Re-evaluating the volume-outcome relationship in hemodialysis patients

We sought to determine whether dialysis patient mortality rates are associated with differences in dialysis facility size, and whether this relationship differs among higher risk diabetic and lower-risk non-diabetic patients.

Using 186,554 adult end-stage renal disease patients initiating hemodialysis at standalone facilities in the United States between 1996 and 1999, we evaluated relationships between dialysis facility size and survival to 5 years. We performed separate analyses for patients with and without diabetes as their primary cause of end-stage renal disease. Facility size was defined according to the number of hemodialysis patients at year's end (smallor=120).

Increasing facility size was associated with a reduced risk of mortality at 4 years for both diabetic (HR=0.983 per 10 unit increase, 95% CI=0.967, 0.999) and non-diabetic patients (HR 0.977 per 10 unit increase, 95% CI=0.963, 0.992) dialyzing in small facilities, and for diabetic patients (HR 0.989 per 10 unit increase, 95% CI=0.980, 0.998) dialyzing in medium size facilities.

Smaller facility size is associated with increasing long-term mortality for in-center hemodialysis patients. This relationship appears to be more pronounced among higher-risk diabetic vs. lower-risk non-diabetic patients.