Original Investigation
Mortality risks of peritoneal dialysis and hemodialysis

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Abstract

Studies of outcomes associated with dialysis therapies have yielded conflicting results. Bloembergen et al showed that prevalent patients on continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD) had a 19% higher mortality risk than hemodialysis patients, and Fenton et al, analyzing Canadian incident patients, found a 27% lower risk. Attempting to reconcile these differences, we evaluated incident Medicare patients (99,048 on hemodialysis, 18,110 on CAPD/CCPD) from 1994 through 1996, following up to June 30, 1997. Patients were followed to transplantation, death, loss to follow-up, 60 days after modality change, or end of the study period. For each 3-month survival period, we used an interval Poisson regression to compare death rates, adjusting for age, gender, race, and primary renal diagnosis. A Cox regression was used to evaluate cause-specific mortality, and proportionality was addressed in both regressions by separating diabetic and nondiabetic patients. The Poisson regressions showed CAPD/CCPD to have outcomes comparable with or significantly better than hemodialysis, although results varied over time. The Cox regression found a lower mortality risk in nondiabetic CAPD/CCPD patients (women younger than 55 years: risk ratio [RR] = 0.61; Cl, 0.59 to 0.66; women age 55 years or older: RR = 0.87; Cl, 0.84 to 0.91; men younger than 55 years: RR = 0.72; Cl, 0.67 to 0.77; men age 55 years or older: RR = 0.87; Cl, 0.83 to 0.92) and in diabetic CAPD/CCPD patients younger than 55 (women: RR = 0.88; Cl, 0.82 to 0.94; men: RR = 0.86; Cl, 0.81 to 0.92). The risk of all-cause death for female diabetics 55 years of age and older, in contrast, was 1.21 (Cl, 1.17 to 1.24) for CAPD/CCPD, and in cause-specific analyses, these patients had a significantly higher risk of infectious death. We conclude that, overall, within the first 2 years of therapy, short-term CAPD/CCPD appears to be associated with superior outcomes compared with hemodialysis. It also appears that patients on the two therapies have different mortality patterns over time, a nonproportionality that makes survival analyses vulnerable to the length of follow-up. Further investigation is needed to evaluate both the potential explanations for these findings and the use of more advanced statistical methods in the analysis of mortality rates associated with these dialytic therapies.

Section snippets

Methods

Medicare eligibility for ESRD patients was determined through a complex set of requirements. In-center hemodialysis patients who were at least 65 years old, who were medically disabled, or who had railroad retirement insurance received Medicare entitlement from the first day of ESRD onset. In-center hemodialysis patients who did not meet any of these criteria, however, had to wait 90 days for Medicare eligibility. In addition, in-center hemodialysis patients with employer group health plans

Modality distribution

Table 1 shows the distribution of patients by modality, age, gender, and race.

. Patient Distribution by Modality, Gender, Race, and Renal Diagnosis, 1994 to 1996

Empty CellHD (n = 99,048)CAPD/CCPD (n = 18,110)P
NDM (%)DM (%)NDM (%)DM (%)
Female <55
   White66.369.633.730.40.010
   Black78.583.221.516.80.001
   Other67.174.632.925.40.003
55+
   White85.685.214.414.80.306
   Black92.992.27.17.80.084
   Other89.989.710.110.30.856
Male <55
   White71.272.128.827.90.392
   Black84.585.215.513.80.511
   Other76.784.723.315.3

Discussion

Using a Poisson regression, we found that outcomes for incident patients on CAPD/CCPD were comparable with or significantly better than those of hemodialysis patients within the first 2 years of follow-up. Our Cox regression analysis, which separated patients by diabetic status, showed that CAPD/CCPD had significantly lower risks in nondiabetic patients, comparable risks in most diabetics, and higher risks only in female diabetics 55 years of age and older.

Our analysis did not confirm the

Conclusion

Our analysis of a pure incident dialysis population indicates that, within the first 2 years of follow-up, nondiabetics have significantly better outcomes overall on CAPD/CCPD than on hemodialysis, as do younger diabetic patients. The greater mortality risk for older female diabetic patients, noted not only in our study but in that of Vonesh and Moran, suggests that these patients may be at risk for infectious complications, a finding that should be more carefully evaluated. Our results also

Acknowledgements

Acknowledgment: The authors thank Dana D. Knopic for manuscript preparation and management of the regulatory elements of the HCFA data and Shu Chen for preparing the analytical files.

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    Received April 5, 1999; accepted in revised form July 2, 1999.

    Supported in part through an unrestricted research grant from the Minneapolis Medical Research Foundation and Baxter Healthcare Corporation, McGaw Park, IL.

    Address reprint requests to Allan J. Collins, MD, Nephrology Analytical Services, 914 South 8th Street, Suite-D206, Minneapolis, MN 55404. E-mail: [email protected]

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