The relationship between the delivered dose of hemodialysis and patient mortality remains somewhat controversial. Several observational studies have shown improved patient survival with higher levels of delivered dialysis dose. However, several other unmeasured variables, changes in patient mix or medical management may have impacted on this reported difference in mortality. The current study of a U.S. national sample of 2,311 patients from 347 dialysis units estimates the relationship of delivered hemodialysis dose to mortality, with a statistical adjustment for an extensive list of comorbidity/risk factors. Additionally this study investigated the existence of a dose beyond which more dialysis does not appear to lower mortality. We estimated patient survival using proportional hazards regression techniques, adjusting for 21 patient comorbidity/risk factors with stratification for nine Census regions. The patient sample was 2,311 Medicare hemodialysis patients treated with bicarbonate dialysate as of 12/31/90 who had end-stage renal disease for at least one year. Patient follow-up ranged between 1.5 and 2.4 years. The measurement of delivered therapy was based on two alternative measures of intradialytic urea reduction, the urea reduction ratio (URR) and Kt/V (with adjustment for urea generation and ultrafiltration). Hemodialysis patient mortality showed a strong and robust inverse correlation with delivered hemodialysis dose whether measured by Kt/V or by URR. Mortality risk was lower by 7% (P = 0.001) with each 0.1 higher level of delivered Kt/V. (Expressed in terms of URR, mortality was lower by 11% with each 5 percentage point higher URR; P = 0.001). Above a URR of 70% or a Kt/V of 1.3 these data did not provide statistical evidence of further reductions in mortality. In conclusion, the delivered dose of hemodialysis therapy is an important predictor of patient mortality. In a population of dialysis patients with a very high mortality rate, it appears that increasing the level of delivered therapy offers a practical and efficient means of lowering the mortality rate. The level of hemodialysis dose measured by URR or Kt/V beyond which the mortality rate does not continue to decrease, though not well defined with this study, appears to be above current levels of typical treatment of hemodialysis patients in the U.S.

We sought to determine whether lower mortality rates reported with hemodialysis (HD) at home compared to hemodialysis in dialysis centers (center HD) could be explained by patient selection. Data are from the United States Renal Data System (USRDS) Special Study Of Case Mix Severity, a random national sample of 4,892 patients who started renal replacement therapy in 1986 to 1987. Intent-to-treat analyses compared mortality between home HD (N = 70) and center HD patients (N = 3,102) using the Cox proportional hazards model. Home HD patients were younger and had a lower frequency of comorbid conditions. The unadjusted relative risk (RR) of death for home HD patients compared to center HD was 0.37 (P < 0.001). The RR adjusted for age, sex, race and diabetes, was 44% lower in home HD patients (RR = 0.56, P = 0.02). When additionally adjusted for comorbid conditions, this RR increased marginally (RR = 0.58, P = 0.03). A different analysis using national USRDS data from 1986/7 and without comorbid adjustment showed patients with training for self care hemodialysis at home or in a center (N = 418) had a lower mortality risk (RR = 0.78, P = 0.001) than center HD patients (N = 43,122). Statistical adjustment for comorbid conditions in addition to age, sex, race, and diabetes explains only a small amount of the lower mortality with home HD.

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The present study evaluated end-stage renal disease (ESRD) patient survival in Lombardy, Italy, and the United States (U.S.) using data from two registries, the Lombardy Dialysis and Transplant Registry (RLDT) and the U.S. Renal Data System (USRDS), respectively. For this purpose, 4,196 white patients (2,900 from the USRDS Case Mix Severity Study and all 1296 from RLDT) who started renal replacement therapy in 1986 and 1987 were studied. Compared to Lombardy patients, those in the USA were significantly older (mean age 59.9 +/- 16.4 vs. 55.9 +/- 14.7 years), had a lower proportion of males (53.7 vs. 62.1%), a greater proportion with diabetic nephropathy (29.9 vs. 9.7%) and a significantly greater proportion of patients with the recorded comorbid conditions (heart disease, peripheral vascular disease, cirrhosis, cachexia, malignancy). U.S. patients were less frequently treated with peritoneal dialysis (PD) by day 30 of ESRD (21.2 vs. 30.7). Survival was compared in the Cox proportional hazard regression model, using age, sex, comorbid conditions and early modality of treatment as explanatory covariates. Overall, 48% of the 4196 patients died during the 48 to 72 months follow-up to 12/31/91. Per 100 patient-years the gross death rate for USRDS patients was 28.7 compared to 13.0 of RLDT patients. The unadjusted death relative risk for RLDT was 0.439, that is, 56% lower death rate compared to USRDS patients. Age, sex, diabetic status, each of the recorded comorbid conditions and treatment modality were significantly related to survival and included in the model. The Cox cumulative survival adjusted for all these explanatory covariates survival was for U.S. patients 84.4% at one year, 67.0% at two years and 33.4% at five years, and for RLDT patients 88.3% at one year, 75.9% at two years and 45.9% at five years. The relative mortality risk (RR) for the patients treated in Lombardy adjusted for all the reported covariates was 29% lower than for US patients (RR = 0.71; P < 0.0001). This comparative risk varied significantly by age (P < 0.0001) and was 65 percent lower for Lombardy compared to U.S. patients in the age range 25 to 44 years (RR = 0.35) and about 20% lower for patients over age 65 years (RR = 0.80). This relative risk was mainly related to hemodialysis and was not statistically significant for PD patients. The observed lower mortality risk in Lombardy was less pronounced when adjusted for demographic and comorbid covariates, but was still large and therefore suggests the need for further studies regarding treatment related factors and unmeasured patient factors, particularly in hemodialysis patients.