Two: Incidence & prevalence
Growth of the end-stage renal disease (ESRD) program is typically characterized by assessment of total patient counts at a single point in time (point prevalence), of new cases accepted for treatment (incidence), and of patients receiving kidney transplants. Disease rates are computed based on the number of patients per million people in the general population, and are adjusted for age, gender, and race.
In the 2007 ADR we updated projections for the ESRD program to the year 2020. We repeat the projections this year, updating data on absolute patient counts to show how these counts may differ from the projections over time. (Patient counts are revised each year, with slight changes occurring as networks reconcile the data given to CMS.) Growth in the incident population in 2006 was greater than predicted, at 3.4 instead of 2.5 percent. The USRDS Coordinating Center has carefully evaluated this increase, and has confirmed that data are from the most up-to-date SIMS registration files. Several additional years of data will be required to determine if this increase represents the beginning of a trend. Projections looking at dialysis modality are more complex, and we will assess them further in the 2009 ADR.
Concurrent with the unexpected rise in patient counts, rates of ESRD incidence have also grown, reaching 360 per million population in 2006 — a new high for the U.S. ESRD program. Again, it is not clear if this change will be sustained in the future; 3–4 more years of data will be required before a clear trend can be established. Between 2005 and 2006, the greatest increase in counts of new ESRD patients occurred among those age 20–44, 45–64 and 65–74, at 2.7, 6.1, and 3.5 percent, respectively. For each of these groups, this is the highest growth seen in the last five years.
The median age of new patients beginning ESRD therapy is now 64.4. Since 2000, the adjusted incident rate for patients age 45–64 has increased 2.4 percent, to 625 per million population. The rate for those age 75 and older, in contrast, has grown 11 percent, to 1,744, while patients age 20–44 have seen an increase of 6.1 percent, to 127.
Racial and ethnic discrepancies in ESRD persist, with 2006 rates in the African American and Native American populations 3.6 and 1.8 times greater, respectively, than the rate among whites, and the rate in the Hispanic population 1.5 times higher than that of non-Hispanics.
The adjusted rate of incident ESRD cases due to diabetes increased 2.5 percent in 2006, to 159 per million population, while the rate of ESRD caused by glomerulonephritis continues to fall from its peak of 33 in the late 1990s, reaching 26 per million population in 2006.
Even after adjustments for age and gender, rates of ESRD continue to vary widely across the U.S. This year we update our data on ESRD in the major metropolitan statistical areas (MSAs) of the United States. Among African Americans, for instance, the incidence of ESRD is greatest in the Pittsburgh, Pennsylvania area, while for Hispanics it is highest in the Minneapolis/St. Paul MSA. These variations may reflect different burdens of chronic kidney disease, as well as regional differences in the use of detection efforts and treatment interventions in populations at risk for kidney failure.
The prevalent population age 75 and older has more than doubled since 1996, while the number of patients age 45–64 has grown 87 percent. The population age 20–44, in contrast, is just 18.5 percent larger now than a decade ago. Rates per million population are growing most quickly among patients age 65 and older, with an overall increase of 20–24 percent since 2000, and of 48 and 65 percent for ages 65–74, and 75 and older, respectively, in the past decade. Regional variations in ESRD prevalence reflect differences in adjusted survival, in part related to higher rates of transplantation in certain areas of the U.S.
Still to be determined is whether these data reflect short- or long-term trends, as the emergence of the baby boomers into a senior population will continue to contribute to the growth of the overall ESRD population, even with moderations in disease rates. The growth of diabetes in both the general Medicare population and among younger patients is a concern as well.
figure 2.3 In 2006, the adjusted incident rate of ESRD reached 360 per million population. The growth of 2.1 percent over the 2005 rate followed four years in which the one-year change was lower than 1 percent, and is the highest seen since 1999.
figure 2.4 The greatest incident rates of ESRD per million population continue to occur in the most populated areas of the country — the eastern and southern states, and parts of the Upper Midwest. Rates have changed little since 1996 in the Northwest, Rocky Mountain states, southern Florida, and northern New England.
figures 2.5, 2.6, 2.7, & 2.8 Since 2000, the adjusted incident rate of ESRD has increased 11.0 percent for patients age 75 and older, reaching 1,744 per million population in 2006, while the rate for those age 20–44 has grown 6.1 percent, to 127. Growth in the rate has been lower for other ages, at 3.2 percent or less since 2000. By race, the incident rates for African Americans and Native Americans in 2006 reached 1,010 and 489, respectively — 3.6 and 1.8 times greater than the rate for white patients. A similar discrepancy is seen among Hispanics, for whom the 2006 rate of 520 per million population is 1.5 times greater than the rate of 347 among non-Hispanics. The number of patients with diabetes as the primary cause of ESRD reached 48,157 in 2006, 4.6 percent greater than in the previous year, and 17.2 percent higher than in 2000. Incident rates for these patients have grown 3.7 percent since 2000, to reach 159 per million population. The incident rate of ESRD due to glomerulonephritis, in contrast, continues to fall — 15.6 percent since 2000, to reach 26 per million population.
figure 2.9 The incident rate among patients with Medicare Advantage (formerly Medicare + Choice) coverage peaked in 2001 at 1,499 per million population, and since then has declined by 6 percent to a rate of 1,404 in 2005. This 2005 rate is 35 percent lower than the 2005 rate of 2,162 found in patients with fee-for-service coverage.
figure 2.10 The median age of the incident ESRD population has changed little since the late 1990s, and in 2006 was 64.4 overall, with a range from 57.6 in Native Americans to 67.1 in whites.
figure 2.11 The prevalent rate of ESRD, adjusted for age, gender, and race, rose 2.3 percent between 2005 and 2006 to reach 1,626 per million population. This is 15 percent higher than in 2000, but the rate of growth seems to have stabilized, remaining at 2.0–2.6 percent since 2002.
figure 2.12 Since 1996, prevalent rates have increased across most of the United States, with the exception of the Rocky Mountain states, areas of the Plains states, Florida, and parts of New England.
figures 2.13, 2.14, 2.15, & 2.16 In 2006, the prevalent rate of ESRD among patients age 65–74 reached 5,700 per million population — an increase of 20.3 percent since 2000, and of 48 percent since 1996. For patients age 75 and older the rate is now nearing 5,000 per million population, 23.6 percent greater than in 2000. By race, prevalent rates of ESRD continue to be highest in the African American and Native American populations, at 5,004 and 2,691 per million population, respectively, in 2006, compared to 1,194 among whites and 1,831 among Asians. And the rate for Hispanic patients reached 2,326 in 2006, 1.5 times greater than the rate of 1,576 seen in the non-Hispanic population. Growth in prevalent rates by primary diagnosis has been relatively stable over the past two years, at 2.3–2.8 percent for diabetes, 1.5–1.6 percent for hypertension, 0.4–0.5 percent for glomerulonephritis, and 2.7–3.2 percent for cystic kidney disease. Rates range from a low of 76.7 for cystic kidney disease to a high of 604 for diabetes.
figure 2.17 The median age of the prevalent ESRD population is now 58.8 years. It varies little by race or ethnicity, ranging from 56.9 in the African American population to 60.0 among whites.
table 2.a By metropolitan stastistical area (MSA), the greatest prevalent rates of ESRD for whites occur in the Los Angeles area, at 1,513 per million population. For African Americans, in contrast, the highest prevalence occurs in the East and Midwest, with rates exceeding 5,300 per million population in the Minneapolis/St. Paul, St. Louis, Cincinnati, Cleveland, and Pittsburgh areas. The greatest prevalence of ESRD in the Hispanic population occurs in the St. Louis MSA — at nearly 5,200, it is almost twice the next highest rate of 2,658, found in the San Diego area.
figures 2.18, 2.19, & 2.20 The overall rate of new ESRD cases due to diabetes was 159 per million population in 2006, 50 percent higher than a decade before. Both the highest rate and the greatest growth occurred in Network 14, at 206 per million and 76 percent, respectively. The rate of new ESRD cases due to hypertension rose most in Network 15, at 83 percent, but reached only 55 per million population, one of the lowest network rates. The highest rate, of 142, occurred in Network 8, and was 54 percent greater than in 1996. Rates of ESRD due to glomerulonephritis have fallen 8.2 percent overall since 1996, and 18–23 percent in Networks 4, 7, and 10.
figure 2.21 The mean age of both the incident and prevalent ESRD populations is greatest in the Upper Midwest, the Northeast, and Florida. In the lower quintile the mean age is 60.2 for incident patients, compared to 56.5 in the prevalent population. Means in the upper quintile are 65.6 and 59.9, respectively.
tables 2.b, 2.c, & 2.d These tables present adjsuted patient demographics and disease rates by modality and ESRD network. With an overall incident rate for dialysis patients of 352 per million population in 2006, rates by network range from 219 in Network 16 to 422 in Network 8. The distribution of patients by race varies widely. African Americans, for example, make up just 6.5 percent of the incident dialysis population in the northwestern states covered by Network 16, but 56 percent in Network 6, which encompasses the southern states of Georgia, North Carolina, and South Carolina. The overall 2006 prevalent rate for dialysis patients is 1,140 per million population, but rates by network range from 696 in Network 16 to nearly 1,460 in Network 6. Differences in the distribution of patients by race are equally pronounced in the prevalent population. African Americans account for fewer than one in ten patients in Network 16, but more than two of three patients in Network 6. The prevalent transplant rate is lowest in Network 6, at 379 per million population. Patients residing in the Midwestern states covered by Network 11 have the highest rate, at 744 per million population — 12.4 percent greater than the next highest rate of 661, found in Network 4. And while Network 11 accounts for just 6.9 and 6.3 percent of the incident and prevalent dialysis populations, 11.1 percent of all prevalent transplant patients in the U.S. live in the states it covers.
all figures incident ESRD patients. • figure 2.3 rates adjusted for age, gender, & race. figure 2.4 by HSA; adjusted for age, gender, & race. Excludes patients residing in Puerto Rico & the Territories. For details on how to read the map legends, please see page xvi in the Introduction. figure 2.5 rates adjusted for gender & race. figures 2.6–7 rates adjusted for age & gender. figure 2.8 rates adjusted for age, gender, & race. figure 2.9 unadjusted. • For Hispanic patients we present data beginning in 1996, the first full year after the April 1995 introduction of the revised Medical Evidence form, which contains more specific questions on race & ethnicity.
all figures December 31 point prevalent ESRD patients. • figure 2.11 rates adjusted for age, gender, & race. figure 2.12 by HSA; adjusted for age, gender, & race. Excludes patients residing in Puerto Rico & the Territories. For details on how to read the map legends, please see page xvi in the Introduction. figure 2.13 rates adjusted for gender & race. figures 2.14–15 rates adjusted for age & gender. figure 2.16 rates adjusted for age, gender, & race. table 2.a incident & December 31 point prevalent ESRD patients, 2006. Adjusted for age & gender. • For Hispanic patients we present data beginning in 1996, the first full year after the April 1995 introduction of the revised Medical Evidence form, which contains more specific questions on race & ethnicity.
figures 2.18–20 incident ESRD patients; rates adjusted for age, gender, & race. figure 2.21 incident & December 31 point prevalent ESRD patients, 2006, by HSA, unadjusted. Excludes patients residing in Puerto Rico & the Territories. For details on how to read the map legends, please see page xvi in the Introduction. table 2.b incident dialysis patients. table 2.c December 31 point prevalent dialysis patients. table 2.d December 31 point prevalent transplant patients. • tables 2.b–d counts & percentages include all patients in each network; rates, however, are calculated for the U.S. population only, & exclude patients with unknown age, gender, race, or network. Rates adjusted for age, gender, & race. * Values for cells with ten or fewer patients are suppressed. • A list of network contacts can be found at the beginning of Appendix A.