The impact of comorbid and sociodemographic factors on access to renal transplantation.

OBJECTIVE: To assess the impact of sociodemographic factors and comorbid conditions on access to renal transplantation for adult US dialysis patients with end-stage renal disease (ESRD).
DESIGN: Cohort analytic study. Data on comorbid conditions at onset of ESRD were abstracted from patients' medical records and matched to sociodemographic and ESRD data from the United States Renal Data System database.
SETTING: United States Medicare dialysis population. PATIENTS: Random, national sample of ESRD patients starting dialysis in 1986 and 1987 (n = 4118). MAIN OUTCOME MEASURE: Time to first renal transplant (living or cadaver donor) since onset of ESRD regressed with two nested Cox proportional hazards models, first against sociodemographic factors alone, and then against sociodemographic factors and comorbid conditions.
RESULTS: Cardiovascular diseases are most predictive of who received a transplant; patients with coronary heart disease, congestive heart failure, or left ventricular hypertrophy showed lower transplantation rates relative to patients without the disease (relative rate [RR] = 0.65 to 0.80, P < .05 each). Obese patients and patients with peripheral vascular disease also showed lower transplantation rates (RR = 0.65 to 0.75, P < .05 each). Previously reported sociodemographic effects of lower transplantation rates for older patients, women, nonwhite patients, and lower income patients were confirmed (P < .01). Sociodemographic effects remained essentially unchanged when adjusted for comorbid conditions.
CONCLUSIONS: These findings indicate that sociodemographics have strong independent effects on access to transplantation that cannot be explained away as "surrogate" effects related to comorbid factors. Furthermore, the results suggest that lower mortality rates for transplant recipients relative to dialysis patients are due, in part, to a healthier case mix among patients receiving transplants.