Geography Matters: Relationships among Urban Residential Segregation, Dialysis Facilities, and Patient Outcomes

Geography Matters: Relationships among Urban Residential Segregation, Dialysis Facilities, and Patient Outcomes

From San Francisco General Hospital, University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, and Veterans Affairs San Francisco Research Enhancement Award Program, San Francisco, California.

Abstract

Background: End-stage renal disease disproportionately affects black Americans. However, the impact of residential segregation by race—a prominent feature of many U.S. cities—on outcomes of patients receiving dialysis and on facility performance has not been evaluated.

Objective: To examine the relationship among racial composition of ZIP codes in metropolitan areas, outcomes of patients receiving dialysis, and characteristics of dialysis facilities.

Design: Retrospective cohort study of patients receiving dialysis and cross-sectional study of dialysis facilities.

Setting: U.S. metropolitan ZIP codes with differing percentages of black residents.

Patients: Black and non-Hispanic white patients who initiated long-term dialysis between 1 January 1995 and 31 December 2002 (n = 399 424) and dialysis facilities in operation in December 2004 (n = 3244).

Measurements: Mortality and time to transplantation among patients receiving dialysis, and performance of dialysis facilities on the basis of quality indicators (anemia management, dialysis adequacy, and facility-level mortality rates).

Results: Most black patients (50.3%) but few white patients (5%) lived in the 3% (n = 769) of ZIP codes in which most residents were black. In analyses adjusted for patient and ZIP code characteristics, mortality rates were higher among white patients but not among black patients living in areas with a higher percentage of black residents (adjusted hazard ratio for ZIP codes with ≥75% black residents vs. <10% black residents, 1.14 [95% CI, 1.07 to 1.21] for white patients and 1.02 [CI, 0.99 to 1.06] for black patients). Time to transplantation was longer among both black and white patients (adjusted hazard ratio for ZIP codes with ≥75% black residents vs. <10% black residents, 0.84 [CI, 0.78 to 0.92] and 0.63 [CI, 0.57 to 0.71] for black patients and white patients, respectively). Dialysis facilities located in areas with a higher percentage of black residents were more likely to have higher-than-expected mortality rates and were less likely to meet performance targets.

Limitations: Patient-level analyses were restricted to black and non-Hispanic white patients. Patient-level and facility-level analyses focused only on the percentage of black residents in each ZIP code.

Conclusions: The racial composition of urban residential areas is associated with time to transplantation and dialysis facility performance on standard quality measures. Closer scrutiny of care provided to patients receiving dialysis who live in predominantly black residential areas and to dialysis facilities operating in these areas may be warranted.

Article and Author Information

Note: This manuscript was presented in abstract form at the Renal Disease in Minority Populations and Developing Nations satellite meeting of the International Society of Nephrology, Singapore, 30 June–2 July 2005, and at the Veterans Affairs Health Services Research and Development meeting, Arlington, Virginia, 16–17 February 2006.
Acknowledgments: The authors thank the patients and staff of the dialysis unit at the San Francisco General Hospital for inspiring this study. They also thank Dr. Barbara Grimes for technical assistance in implementing the multiple imputation procedure.
Grant Support: Dr. O'Hare is supported by a Paul Beeson Career Development Award in Aging from the National Institute of Aging (K23 AG 028980-01). This research was also supported by Veterans Affairs Health Services Research and Development Career Development Awards to Drs. O'Hare and Moody-Ayers. Dr. Sen is supported in part by the Veterans Affairs San Francisco Health Services Research and Development Research Enhancement Award Program to Improve Care for Older Veterans.
Potential Financial Conflicts of Interest: None disclosed.
Requests for Single Reprints: Rudolph A. Rodriguez, MD, University of California, San Francisco, San Francisco General Hospital, Renal Center Building 100, Room 350, Box 1341, San Francisco, CA 94110; e-mail, rrodriguez{at}medsfgh.ucsf.edu.
Current Author Addresses: Dr. Rodriguez: University of California, San Francisco, San Francisco General Hospital, Renal Center Building 100, Room 350, Box 1341, San Francisco, CA 94110.
Drs. Sen and Bacchetti: University of California, 185 Berry Street, Suite 5700, San Francisco, San Francisco, CA 94107.
Dr. Mehta, MS. Moody-Ayers, and Dr. O'Hare: San Francisco Veterans Affairs Medical Center, 4150 Clement Street, Box 151G, San Francisco, CA 94121.
Author Contributions: Conception and design: R.A. Rodriguez, A.M. O'Hare.
Analysis and interpretation of the data: R.A. Rodriguez, S. Sen, P. Bacchetti, A.M. O'Hare.
Drafting of the article: R.A. Rodriguez, P. Bacchetti, A.M. O'Hare.
Critical revision of the article for important intellectual content: R.A. Rodriguez, S. Sen, K. Mehta, S. Moody-Ayers, P. Bacchetti, A.M. O'Hare.
Final approval of the article: R.A. Rodriguez, S. Sen, K. Mehta, S. Moody-Ayers, P. Bacchetti, A.M. O'Hare.
Provision of study materials or patients: R.A. Rodriguez, A.M. O'Hare.
Statistical expertise: S. Sen, P. Bacchetti, A.M. O'Hare.
Administrative, technical, or logistic support: R.A. Rodriguez, A.M. O'Hare.
Collection and assembly of data: R.A. Rodriguez, A.M. O'Hare.