodialysis were older and had a higher frequency of diabetes, coronary artery disease, congestive heart failure, cerebrovascular disease, malignancy, and peripheral vascular disease. Hemodialysis patients also had lower hemoglobin and albumin values at dialysis initiation, had more inpatient dialysis therapy starts, and were less likely to have received a minimum of 4 months of predialysis care.

The eligible cohort included 1376 patients (926 hemodialysis recipients and 450 peritoneal dialysis recipients). The cohort represented 68% of those who completed modality assessment and were judged eligible for hemodialysis and peritoneal dialysis. Follow-up continued for a median of 547 days. In the eligible cohort, hemodialysis patients had a higher burden of comorbid conditions and were more likely to initiate dialysis therapy in an inpatient setting. Eighty-four percent of the hemodialysis patients in the eligible cohort dialyzed via a central venous catheter (CVC).

The eligible outpatient cohort included 874 patients (465 hemodialysis and 409 peritoneal dialysis) who electively initiated dialysis therapy. Those patients were followed up for a median of 564 days. Baseline characteristics of patients receiving either hemodialysis or peritoneal dialysis were more homogeneous. CVC use among those receiving hemodialysis remained high (73%).

In the traditional cohort, there were 628 deaths (31%); of those, 530 occurred in the hemodialysis group and 98 in the peritoneal dialysis group, for event rates of 0.65 and 0.42 deaths per 1000 patient-days, respectively. There was a significant interaction between age and dialysis modality (P=.02) and a time-varying association between dialysis modality and mortality (before and after year 3).

There was no statistically significant difference in all-cause mortality between hemodialysis and peritoneal dialysis in older participants (65 to 74 years of age and ≥75 years of age). In participants <65 years of age, when compared with hemodialysis in the first 3 years of dialysis therapy, there was an association between peritoneal dialysis and a significantly lower risk of death (adjusted hazard ratio for peritoneal dialysis vs hemodialysis [HRPD-HD], 0.60; 95% confidence interval [CI], 0.42-0.86).

There were 333 deaths in the eligible cohort (239 in the hemodialysis group and 94 in the peritoneal dialysis group); event rate of 0.47 and 0.38 deaths per 1000 patient-days, respectively. There was significant interaction between age and dialysis modality in this group as well. Age was again identified as an effect modifier. There was no variation over time in the effect of dialysis modality on survival, and peritoneal dialysis and hemodialysis were associated with a similar risk for death (adjusted HRPD-HD, 1.08; 95% CI, 0.82-1.42).

In the eligible outpatient cohort, there were 186 deaths (107 in the hemodialysis group and 79 in the peritoneal dialysis group); event rates were 0.41 and 0.34, respectively. None of the prespecified interaction terms were significant (age ´ modality, P=.07; sex ´ modality, P=.4; and diabetes ´ modality, P=.3). Risks for all-cause mortality were similar for those treated with peritoneal dialysis and those threated with hemodialysis (adjusted HRPD-HD, 1.19; 95% CI, 0.86-1.65), with constant estimates over time.

There were a few limitations to the study cited by the authors, including determining eligibility based on the judgment of the multidisciplinary team at each center, not performing an as-treated analysis taking into account changes in dialysis modality and/or vascular access over time for each respective incident patient, the relatively small cohort size, and not taking into account the severity of participants’ comorbid diseases.

“In conclusion, we have shown that hemodialysis and peritoneal dialysis are associated with similar mortality among incident dialysis patients who are eligible for both modalities. The effect of modality on survival does appear to change over time. Ideally, future studies should be restricted to individuals who are deemed eligible for both modalities when possible, in an attempt to reflect the outcomes of patients faced with a choice between hemodialysis and peritoneal dialysis therapy in clinical practice,” the researchers said.

Takeaway Points

  1. Canadian researchers conducted a retrospective cohort study of patients eligible for both hemodialysis and peritoneal dialysis to compare survival between the two modalities.
  2. In a cohort of patients eligible for both hemodialysis and peritoneal dialysis, both modalities were associated with similar survival regardless of age.
  3. In analyses restricted to patients initiating dialysis therapy electively as outpatients, the same finding was observed.