Cardiovascular Risk Factors, Comorbidity, and Survival Outcomes in Black and White Dialysis Patients

Early, intermediate, and long-term risk factors for mortality in incident dialysis patients: the Choices for Healthy Outcomes in Caring for ESRD (CHOICE) Study

BACKGROUND

Knowing whether risk factors for mortality differ in dialysis patients who survive longer and the strengths of these risk factors for mortality change over time would assist physicians in making better prognostic judgments.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

1,041 incident dialysis patients treated in 81 clinics (mean follow-up, 3.1 years).

PREDICTOR

A parsimonious set of risk factors (older age, white race, unemployed status, comorbidity, ever smoking, decreased systolic blood pressure, and decreased serum albumin level) chosen from several available demographic, clinical, and laboratory variables.

OUTCOMES & MEASUREMENTS

Long-term (4+ years) survival and mortality over yearly intervals of follow-up, examined in logistic regression and Cox proportional hazards analyses.

RESULTS

All baseline risk factors were associated with a decreased chance of surviving 4+ years, even after adjustment for confounders. Increased age was a strong and independent risk factor for mortality over all yearly intervals; comorbidity, smoking, and decreased blood pressure were early risk factors; low albumin level and unemployed status were intermediate risk factors; and white race was a late risk factor. When risk factors were updated with time, low albumin level and severe comorbidity became significant risk factors over most intervals.

LIMITATIONS

Lack of some follow-up data and inability to rule out residual confounding or make causal inference based on results.

CONCLUSION

Long-term survivors on dialysis therapy may have different risk factors for mortality than patients in earlier phases of end-stage renal disease (eg, race versus blood pressure); other risk factors may be constant over time (eg, age, comorbidity, and albumin level). Such information may help guide physicians in making prognostic judgments for individual patients with particular dialysis vintages.

History of myocardial infarction and stroke among incident end-stage renal disease cases and population-based controls: an analysis of shared risk factors

BACKGROUND

A history of myocardial infarction (MI) and stroke is more common among incident cases of treated end-stage renal disease (ESRD) than in the general US population.

METHODS

Whether this association is the result of shared risk factors or renal dysfunction before ESRD was examined using data from a population-based case-control study of 716 incident patients with ESRD and 361 control subjects of similar age from Maryland, Virginia, West Virginia, and Washington, DC. Medical history including a previous MI and stroke, and dates of these events were obtained by means of a structured telephone interview.

RESULTS

After adjustment for age, race, and sex, odds of ESRD were 3.6 (95% confidence interval [CI], 2.0 to 6.5) and 11.1 (95% CI, 4.3 to 28.6) times greater for those with versus without a history of MI and stroke, respectively. Adjustment for long-standing hypertension, diabetes mellitus, and several other potential confounders reduced the odds ratio (OR) of ESRD for those with a history of MI by 77% (OR, 1.6; 95% CI, 0.7 to 3.3) and 39% (OR, 7.2; 95% CI, 2.2 to 23.2) for those with a history of stroke. The OR for ESRD was higher within 5 years of an MI (OR, 2.2; 95% CI, 0.8 to 6.1) or stroke (OR, 14.9; 95% CI, 1.8 to 125) than for more distant MI (OR, 0.8; 95% CI, 0.2 to 2.5) and stroke (OR, 4.5; 95% CI, 1.0 to 19.0) events.

CONCLUSION

The high prevalence of a history of MI at ESRD incidence is explained primarily by shared risk factors, but the high prevalence of stroke is not.

Cardiovascular mortality in children and young adults with end-stage kidney disease

OBJECTIVE

To analyze cardiovascular death in a national end-stage renal disease (ESRD) population.

STUDY DESIGN

This retrospective, observational study with data from the US Renal Data Systems analyzed 1380 deaths from 1990 to 1996 among patients who started ESRD therapy as children and died before 30 years of age.

RESULTS

Percentage of cardiac deaths (n = 311) varied by age and was higher among black patients (0-4 years, 36%; 5-9 years, 18%; 10-14 years, 35%; 15-19 years, 22%; 20-30 years, 32%) than white patients (18%, 12%, 17%, 14%, and 23%, respectively). Among black patients, cardiac deaths occurred in 11% of transplant recipients, 34% of dialysis patients, and among white patients 9% and 25%, respectively. Black patients were 1.6 times more likely to die of a cardiac death (P <.001) than white patients. Transplant recipients had 78% lower risk of cardiac death than dialysis patients (odds ratio = 0.22; P =.0001). The cardiac death rate among dialysis patients was 21.4 per 1000 patient-years in black patients compared with 20.5 in white patients. Transplantation cardiac death rates were lower in black patients, 2.1 per 1000 patient-years, and 1.3 in white patients.

CONCLUSIONS

Cardiovascular death accounts for 23% of pediatric and young adult ESRD deaths. Black patients and dialysis patients are at higher risk of a cardiac death compared with white patients and transplant recipients. Further studies are needed to identify risk factors associated with cardiovascular death in patients with ESRD.

Does the survival advantage of nonwhite dialysis patients persist after case mix adjustment?

PURPOSE

Nonwhite dialysis patients survive longer than white patients; however, their clinical characteristics differ. We examined whether case mix differences explain the apparent survival advantage of nonwhite dialysis patients.

SUBJECTS AND METHODS

We performed a prospective cohort study using data from the US Renal Data System Case Mix Severity Study that included 4,797 randomly selected dialysis patients 20 years of age and older who were followed up for up to 6 years. Demographic, comorbidity, laboratory, nutritional, and functional status data were obtained. Multivariable proportional hazards models adjusted for case mix differences between nonwhite and white dialysis patients. Additional analyses examined the effects of differences in transplantation rates, withdrawal from dialysis rates, and treatment modality selection.

RESULTS

Unadjusted survival rates of black, Native American, and Asian or Pacific Islander dialysis patients were similar, and better than that for white dialysis patients. Relative to whites, the unadjusted relative risk (RR) for mortality among nonwhite patients was 0.64 (95% confidence interval [CI]: 0.58 to 0.70). Adjustment for case mix reduced, but did not eliminate, the survival advantage associated with nonwhite race (RR = 0.78, CI: 0.71 to 0.86). Adjustment for differences in transplantation rates (RR = 0.83, CI: 0.75 to 0.91), withdrawal from dialysis rates (RR = 0.81, CI: 0.73 to 0.90), and initial treatment modality (RR = 0.79, CI: 0.71 to 0.87) did not explain the lower mortality among nonwhites.

CONCLUSIONS

A survival advantage for nonwhite dialysis patients persists after case mix adjustment. Future studies should explore additional physiologic and socioeconomic factors that might explain this difference.