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Health disparities in chronic kidney disease: Are we making any progress?

April 27, 2011
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Introduction
Racial and ethnic disparities in the development of end-stage renal disease have been documented for the last quarter of a century. A landmark report from the Institute of Medicine1 documented continuing health disparities between white Americans and all other racial groups in many aspects of medicine, including ESRD and transplantation. Although access to dialysis is available, there is evidence that disparities in progression of chronic kidney disease, access to home dialysis modalities, and access to and receipt of kidney transplantation still exists. In addition, differences in kidney transplantation rates are also apparent in rural versus urban settings.

Are we making progress in the health disparities associated with CKD? Are those who need it most realizing the promise of transplantation? This article will review briefly some of the health disparities found in CKD and ESRD, which was the focus of the Health Disparities session held at the National Kidney Foundation 2009 Spring Clinical Meetings in March.

CKD
Currently 27 million people in the United States are affected by CKD.2 Racial and ethnic minorities have similar rates of early stages of CKD but may be prone to faster progression to ESRD.3 In addition, among individuals with CKD under the age of 65 years, black Americans have a higher mortality rate than whites.4 Furthermore, minorities have greater prevalence of CKD risk factors, such as micro and macroalbuminuria, hypertension, obesity, and diabetes.5 Many of these risk factors lead to increased CKD associated costs, which reached over $32 billion in 2005 and were found to be higher for black Americans compared to whites.3 Even in insured or veteran populations, diabetic black Americans, Latinos, and Asians have a higher incidence rate of ESRD.6,7 Given the high incidence rate of ESRD in insured populations, exploration of novel risk factors for CKD progression, such as health literacy, medication adherence, physician perception, interaction with the health care system, and access to preventive CKD care, may provide insight to continued health disparities in this area.

CKD in the uninsured population
More than 47 million Americans (16% of the population) have no health insurance to allow for screening and treatment of CKD risk factors such as diabetes, hypertension, and albuminuria.8 Contrary to prior assumptions about the health of the uninsured,9 a recent study estimated that 11.4 million, or nearly one-third of working-age Americans without health insurance, had at least one chronic condition, including cardiovascular disease, diabetes, and hypertension.10 In many instances, ESRD is a preventable disease. Interventions such as blood pressure lowering and use of angiotensin converting enzyme inhibitors (ACEI) or angiotensin II receptor antagonists (ARB) are effective in slowing progression of CKD if initiated at earlier stages in the disease process.11-15 However, the Medicare ESRD program only covers persons whose CKD has already advanced to the point where they require maintenance dialysis and does not cover persons with earlier stages of CKD who may benefit from such preventive interventions.

Rural health issues and CKD
Nearly 25% of the U.S. population lives in rural areas, and the health differences between rural and urban populations have been well described. Rural areas have a relative shortage of physicians, an older population, more poverty, and less insured residents.16 In November 2004 the Institute of Medicine released the "Quality through Collaboration: The Future of Rural Health" report and the recommendations called for rural health system reform demonstration projects, which included: engaging federal policymakers, developing rural care workforce, strengthening financial viability of medical facilities, and investing in information and communication technology.17 The special needs of rural patients with CKD were not specifically addressed in the report and very little has been published addressing the rural issues in these patients. However, the IOM report does provide a framework to use in assessing the needs of rural patients with CKD and to ask appropriate questions. For example, when comparing urban and rural patient with ESRD, does the quality of care differ? Are dialysis facilities located in areas most needed for rural patients? Are home therapies readily available to patients living in remote rural areas? Do racial and ethnic disparities exist in these rural areas?

Some interesting and practical approaches to providing renal replacement therapy have been developed and published in countries with large remote rural areas, such as Australia and Canada.18-20 Unfortunately, these approaches have not been extensively studied in the United States. In a study published in 2006, we hypothesized that the structure and quality of dialysis care would be substantially different and patient outcomes worse in rural compared with urban areas, and we were surprised to find the overall care was comparable between rural and urban patients.21 In comparison to urban dialysis patients, rural patients were older, more likely to be white, and had a higher percentage of comorbidities such as diabetes, cardiac disease, peripheral arterial disease, smoking, and strokes. The percentage of patients choosing home modalities after initiation of dialysis was higher in rural patients with the PD utilization of 11%, 13%, 15%, and 17% in urban, large rural, small rural, and small remote rural areas, respectively. At the time of the study, home hemodialysis utilization rates were rare in both urban and rural areas. Despite the potential advantages to home therapies in rural areas, dialysis units in rural areas were less likely to offer home therapies such as peritoneal dialysis or home hemodialysis than their urban counterparts.

More recent U.S. Renal Data System data show the growth of home hemodialysis in urban areas with a relative decrease in rural areas.24 The lower than expected utilization of home therapies in rural areas could be related to certificate of need requirements in certain states. Among the many principles used to project the need for additional dialysis stations, the goal of having a dialysis facility no farther than 30 miles from the patients'' homes likely reduces the demand for home therapies in certain states like North Carolina.22

We also explored patient survival and transplant rates in a cohort of 552,279 patients who initiated dialysis between Jan. 1, 1995 and Dec. 31, 2002.21 Most patients living in rural areas had similar if not better survival rates than their urban counterparts. Among racial subgroups including in black Americans, survival was the same or greater in rural areas. However, transplant rates were lower for black Americans living in large rural and small rural areas as compared to urban black Americans, and interestingly, whites living in rural areas had higher transplantation rates than their urban counterparts. A recent paper reported that, when compared to urban residents, rural residents had lower waiting list registration and lower relative kidney transplant rates.23 Once transplanted, both rural and urban patients enjoyed similar post transplantation outcomes.

Despite many theoretical concerns with the care delivered to rural patients with CKD, preliminary evidence provides some reassurance that a large disparity does not exist between urban and rural patients. Access to kidney transplantation in rural areas especially among racial and ethnic minorities warrants more scrutiny and more efforts to improve access to these services, which are for the most part concentrated in urban centers. Much work remains to be done in understanding rural America, which is very diverse. We need to explore the rural renal care delivered to rural black Americans in the South, American Indians in many of the rural reservations across the country, and rural Hispanics in the Southwest.

Health disparities in ESRD
The USRDS estimates that by 2010 approximately 600,000 individuals will progress to ESRD, and by the year 2030, 50% of the ESRD population will be composed of ethnic minorities.3 Notably, the likelihood of progressing to kidney failure is two to four times greater for black Americans, two to three times greater for Hispanics, and two times greater for Asian Americans compared to whites.24 While prevention programs in the Native American communities have decreased, the overall incidence rate of ESRD (which is still much greater than that of the general public),25 continues to rise for black Americans (769.6/million), who now have one of the highest rates of ESRD in the world (compared to 404.0/million in Taiwan).24 Racial and ethnic minorities are still much less likely to be listed for a kidney transplant, less likely to receive a preemptive transplant, and are two to three times less likely to be transplanted once listed than whites.26 Furthermore, pediatric and young adult patients are 1.5 to 3 times less likely to receive a kidney transplant within three years of starting dialysis compared to whites. However, once on dialysis, access to general medical care and procedures such as cardiac catheterization becomes available,27 which may lead to decreased mortality and cardiac events for minorities.28 Clearly racial disparities in the prevalence and outcomes of CKD, transplantation, and ESRD are well established; however further research into improving access to transplantation is needed.

Summary
Health disparities in CKD remain widespread and deserve continued efforts towards elimination. Future research and policy goals should be targeted towards an understanding of the contribution of health care system practices, poor health literacy, lack of access to health care, urban segregation, and on rural isolation on the perpetuation of CKD health disparities. Eliminating these disparities will require understanding the contribution of health care system practices, geography, health care policy, biology, and genetics, which can lead to the development of novel interventions, innovative health care strategies, and ground-breaking policy interventions targeted at decreasing CKD associated health disparities.

References
1. Institute of Medicine. Unequal Treatment; Confronting Racial and Ethnic Disparities in Health Care. Washington, D.C.: The National Academies Press, 2002

2. Coresh J, Selvin E, Stevens LA, et al. Prevalence of chronic kidney disease in the United States. JAMA. Nov 7 2007;298(17):2038-2047

3. U.S. Renal Data System. USRDS 2007 Annual Data Report. Bethesda, Md., National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2005: http://www.usrds.org/adr.htm

4. Mehrotra R, Kermah D, Fried L, Adler S, Norris K. Racial differences in mortality among those with CKD. J Am Soc Nephrol. Jul 2008;19(7):
1403-1410

5. Bryson CL, Ross HJ, Boyko EJ, Young BA. Racial and ethnic variations in albuminuria in the U.S. Third National Health and Nutrition Examination Survey (NHANES III) population: associations with diabetes and level of CKD. Am J Kidney Dis. Nov 2006;48(5):720-726

6. Karter AJ, Ferrara A, Liu JY, Moffet HH, Ackerson LM, Selby JV. Ethnic disparities in diabetic complications in an insured population. JAMA. May 15 2002;287(19):2519-2527

7. Young BA, Maynard C, Boyko EJ. Racial differences in diabetic nephropathy, cardiovascular disease, and mortality in a national population of veterans. Diabetes Care. Aug 2003;26(8): 2392-2399

8. Census UBot. Current Population Survey, 2000-2007 Annual Social and Economic Supplements. Historical Health Insurance Tables. 2008. http://www.census.gov/ hhes/www/hlthins/hlthins.html

9. Economic Report to the Present. Chapter 10, pages 196-198. http://www.gpoaccess.gov/usbudget/fy05/pdf/2004_erp.pdf

10. Wilper AP, Woolhandler S, Lasser KE, McCormick D, Bor DH, Himmelstein DU. A national study of chronic disease prevalence and access to care in uninsured U.S. adults. Ann Intern Med. Aug 5 2008;149(3):170-176

11. Randomized placebo-controlled trial of effect of ramipril on decline in glomerular filtration rate and risk of terminal renal failure in proteinuric, non-diabetic nephropathy. The GISEN Group (Gruppo Italiano di Studi Epidemiologici in Nefrologia). Lancet. Jun 28 1997;349(9069):1857-1863

12. Brenner BM et al. Effects of losartan on renal and cardiovascular outcomes in patients with type 2 diabetes and nephropathy. N Engl J Med. Sep 20 2001;345(12):861-869

13. Jafar TH et al. Progression of chronic kidney disease: the role of blood pressure control, proteinuria, and angiotensin-converting enzyme inhibition: a patient-level meta-analysis. Ann Intern Med. Aug 19 2003;139(4):244-252

14. Lewis EJ et al. Renoprotective effect of the angiotensin-receptor antagonist irbesartan in patients with nephropathy due to type 2 diabetes. N Engl J Med. Sep 20 2001;345(12):851-860

15. Wright JT et al. Effect of blood pressure lowering and antihypertensive drug class on progression of hypertensive kidney disease: results from the AASK trial. JAMA. Nov 20 2002;288(19):
2421-2431

16. Rosenblatt RA. A view from the periphery - health care in rural America. N Engl J Med. Sep 9 2004;351(11):1049-1051

17. Institute of Medicine. Committee on the Future of Rural Health Care. Quality through collaboration the future of rural health. Washington, D.C: National Academies Press; 2005

18. Carruthers D, Warr K. Supporting peritoneal dialysis in remote Australia. Nephrology (Carlton). Dec 2004;9 Suppl 4:S129-133

19. Tonelli M et al. Mortality of Canadians treated by peritoneal dialysis in remote locations. Kidney Int. Oct 2007;72(8):1023-1028

20. Villarba A, Warr K. Home hemodialysis in re-mote Australia. Nephrology (Carlton). Dec 2004;9 Suppl 4:S134-137

21. O''Hare AM, Johansen KL, Rodriguez RA. Dialysis and kidney transplantation among patients living in rural areas of the United States.
Kidney Int. Jan 2006;69(2):343-349

22. North Carolina Semiannual Dialysis Report July 2008. North Carolina Department of Health and Human Services. http://www.dhhs.state.nc.usdhsr/mfp/pdf/sdr2008july.pdf

23. Axelrod DA, Guidinger MK, Finlayson S, et al. Rates of solid-organ wait-listing, transplantation, and survival among residents of rural and urban areas. JAMA. Jan 9 2008;299(2):202-207

24. U.S. Renal Data System. USRDS 2007 Annual Data Report. Bethesda, Md., National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2008: http://www.usrds.org/adr.htm

25. Narva AS. Reducing the burden of chronic kidney disease among American Indians. Adv Chronic Kidney Dis. Apr 2008;15(2):168-173

26. Agency for Healthcare Research and Quality 2007 Health Disparities Report. 2007. http://www.ahrq.gov/qual/qrdr07.htm

27. Daumit GL, Hermann JA, Coresh J, Powe NR. Use of cardiovascular procedures among black persons and white persons: a 7-year nationwide study in patients with renal disease. Ann Intern Med. Feb 2 1999;130(3):173-182

28. Young BA, Rudser K, Kestenbaum B, Seliger SL, Andress D, Boyko EJ. Racial and ethnic differences in incident myocardial infarction in end-stage renal disease patients: The USRDS. Kidney Int. May 2006;69(9):1691-1698
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Dr. Young and Dr. Hall are with Veterans Affairs, Puget Sound Health Care System in Seattle, and Dr. Rodriguez is with the Division of Nephrology at University of Washington in Seattle.




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