- Email: [email protected]
The Aging Pandemic: Demographic Changes in the General and End-Stage Renal Disease Populations
The Aging Pandemic: Demographic Changes in the General and End-Stage Renal Disease Populations Paul W. Eggers, PhD Summary: The aging of the US population, and Western society populations in general, has been of concern to demographers and health planners for a number of years. The implications of this demographic shift include both increased economic and health care burdens for the United States. The growth of the end-stage renal disease population in the 1980s and 1990s suggested massive increases in this very expensive and frail population. However, recent incidence rates suggest that future growth may not be as great as thought just a few years ago. Semin Nephrol 29:551-554 Published by Elsevier Inc. Keywords: ESRD, epidemiology, aging, renal disease, populations
he presence of the baby boomer bulge in the US population caused by the post– World War II spike in fertility has been the subject of demographic study for decades as the baby boomers moved through childhood, college years, and early adulthood (producing a smaller baby boomer echo of children). Beginning in the 1970s there has been a decline in the overall fertility rate. This, combined with the impending retirement of the baby boomer population has led to continual debates in Congress about the implications for the solvency of the Social Security and Medicare trust funds. This debate has become even more urgent as the first of the baby boomers has reached retirement in recent years and has been extended to most Western countries where declining fertility rates have made the demographic imbalance between wage earners and retirees even more acute. The impact of an aging population has not gone unnoticed by medical researchers. Increased numbers of elderly are seen as leading to alarming increases in cancer,1 diabetes,2-4
T
Division of Kidney, Urology, and Hematology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD. Address reprint requests to Paul W. Eggers, Program Director for Kidney and Urology Epidemiology, National Institute of Diabetes and Digestive and Kidney Diseases, 6707 Democracy Blvd, Room 615, Bethesda, MD 20892. E-mail: [email protected] 0270-9295/09/$ - see front matter Published by Elsevier Inc. doi:10.1016/j.semnephrol.2009.07.001
urologic diseases,5 osteoporosis,6 need for hip and knee replacements,7 need for long-term care and prescription drug therapy,8,9 overall costs of health care,10 and, of course, end-stage renal disease (ESRD).11 Interestingly, not all predictions are dire. A number of researchers have suggested that the elderly of the future will not have the same levels of disability and disease12,13 as previous generations because of a number of forces such as nutrition, preventive care, and technological interventions.14-16 Early projections of the ESRD program failed to anticipate the expansion of therapy to persons (primarily the elderly and persons with diabetes) that occurred soon after Medicare entitlement began. An early estimate of program growth17 had the program growing to 35,000 within 5 years. In Congressional testimony in 1975, the (then) Department of Health, Education, and Welfare projected a continuing growth of the program up to the range of 50,000 to 60,000 persons.17 By the early 1980s, some projections18,19 suggested that the Medicare ESRD program enrollment would level off at about 90,000, although even without changes in incidence rates, the effect of the aging of the general population would have increased that number to at least 160,000 by the 21st century.17
Seminars in Nephrology, Vol 29, No 6, November 2009, pp 551-554
551
552
P.W. Eggers
Table 1. Projections of the ESRD Population From the US Renal Data System
Source
Projected Year
Incidence
Prevalence
Xue et al20 (2001) ADR (2003) Gilbertson et al22 (2005) ADR (2007) ADR (2008)
2010 2030 2015 2020 2020
129,000 460,000 136,000 144,000 151,000
651,000 2,200,000 700,000 784,000 785,000
More recently, researchers at the coordinating center of the US Renal Data System have published a number of ESRD projections, both in refereed journals and in the Annual Data Report (ADR).20-24 These are summarized in Table 1. With the exception of the 2003 ADR projections, the numbers are fairly consistent, ranging from 130,000 to 150,000 incident cases and 650,000 to 780,000 prevalent cases (combined dialysis and functioning transplant) in the years 2010 to 2020. These are certainly in line with the final incidence (110,000) and prevalence (506,000) counts for 2006.24 Not often noted is the very large estimating error associated with these projections. For example, in the 2007 ADR it is noted that the 144,000 incidence projection for 2020 has a 95% confidence interval of 70,000 to 264,000. The US population is expected to grow by 29% in the 30 years from 2000 to 2030.25 However,
Figure 1. Actual ESRD incident counts for 2005 and projected counts for 2030. Counts for 2030 are estimated sequentially based on (1) census projected population growth; (2) population growth and aging; (3) population growth, aging and changes in racial distribution; and (4) population growth, aging, changes in racial distribution and increased incidence rates. Data taken from the 2003 USRDS ADR and actual counts of patients from the 2008 ADR.
those groups at highest risk of ESRD will increase at much higher rates. The number of people older than the age of 65 will double. In addition, by 2030 racial and ethnic minorities will constitute 42% of the total population, up from 31% in 2000. The 2030 projections often have been cited as a dire warning of what the burden of ESRD could be farther in the future. Figure 1 shows the 2030 projection broken into component parts. Based solely on increased population growth one would expect a 23% increase in ESRD incident cases (131,000) over the 2005 number. The aging of the US population pushes that up to a 53% increase (163,000), and the increased minority composition results in a 65% increase (176,000). However, by far the greatest impact on the 2030 projection is caused by unexplained increases in incidence rates. The reason for the large projected increase from the 2003 ADR can be seen in Figure 2, which is taken from the 2008 ADR and shows
Figure 2. Adjusted total ESRD incidence rates and annual percent of change. Arrows have been added by the author to show straight line trends from 1980 to 2000 and from 2000 through 2006. Reprinted from volume 2 of the 2008 USRDS ADR (Figure 2.3).
Aging pandemic
overall ESRD incident rates from 1980 through 2006, as well as percentage changes from the previous year. In addition, two arrows have been superimposed showing the linear trends in two time periods. The first arrow shows what the trend was from 1980 through 2000 and extended forward. The second arrow shows just the trend from 2000 through 2006. Regardless of the statistical technique used, projections based on data through 2000 (the 2003 ADR projection) are going to have much greater future growth than projections that take into account post-2000 slowing of incidence rates. Will the post-2000 trend in moderate incidence increases continue? There is no way to know. Although the annual increase in the adjusted incident rates between 2001 and 2005 was less than 0.5% per year, the increase from 2005 to 2006 was 2.1%. Therefore, continual updates of the annual rates of ESRD incidence are critical to monitoring future growth projections. Incidence rates have been, and will continue to be, the driving force behind overall growth in the ESRD population. Mortality among dialysis patients is declining, but at a slow rate. Similarly, transplantation has been successful enough so that about 30% of all ESRD patients currently have a functioning kidney graft, up from 27% a decade ago. CHRONIC KIDNEY DISEASE PROGRESSION Much also has been made about the apparent increase in the number of persons with chronic kidney disease (CKD), from 10% of the US population in 1990 to 13% in the early 2000s.26 However, the relationship between CKD burden and subsequent ESRD is not at all clear. First, the huge number of persons with CKD, estimated at 26 million, means that the vast majority of them will not progress to CKD but will die first.27-29 The factors that lead to progression from CKD to ESRD are not well understood. Both sex and race are predictive of progression. Many studies have shown that males show a greater rates of progression than females.30-33 This is shown by the low glomerular filtration rate (estimated glomerular filtration rate ⬍ 60 mL/min/1.73 m2), which is roughly 50% greater among adult women than among adult men, but the rate of ESRD is 50% greater
553
among men. Similarly, the rate of low glomerular filtration rate is higher among whites than among blacks, whereas the rate of ESRD is nearly 4 times as great among blacks. Progression for persons with diabetes is much greater than for persons without diabetes.34 The 2008 ADR shows that the incidence rate of ESRD among persons with diabetes is roughly 8 times as great as the overall ESRD incidence rate.24 Finally, epidemiologic studies examining the overall relationship between changes in the CKD population and change in ESRD incidence find very little positive correlation.34,35 CONCLUSIONS The extension of Medicare coverage to persons with ESRD has been a national experiment in national health insurance for a disease-specific population. The program quickly grew well beyond initial and early expectations. This rapid growth continued for more than a quarter of a century (1973-2000). This has led to fears that this growth will continue unabated until the burden on both the medical community as well as the financial burden on the Medicare program would be unsustainable. Since 2000 the increases have been much more modest, although still greater than the underlying population dynamics would predict. There is little in the previous history to suggest whether the post-2000 slowdown will continue in the near or far future. However, there is no question that population dynamics, particularly increases associated with aging and chronic disease, will push current incidence and prevalence counts to higher levels. REFERENCES 1. Edwards BK, Howe HL, Ries LAG, Thun MJ, Rosenberg HM, Yancik R, et al. Annual report to the nation on the status of cancer, 1973-1999, featuring implications of age and aging on U.S. cancer burden. Cancer. 2002;94:2766-92. 2. Boyle JP, Honeycutt AA, Narayan KM, Hoerger TJ, Geiss LS, Hong C, et al. Projection of diabetes burden through 2050. Diabetes Care. 2001;24:1936-40. 3. Narayan KM, Boyle JP, Geiss LS, Saaddine JB, Thompson TJ. Impact of recent increase in incidence on future diabetes burden. Diabetes Care. 2006;29:2114-6. 4. Mainous AG, Baker R, Koopman RJ, Saxema S, Diaz VA, Everett CJ, et al. Impact of the population at risk
554
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15. 16.
17.
18. 19. 20.
21.
P.W. Eggers
of diabetes on projections of diabetes burden in the United States: an epidemic on the way. Diabetologia. 2007;50:934-40. Litman HJ, McKinlay JB. The future magnitude of urological symptoms in the USA: projections using the Boston Area Community Health survey. BJU Intl. 2007;100:820-5. Burge R, Dawson-Hughes B, Solomon DH, Wong JB, King A, Tosteson A. Incidence and economic burden of osteoporosis-related fractures in the United States, 2005-2025. J Bone Miner Res. 2007;22:465-75. Dixon T, Shaw M, Ebrahim S, Dieppe P. Trends in hip and knee joint replacement: socioeconomic inequalities and projections of need. Ann Rheum Dis. 2004;63:825-30. Lakdwalla D, Goldman DP, Bhattacharya MD, Hurd MD, Joyce GF, Panis CWA. Forecasting the nursing home population. Med Care. 2003;41:8-20. Kildemoes HW, Christiansen T, Gyrd-Hansen D, Kristiansen IS, Andersen M. The impact of population ageing on future Danish drug expenditures. Health Policy. 2006;75:298-311. Garrett N, Marinin EM. The boomers are coming: a total cost of care model of the impact of population aging on the cost of chronic conditions in the United States. Disease Management. 2007;10:51-9. Szczech LA, Lazar IL. Projecting the United States ESRD population: issues regarding treatment of patients with ESRD. Kidney Int Suppl. 2004;90:S3-7. Manton KG. Recent declines in chronic disability in the elderly U.S. population: risk factors and future dynamics. Annu Rev Public Health. 2008;29:91-113. Manton KG, Lamb VL, Gu X. Medicare cost effects of recent disability trends in the elderly: future implications. J Aging Health. 2007;19:359-82. Dormont B, Grignon M, Juber H. Health expenditure growth: reassessing the threat of ageing. Health Economics. 2006;15:947-63. Stock GB. The pitfalls of planning of demographic change. Ann N Y Acad Sci. 2004;1019:546-51. Chernichovsky D, Markowitz S. Aging and aggregate costs of medical care: conceptual and policy issues. Health Econ. 2004;13:543-62. Eggers PW, Connerton R, McMullan M. The Medicare experience with end-stage renal disease: trends in incidence, prevalence, and survival. Health Care Financing Rev. 1984;5:69-88. Iglehard JK. Funding the end-stage renal disease program. N Engl J Med. 1982;306:492-6. Kolata GB. NMC thrives selling dialysis. Science. 1980;208:25. Xue JL, Ma JZ, Louis TA, Collins AJ. Forecast of the number of patients with end-stage renal disease in the United States to the year 2010. J Am Soc Nephrol. 2001;12:2753-8. US Renal Data System. USRDS 2003 annual data report. Bethesda: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2003.
22. Gilbertson DT, Liu J, Xue JL, Louis TA, Solid GA, Ebben JP, et al. Projecting the number of patients with end-stage renal disease in the United States to the year 2015. J Am Soc Nephrol. 2005;16:3736-41. 23. US Renal Data System. USRDS 2007 annual data report. Bethesda: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2007. 24. US Renal Data System. USRDS 2008 annual data report. Bethesda: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2008. 25. Day JC. Population projections of the United States by age, sex, race, and Hispanic origin: 1995 to 2020, U.S. Bureau of the Census, current population reports, P25-1130. Washington, DC: U.S. Government Printing Office; 1996. 26. Coresh JC, Selvin E, Stevens LA, Manzi J, Kusek JW, Eggers PW, et al. Prevalence of chronic kidney disease in the United States. JAMA. 2007;298:2038-47. 27. Foley RN, Murray AM, Herzog CA, McBean AM, Eggers PW, Collins AJ. Chronic kidney disease and the risk for cardiovascular disease, renal replacement therapy, and death in the United States Medicare population, 1998 to 1999. J Am Soc Nephrol. 2005;16:489-95. 28. O’Hare AM, Choi AI, Bertenthal D, Bacchetti P, Garg AX, Kaufman JS, et al. Age affects outcomes in chronic kidney disease. J Am Soc Nephrol. 2007;18: 2758-65. 29. Erikson BO, Ingebretsen OC. The progression of chronic kidney disease: a 10 year population based study of the effects of gender and age. Kidney Int. 2006;69:375-82. 30. Choukroun G, Itakura Y, Albouze G, Christophe J, Man NK, Grunfeld JP, et al. Factors influencing progression of renal failure in autosomal dominant polycystic kidney disease. J Am Soc Nephrol. 1995;6: 1634-42. 31. Coggins CH, Lewis JB, Caggiula AW, Castaldo LS, Klahr S, Wang S. Differences between women and men with chronic renal disease. Nephrol Dial Transplant. 1998; 13:1430-7. 32. Neugarten J, Acharya A, Silbiger SR. Effect of gender on the progression of nondiabetic renal disease: a meta-analysis. J Am Soc Nephrol. 2000;11:319-29. 33. Berg UB. Differences in decline in GFR with age between males and females, reference data on clearances of inulin and PAH in potential kidney donors. Nephrol Dial Transplant. 2006;21:2577-82. 34. Hsu CY, Lin L, Shlipak MG. The incidence of end-stage is increasing faster than the prevalence of chronic renal insufficiency. Ann Intern Med. 2004;141:95-101. 35. Hsu CY, Go AS, McCulloch CE, Darbinian J, Iribarren C. Exploring secular trends in the likelihood of receiving treatment for end-stage renal disease. Can J Am Soc Nephrol. 2007;2:81-8.
he presence of the baby boomer bulge in the US population caused by the post– World War II spike in fertility has been the subject of demographic study for decades as the baby boomers moved through childhood, college years, and early adulthood (producing a smaller baby boomer echo of children). Beginning in the 1970s there has been a decline in the overall fertility rate. This, combined with the impending retirement of the baby boomer population has led to continual debates in Congress about the implications for the solvency of the Social Security and Medicare trust funds. This debate has become even more urgent as the first of the baby boomers has reached retirement in recent years and has been extended to most Western countries where declining fertility rates have made the demographic imbalance between wage earners and retirees even more acute. The impact of an aging population has not gone unnoticed by medical researchers. Increased numbers of elderly are seen as leading to alarming increases in cancer,1 diabetes,2-4
T
Division of Kidney, Urology, and Hematology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD. Address reprint requests to Paul W. Eggers, Program Director for Kidney and Urology Epidemiology, National Institute of Diabetes and Digestive and Kidney Diseases, 6707 Democracy Blvd, Room 615, Bethesda, MD 20892. E-mail: [email protected] 0270-9295/09/$ - see front matter Published by Elsevier Inc. doi:10.1016/j.semnephrol.2009.07.001
urologic diseases,5 osteoporosis,6 need for hip and knee replacements,7 need for long-term care and prescription drug therapy,8,9 overall costs of health care,10 and, of course, end-stage renal disease (ESRD).11 Interestingly, not all predictions are dire. A number of researchers have suggested that the elderly of the future will not have the same levels of disability and disease12,13 as previous generations because of a number of forces such as nutrition, preventive care, and technological interventions.14-16 Early projections of the ESRD program failed to anticipate the expansion of therapy to persons (primarily the elderly and persons with diabetes) that occurred soon after Medicare entitlement began. An early estimate of program growth17 had the program growing to 35,000 within 5 years. In Congressional testimony in 1975, the (then) Department of Health, Education, and Welfare projected a continuing growth of the program up to the range of 50,000 to 60,000 persons.17 By the early 1980s, some projections18,19 suggested that the Medicare ESRD program enrollment would level off at about 90,000, although even without changes in incidence rates, the effect of the aging of the general population would have increased that number to at least 160,000 by the 21st century.17
Seminars in Nephrology, Vol 29, No 6, November 2009, pp 551-554
551
552
P.W. Eggers
Table 1. Projections of the ESRD Population From the US Renal Data System
Source
Projected Year
Incidence
Prevalence
Xue et al20 (2001) ADR (2003) Gilbertson et al22 (2005) ADR (2007) ADR (2008)
2010 2030 2015 2020 2020
129,000 460,000 136,000 144,000 151,000
651,000 2,200,000 700,000 784,000 785,000
More recently, researchers at the coordinating center of the US Renal Data System have published a number of ESRD projections, both in refereed journals and in the Annual Data Report (ADR).20-24 These are summarized in Table 1. With the exception of the 2003 ADR projections, the numbers are fairly consistent, ranging from 130,000 to 150,000 incident cases and 650,000 to 780,000 prevalent cases (combined dialysis and functioning transplant) in the years 2010 to 2020. These are certainly in line with the final incidence (110,000) and prevalence (506,000) counts for 2006.24 Not often noted is the very large estimating error associated with these projections. For example, in the 2007 ADR it is noted that the 144,000 incidence projection for 2020 has a 95% confidence interval of 70,000 to 264,000. The US population is expected to grow by 29% in the 30 years from 2000 to 2030.25 However,
Figure 1. Actual ESRD incident counts for 2005 and projected counts for 2030. Counts for 2030 are estimated sequentially based on (1) census projected population growth; (2) population growth and aging; (3) population growth, aging and changes in racial distribution; and (4) population growth, aging, changes in racial distribution and increased incidence rates. Data taken from the 2003 USRDS ADR and actual counts of patients from the 2008 ADR.
those groups at highest risk of ESRD will increase at much higher rates. The number of people older than the age of 65 will double. In addition, by 2030 racial and ethnic minorities will constitute 42% of the total population, up from 31% in 2000. The 2030 projections often have been cited as a dire warning of what the burden of ESRD could be farther in the future. Figure 1 shows the 2030 projection broken into component parts. Based solely on increased population growth one would expect a 23% increase in ESRD incident cases (131,000) over the 2005 number. The aging of the US population pushes that up to a 53% increase (163,000), and the increased minority composition results in a 65% increase (176,000). However, by far the greatest impact on the 2030 projection is caused by unexplained increases in incidence rates. The reason for the large projected increase from the 2003 ADR can be seen in Figure 2, which is taken from the 2008 ADR and shows
Figure 2. Adjusted total ESRD incidence rates and annual percent of change. Arrows have been added by the author to show straight line trends from 1980 to 2000 and from 2000 through 2006. Reprinted from volume 2 of the 2008 USRDS ADR (Figure 2.3).
Aging pandemic
overall ESRD incident rates from 1980 through 2006, as well as percentage changes from the previous year. In addition, two arrows have been superimposed showing the linear trends in two time periods. The first arrow shows what the trend was from 1980 through 2000 and extended forward. The second arrow shows just the trend from 2000 through 2006. Regardless of the statistical technique used, projections based on data through 2000 (the 2003 ADR projection) are going to have much greater future growth than projections that take into account post-2000 slowing of incidence rates. Will the post-2000 trend in moderate incidence increases continue? There is no way to know. Although the annual increase in the adjusted incident rates between 2001 and 2005 was less than 0.5% per year, the increase from 2005 to 2006 was 2.1%. Therefore, continual updates of the annual rates of ESRD incidence are critical to monitoring future growth projections. Incidence rates have been, and will continue to be, the driving force behind overall growth in the ESRD population. Mortality among dialysis patients is declining, but at a slow rate. Similarly, transplantation has been successful enough so that about 30% of all ESRD patients currently have a functioning kidney graft, up from 27% a decade ago. CHRONIC KIDNEY DISEASE PROGRESSION Much also has been made about the apparent increase in the number of persons with chronic kidney disease (CKD), from 10% of the US population in 1990 to 13% in the early 2000s.26 However, the relationship between CKD burden and subsequent ESRD is not at all clear. First, the huge number of persons with CKD, estimated at 26 million, means that the vast majority of them will not progress to CKD but will die first.27-29 The factors that lead to progression from CKD to ESRD are not well understood. Both sex and race are predictive of progression. Many studies have shown that males show a greater rates of progression than females.30-33 This is shown by the low glomerular filtration rate (estimated glomerular filtration rate ⬍ 60 mL/min/1.73 m2), which is roughly 50% greater among adult women than among adult men, but the rate of ESRD is 50% greater
553
among men. Similarly, the rate of low glomerular filtration rate is higher among whites than among blacks, whereas the rate of ESRD is nearly 4 times as great among blacks. Progression for persons with diabetes is much greater than for persons without diabetes.34 The 2008 ADR shows that the incidence rate of ESRD among persons with diabetes is roughly 8 times as great as the overall ESRD incidence rate.24 Finally, epidemiologic studies examining the overall relationship between changes in the CKD population and change in ESRD incidence find very little positive correlation.34,35 CONCLUSIONS The extension of Medicare coverage to persons with ESRD has been a national experiment in national health insurance for a disease-specific population. The program quickly grew well beyond initial and early expectations. This rapid growth continued for more than a quarter of a century (1973-2000). This has led to fears that this growth will continue unabated until the burden on both the medical community as well as the financial burden on the Medicare program would be unsustainable. Since 2000 the increases have been much more modest, although still greater than the underlying population dynamics would predict. There is little in the previous history to suggest whether the post-2000 slowdown will continue in the near or far future. However, there is no question that population dynamics, particularly increases associated with aging and chronic disease, will push current incidence and prevalence counts to higher levels. REFERENCES 1. Edwards BK, Howe HL, Ries LAG, Thun MJ, Rosenberg HM, Yancik R, et al. Annual report to the nation on the status of cancer, 1973-1999, featuring implications of age and aging on U.S. cancer burden. Cancer. 2002;94:2766-92. 2. Boyle JP, Honeycutt AA, Narayan KM, Hoerger TJ, Geiss LS, Hong C, et al. Projection of diabetes burden through 2050. Diabetes Care. 2001;24:1936-40. 3. Narayan KM, Boyle JP, Geiss LS, Saaddine JB, Thompson TJ. Impact of recent increase in incidence on future diabetes burden. Diabetes Care. 2006;29:2114-6. 4. Mainous AG, Baker R, Koopman RJ, Saxema S, Diaz VA, Everett CJ, et al. Impact of the population at risk
554
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15. 16.
17.
18. 19. 20.
21.
P.W. Eggers
of diabetes on projections of diabetes burden in the United States: an epidemic on the way. Diabetologia. 2007;50:934-40. Litman HJ, McKinlay JB. The future magnitude of urological symptoms in the USA: projections using the Boston Area Community Health survey. BJU Intl. 2007;100:820-5. Burge R, Dawson-Hughes B, Solomon DH, Wong JB, King A, Tosteson A. Incidence and economic burden of osteoporosis-related fractures in the United States, 2005-2025. J Bone Miner Res. 2007;22:465-75. Dixon T, Shaw M, Ebrahim S, Dieppe P. Trends in hip and knee joint replacement: socioeconomic inequalities and projections of need. Ann Rheum Dis. 2004;63:825-30. Lakdwalla D, Goldman DP, Bhattacharya MD, Hurd MD, Joyce GF, Panis CWA. Forecasting the nursing home population. Med Care. 2003;41:8-20. Kildemoes HW, Christiansen T, Gyrd-Hansen D, Kristiansen IS, Andersen M. The impact of population ageing on future Danish drug expenditures. Health Policy. 2006;75:298-311. Garrett N, Marinin EM. The boomers are coming: a total cost of care model of the impact of population aging on the cost of chronic conditions in the United States. Disease Management. 2007;10:51-9. Szczech LA, Lazar IL. Projecting the United States ESRD population: issues regarding treatment of patients with ESRD. Kidney Int Suppl. 2004;90:S3-7. Manton KG. Recent declines in chronic disability in the elderly U.S. population: risk factors and future dynamics. Annu Rev Public Health. 2008;29:91-113. Manton KG, Lamb VL, Gu X. Medicare cost effects of recent disability trends in the elderly: future implications. J Aging Health. 2007;19:359-82. Dormont B, Grignon M, Juber H. Health expenditure growth: reassessing the threat of ageing. Health Economics. 2006;15:947-63. Stock GB. The pitfalls of planning of demographic change. Ann N Y Acad Sci. 2004;1019:546-51. Chernichovsky D, Markowitz S. Aging and aggregate costs of medical care: conceptual and policy issues. Health Econ. 2004;13:543-62. Eggers PW, Connerton R, McMullan M. The Medicare experience with end-stage renal disease: trends in incidence, prevalence, and survival. Health Care Financing Rev. 1984;5:69-88. Iglehard JK. Funding the end-stage renal disease program. N Engl J Med. 1982;306:492-6. Kolata GB. NMC thrives selling dialysis. Science. 1980;208:25. Xue JL, Ma JZ, Louis TA, Collins AJ. Forecast of the number of patients with end-stage renal disease in the United States to the year 2010. J Am Soc Nephrol. 2001;12:2753-8. US Renal Data System. USRDS 2003 annual data report. Bethesda: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2003.
22. Gilbertson DT, Liu J, Xue JL, Louis TA, Solid GA, Ebben JP, et al. Projecting the number of patients with end-stage renal disease in the United States to the year 2015. J Am Soc Nephrol. 2005;16:3736-41. 23. US Renal Data System. USRDS 2007 annual data report. Bethesda: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2007. 24. US Renal Data System. USRDS 2008 annual data report. Bethesda: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2008. 25. Day JC. Population projections of the United States by age, sex, race, and Hispanic origin: 1995 to 2020, U.S. Bureau of the Census, current population reports, P25-1130. Washington, DC: U.S. Government Printing Office; 1996. 26. Coresh JC, Selvin E, Stevens LA, Manzi J, Kusek JW, Eggers PW, et al. Prevalence of chronic kidney disease in the United States. JAMA. 2007;298:2038-47. 27. Foley RN, Murray AM, Herzog CA, McBean AM, Eggers PW, Collins AJ. Chronic kidney disease and the risk for cardiovascular disease, renal replacement therapy, and death in the United States Medicare population, 1998 to 1999. J Am Soc Nephrol. 2005;16:489-95. 28. O’Hare AM, Choi AI, Bertenthal D, Bacchetti P, Garg AX, Kaufman JS, et al. Age affects outcomes in chronic kidney disease. J Am Soc Nephrol. 2007;18: 2758-65. 29. Erikson BO, Ingebretsen OC. The progression of chronic kidney disease: a 10 year population based study of the effects of gender and age. Kidney Int. 2006;69:375-82. 30. Choukroun G, Itakura Y, Albouze G, Christophe J, Man NK, Grunfeld JP, et al. Factors influencing progression of renal failure in autosomal dominant polycystic kidney disease. J Am Soc Nephrol. 1995;6: 1634-42. 31. Coggins CH, Lewis JB, Caggiula AW, Castaldo LS, Klahr S, Wang S. Differences between women and men with chronic renal disease. Nephrol Dial Transplant. 1998; 13:1430-7. 32. Neugarten J, Acharya A, Silbiger SR. Effect of gender on the progression of nondiabetic renal disease: a meta-analysis. J Am Soc Nephrol. 2000;11:319-29. 33. Berg UB. Differences in decline in GFR with age between males and females, reference data on clearances of inulin and PAH in potential kidney donors. Nephrol Dial Transplant. 2006;21:2577-82. 34. Hsu CY, Lin L, Shlipak MG. The incidence of end-stage is increasing faster than the prevalence of chronic renal insufficiency. Ann Intern Med. 2004;141:95-101. 35. Hsu CY, Go AS, McCulloch CE, Darbinian J, Iribarren C. Exploring secular trends in the likelihood of receiving treatment for end-stage renal disease. Can J Am Soc Nephrol. 2007;2:81-8.