Predicting coronary heart disease after kidney transplantation: Patient Outcomes in Renal Transplantation (PORT) Study.

Traditional risk factors do not adequately explain coronary heart disease (CHD) risk after kidney transplantation. We used a large, multicenter database to compare traditional and nontraditional CHD risk factors, and to develop risk-prediction equations for kidney transplant patients in standard clinical practice. We retrospectively assessed risk factors for CHD (acute myocardial infarction, coronary artery revascularization or sudden death) in 23,575 adult kidney transplant patients from 14 transplant centers worldwide. The CHD cumulative incidence was 3.1%, 5.2% and 7.6%, at 1, 3 and 5 years posttransplant, respectively. In separate Cox proportional hazards analyses of CHD in the first posttransplant year (predicted at time of transplant), and predicted within 3 years after a clinic visit occurring in posttransplant years 1-5, important risk factors included pretransplant diabetes, new onset posttransplant diabetes, prior pre- and posttransplant cardiovascular disease events, estimated glomerular filtration rate, delayed graft function, acute rejection, age, sex, race and duration of pretransplant end-stage kidney disease. The risk-prediction equations performed well, with the time-dependent c-statistic greater than 0.75. Traditional risk factors (e.g. hypertension, dyslipidemia and cigarette smoking) added little additional predictive value. Thus, transplant-related risk factors, particularly those linked to graft function, explain much of the variation in CHD after kidney transplantation.

Racial disparity trends for graft failure in the US pediatric kidney transplant population, 1980-2004.

Graft survival among adult African American kidney transplant patients remains low compared to whites, but little information is available for children and adolescents. We examined trends in graft failure among US incident primary kidney transplant patients aged <19 years (n = 13 692), 1980-2004. Trends in 1-year and 2- to 5-year graft failure (for patients whose grafts survived the first year) were analyzed in 5-year intervals. One-year graft failure declined 70% for white and 77% for African American patients over the 25-year period, and 1-year graft failure rates improved at a slightly higher rate for African American compared to white patients (p = 0.02). In contrast, the graft failure rates for years 2-5 declined 53% for white and only 41% for African American patients over the 25 years (p = 0.29). In fully adjusted Cox proportional hazards analysis, the rate of graft failure among African Americans was approximately 2-fold higher than for white patients over the entire study period. Graft survival has improved slightly more for African American than white pediatric patients over the past 25 years. However, graft survival for African American pediatric patients remains poor compared with white patients.

Effect of comorbidity adjustment on CMS criteria for kidney transplant center performance.

The Centers for Medicare & Medicaid Services (CMS) uses kidney transplant outcomes, unadjusted for standard comorbidity, to identify centers with sufficiently higher than expected rates of graft failure or patient death (underperforming centers) that they may be denied Medicare participation. To examine whether comorbidity adjustment would affect this determination, we identified centers that would have failed to meet 1-year graft survival criteria, 1992-2005, with and without adjustment using the Elixhauser Comorbidity Index. Adjustment was performed for each U.S. center for 24 consecutive (overlapping) 30-month intervals, including 102 176 adult deceased-donor and living-donor kidney transplant patients with Medicare as primary payer 6 months pretransplant. For each interval, we determined percent positive agreement (PPA) (number of centers underperforming both before and after adjustment, divided by number underperforming either before or after adjustment). Overall PPA was 80.8%, with no evidence of a trend over time. Among deceased-donor recipients, 10 of 31 comorbid conditions were predictors of graft failure in at least half of the intervals, as were six conditions among living-donor recipients. Lack of comorbidity adjustment may disadvantage centers willing to accept higher risk patients. Risk of jeopardizing Medicare funding may give centers incentive to deny transplantation to higher risk patients.