Objective: To examine the variation in the risk for mortality among patients treated at renal dialysis facilities within a defined geographic area.
Setting: All free-standing and hospital-based dialysis facilities in a single southeastern state reported to the registry.
Design: Cohort of dialysis patients followed for 1 year by an end-stage renal disease registry.
Patients: Patients (n = 3612) aged 20 years and older receiving treatment at the dialysis facilities reporting to the registry during 1987.
Measurements: Demographic, comorbid, and severity of illness indicators were abstracted from patient records. Facility-specific risk estimates were derived from a Cox proportional hazards model.
Results: Facility-specific mortality rates ranged between 2.0 and 10.5 deaths per 10,000 patient days. Mortality rates were higher among older persons; whites; those with a history of diabetic nephropathy, angina, or congestive heart failure; and patients with either nutritional or functional status impairment. Facility-specific prevalence of each mortality risk factor varied widely. The unadjusted risk for death in a facility at the 75th percentile of risk was 1.3 times that of a facility at the median, whereas at the 25th percentile, it was 0.68 times as likely--a twofold range of risk. Controlling for differences in the prevalence of patient characteristics did not change the interquartile range in risks, and a facility's adjusted risk estimate showed a strong correlation with its unadjusted estimate (R2, 0.566; P less than 0.0001).
Conclusions: Patient attributes associated with increased risk for mortality vary widely among dialysis facilities. Adjustment for these differences did not, however, substantially change either the degree of variation in mortality risks or the relative ranking of a facility's mortality.