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  Figure 3.1 All-cause rehospitalization or death within 30 days after live hospital discharge in the general Medicare (no CKD), CKD, & hemodialysis populations, age 66+, 2010
  Figure 3.2 Adjusted hospitalization rates in Medicare patients, by comorbidity & CKD diagnosis code, 2010
  Figure 3.3 Adjusted hospitalization rates in Medicare patients, by race & CKD diagnosis code, 2010
  Figure 3.4 Adjusted all-cause hospitalization rates, by dataset & CKD diagnosis code, 2010
  Figure 3.5 Adjusted rates of hospitalization for cardiovascular disease, by dataset & CKD diagnosis code, 2010
  Figure 3.6 Adjusted rates of hospitalization for infection, by dataset & CKD diagnosis code, 2010
  Figure 3.7 Adjusted rates of hospitalization for other causes, by dataset & CKD diagnosis code, 2010
  Figure 3.8 Adjusted all-cause rehospitalization or death 30 days after live hospital discharge in CKD patients
  Figure 3.9 All-cause rehospitalization or death within 30 days after discharge from all-cause index hospitalization, by CKD stage, 2010
  Figure 3.10 All-cause rehospitalization or death within 30 days after discharge from cardiovascular index hospitalization, by CKD stage, 2010
  Figure 3.11 All-cause rehospitalization or death 30 days after live hospital discharge in Medicare patients, by age & CKD diagnosis code, 2010
  Figure 3.12 All-cause rehospitalization or death 30 days after live hospital discharge in Medicare patients, by race & CKD diagnosis code, 2010
  Figure 3.13 All-cause rehospitalization or death 30 days after live hospital discharge during the transition to ESRD, by cause-specific index hospitalization, 2010
  Figure 3.14 All-cause mortality rates in Medicare CKD & non-CKD patients
  Figure 3.15 All-cause mortality rates in Medicare CKD & non-CKD patients, by CKD diagnosis code, 2010
  Figure 3.16 Adjusted mortality rates in Medicare patients, by comorbidity & CKD diagnosis code, 2010
  Figure 3.17 Adjusted mortality rates in Medicare patients, by race & CKD diagnosis code, 2010
  Table 3.a Adjusted hospitalization rates (per 1,000 patient years) in Medicare patients, by CKD diagnosis code, 2010c
  Table 3.b Percent live hospital discharges in CKD patients with an all-cause rehospitalization within 30 days, 2010
  Table 3.c Adjusted mortality rates (per 1,000 patient years at risk) in Medicare patients, by CKD diagnosis code, 2010
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Chapter 3

Morbidity & mortality in patients with CKD

Introduction

Assessing morbidity in patients with chronic kidney disease requires longitudinal data from a defined population, with relatively complete information on all-cause and cause-specific hospitalization. Such data are rarely available on a random sample of the U.S. population, since it is very difficult to track patients across multiple insurers. Health plan datasets from Medicare and from employer group health plans (EGHPs), however, can capture information well, particularly over a one-year period, and they provide a unique opportunity to assess morbidity.

In this chapter we use data from three insurers which represent large populations. Medicare data, for instance, cover 95 percent of individuals age 65 and older. We also employ the Thomson Rueters MarketScan dataset and the United Healthcare Ingenix i3 LabRx dataset, both from large EGHPs. MarketScan data cover health plan expenditure claims for employers that are approximately 80 percent self-insured, compared to just 20 percent in the Ingenix i3 data. For each dataset we use diagnosis codes to define CKD during a one-year entry period, noting hospitalizations and services in the one-year follow-up period.

We begin by examining rehospitalization rates in the CKD, hemodialysis, and general Medicare populations. Thirty-four percent of hemodialysis patients are rehospitalized within 30 days, compared to 24 percent of patients with CKD and 18 percent in the general Medicare population. Rehospitalization rates have not changed in the past decade, a major concern. Detailed causes of rehospitalizations need to be addressed and to be matched up with the changes in medication use (reported in Chapter Two), with particular reference to the decreased use of ACE/ARBs and diuretics.

Overall, the rate of hospitalizations approaches 0.6 per patient year, a rate less than half of that noted for hemodialysis patients (see Chapter Three of Volume Two). Rates of hospitalization for cardiovascular disease and infection continue to rise with CKD stage, an observation reported by other investigators more than seven years ago.

Data on mortality in CKD and non-CKD patients illustrate the impact of adjustments for comorbidity and disease severity on absolute death rates. Adjusting for age, gender, race, comorbidity, and prior hospitalizations, mortality among CKD patients in 2010 is 59 percent greater than among non-CKD patients. As with hospitalization, CKD is thus a risk multiplier for mortality. The decline in rates since 1995 may partially reflect increased recognition of CKD, as illustrated by the increasing percentage of patients carrying the diagnosis; it may also indicate classification bias rather than a true reduction. Adjustments over time, however, appear to mitigate some of these issues, as the drop in mortality rates since 1995 is greater than that seen among patients without CKD.

Patterns in mortality by CKD stage parallel those seen with hospitalization; the adjusted rate in patients with CKD of Stages 4–5, for example, is 53 percent greater than that in non-CKD patients. The impact of diabetes and congestive heart failure as risk multipliers is also important, particularly given that cardiovascular risk factors are relatively under-treated in U.S. patients with CKD.

Figure 3.1 All-cause rehospitalization or death within 30 days after live hospital discharge in the general Medicare (no CKD), CKD, & hemodialysis populations, age 66+, 2010 (see page 142 for analytical methods. January 1, 2010 point prevalent Medicare patients, age 66 & older on December 31, 2009, unadjusted. Includes live hospital discharges from January 1 to December 1, 2010.)

Hospitalization rates in CKD & non-CKD patients

Figure 3.2 Adjusted hospitalization rates in Medicare patients, by comorbidity & CKD diagnosis code, 2010

In both CKD and non-CKD populations age 66 and older, adjusted rates of hospitalization increase with greater comorbidity. In 2010, for example, admissions for Stage 4–5 CKD patients with both diabetes and cardiovascular disease reached 882 per 1,000 patient years — more than twice the rate among patients with neither diagnosis. January 1, 2010 point prevalent Medicare patients, age 66 & older on December 31, 2009. Adjusted for age/gender/race/prior hospitalization/comorbidity; rates by one factor are adjusted for the others. Ref: Medicare patients age 66 & older, 2010.

Figure 3.3 Adjusted hospitalization rates in Medicare patients, by race & CKD diagnosis code, 2010

By race, hospitalization rates are generally higher among blacks/African Americans compared to whites, but differences are negligible in those with Stage 4–5 CKD, at 598 and 596 per 1,000 patient years, respectively. January 1, 2010 point prevalent Medicare patients, age 66 & older on December 31, 2009. Adjusted for age/gender/race/prior hospitalization/comorbidity; rates by one factor are adjusted for the others. Ref: Medicare patients age 66 & older, 2010.

Table 3.a Adjusted hospitalization rates (per 1,000 patient years) in Medicare patients, by CKD diagnosis code, 2010

Among Medicare patients age 66 and older, adjusted admission rates are greater for patients with CKD compared to those without, and for patients with Stage 4–5 CKD compared to those in an earlier stage. The highest rates by race occur among blacks/African Americans; by gender, admissions for women with CKD are consistently higher than those found in their male counterparts. January 1, 2010 point prevalent Medicare patients, age 66 & older on December 31, 2009. Adj: age/gender/race/prior hospitalization/comorbidity; rates by one factor are adjusted for the others. Ref: Medicare patients age 66 & older, 2010.

Figure 3.4 Adjusted all-cause hospitalization rates, by dataset & CKD diagnosis code, 2010

Adjusted all-cause hospitalization rates,are higher among Medicare patients age 66 and older than in the younger MarketScan and Ingenix i3 populations. Rates are also greatest for patients with CKD compared to those without, and are generally higher in the later stages of the disease. All-cause hospitalization rates, for example, are 58 percent higher among Medicare patients with Stage 4–5 CKD than among their counterparts with Stages 1–2, reaching 589 admissions per 1,000 patient years; in the MarketScan and Ingenix i3 populations, rates are 63 and 67 percent higher in those with later-stage CKD. Medicare: point prevalent patients on January 1, 2010, age 66 & older on December 31, 2009. MarketScan & Ingenix i3: point prevalent patients on January 1, 2010, age 50–64 on December 31, 2009. Adjusted for gender/prior hospitalization/comorbidity; ref: Medicare patients age 66 & older, 2010.

Figure 3.5 Adjusted rates of hospitalization for cardiovascular disease, by dataset & CKD diagnosis code, 2010

Adjusted rates of hospitalization for cardiovascular disease,are higher among Medicare patients age 66 and older than in the younger MarketScan and Ingenix i3 populations. Rates are also greatest for patients with CKD compared to those without, and are generally higher in the later stages of the disease. Among Medicare patients, the rate of 182 cardiovascular admissions per 1,000 patient years in those with Stage 4–5 CKD is 86 percent higher than the rate of 98 reported for those with CKD of Stages 1–2. And rates of 129 and 107 reported for MarketScan and Ingenix i3 patients with later-stage CKD are 112 and 65 percent greater, respectively, than those for patients in the earliest stages of the disease. Medicare: point prevalent patients on January 1, 2010, age 66 & older on December 31, 2009. MarketScan & Ingenix i3: point prevalent patients on January 1, 2010, age 50–64 on December 31, 2009. Adjusted for gender/prior hospitalization/comorbidity; ref: Medicare patients age 66 & older, 2010.

Figure 3.6 Adjusted rates of hospitalization for infection, by dataset & CKD diagnosis code, 2010

Compared to those of patients in the early stages of CKD, rates of admission for infection among patients with CKD of Stages 4–5 are 72, 66, and 50 percent greater, respectively, among Medicare, MarketScan, and Ingenix i3 patients. Medicare: point prevalent patients on January 1, 2010, age 66 &older on December 31, 2009. MarketScan &Ingenix i3: point prevalent patients on January 1, 2010, age 50–64 on December 31, 2009. Adjusted for gender/prior hospitalization/comorbidity; ref: Medicare patients age 66 & older, 2010.

Figure 3.7 Adjusted rates of hospitalization for other causes, by dataset & CKD diagnosis code, 2010

Adjusted all-cause hospitalization rates for other causes, are higher among Medicare patients age 66 and older than in the younger MarketScan and Ingenix i3 populations. Rates are also greatest for patients with CKD compared to those without, and are generally higher in the later stages of the disease.

Medicare: point prevalent patients on January 1, 2010, age 66 & older on December 31, 2009. MarketScan & Ingenix i3: point prevalent patients on January 1, 2010, age 50–64 on December 31, 2009. Adjusted for gender/prior hospitalization/comorbidity; ref: Medicare patients age 66 & older, 2010.

Rehospitalization

Figure 3.8 Adjusted all-cause rehospitalization or death 30 days after live hospital discharge in CKD patients

Adjusted all-cause rehospitalization rates in Medicare CKD patients have slowly decreased during the last decade, from 27 percent in 2002 to 24 percent in 2010. Point prevalent Medicare CKD patients on January 1 of each year, age 66 &older on December 31 of the prior year. Adjusted for age/gender/race; ref: discharges in 2005. Includes discharges from January 1 to December 1 of each year.

Figure 3.9 All-cause rehospitalization or death within 30 days after discharge from all-cause index hospitalization, by CKD stage, 2010

The thirty-day all-cause rehospitalization rate among patients with CKD of Stages 4–5 was 26 percent in 2010, compared to 23 percent in those with Stage 1–2 CKD; rates for death or rehospitalization were 33 and 28 percent, respectively. The rehospitalization rate among CKD patients (24 percent) exceeded the rate of the combined end-point of death or rehospitalization in non-CKD patients, at 22 percent. January 1, 2010 point prevalent Medicare patients, age 66 & older on December 31, 2009; unadjusted. Includes live hospital discharges from January 1 to December 1, 2010

Figure 3.10 All-cause rehospitalization or death within 30 days after discharge from cardiovascular index hospitalization, by CKD stage, 2010

Following discharge from a cardiovascular hospitalizations, rehospitalization rates in 2010 were 18 and 25 percent, respectively, for non-CKD and CKD patients; rates for rehospitalization or death were 21 and 30 percent. January 1, 2010 point prevalent Medicare patients, age 66 &older on December 31, 2009; unadjusted. Includes live hospital discharges from January 1 to December 1, 2010

Table 3.b Percent live hospital discharges in CKD patients with an all-cause rehospitalization within 30 days, 2010

Rates of rehospitalization increase with the severity of CKD, and are highest among males and blacks/African Americans within all groups except patients with CKD of Stages 4–5; rates in these patients are similar by gender and highest in races other than white or black/African American January 1, 2010 point prevalent Medicare patients, age 66 &older on December 31, 2009; unadjusted. Includes live hospital discharges from January 1 to December 1, 2010

Figure 3.11 All-cause rehospitalization or death 30 days after live hospital discharge in Medicare patients, by age & CKD diagnosis code, 2010

Here we highlight the issue of competing risks of mortality and rehospitalization. Rates of rehospitalization rates tend to be lower for older patients, as death precludes the opportunity for readmission. Figure 3.11 demonstrates a pattern of increasing mortality and decreasing rehospitalization rates in older patients with CKD overall and by CKD stage. January 1, 2010 point prevalent Medicare patients, age 66 &older on December 31, 2009; unadjusted.

Figure 3.12 All-cause rehospitalization or death 30 days after live hospital discharge in Medicare patients, by race & CKD diagnosis code, 2010

Rates by race show lower rehospitalization rates among whites compared to blacks/African Americans patients of other races within all stages of CKD. Mortality, however, is also higher in whites, indicating a need for caution when interpreting trends in rehospitalization by race. January 1, 2010 point prevalent Medicare patients, age 66 & older on December 31, 2009; unadjusted.

Figure 3.13 All-cause rehospitalization or death 30 days after live hospital discharge during the transition to ESRD, by cause-specific index hospitalization, 2010

The highest rehospitalization rates during the transition to ESRD are observed following an index hospitalization for infection, with 44 percent of discharges followed by a rehospitalization within 30 days during the first quarter before ESRD initiation. In the quarter following ESRD initiation, 44 percent of discharges from hospitalizations for infection are followed by death or rehospitalization within 30 days. Incident ESRD patients, January 1 to October 1, 2010; age 67 or older, unadjusted.

Mortality rates

Figure 3.14 All-cause mortality rates in Medicare CKD & non-CKD patients

The unadjusted mortality rate in Medicare CKD patients age 66 and older has decreased 40.3 percent since 1995, to 146.2 deaths per 1,000 patient years in 2010. When adjusted for patient characteristics and complexity, however, the rate is lowered considerably, reaching 79.5 in 2010. January 1 point prevalent Medicare patients age 66 &older. Adjusted for age/gender/race/prior hospitalization/comorbidities. Ref: 2005 patients.

Figure 3.15 All-cause mortality rates in Medicare CKD & non-CKD patients, by CKD diagnosis code, 2010

Among non-CKD patients age 66 and older, adjusted mortality rates are 15 percent higher than unadjusted rates. For CKD patients, in contrast, rates adjusted for patient characteristics, hospitalizations, and comorbidities are 41–50 percent lower. Adjusted mortality reaches 115 deaths per 1,000 patient years for patients with Stage 4–5 CKD. January 1, 2010 point prevalent patients age 66 &older. Adjusted for age/gender/race/prior hospitalization/comorbidities. Ref: 2010 patients.

Table 3.c Adjusted mortality rates (per 1,000 patient years at risk) in Medicare patients, by CKD diagnosis code, 2010

Adjusted mortality per 1,000 patient years among Medicare CKD patients age 66 and older is lowest for those with CKD of Stages 1–2, at 20.7; the rate rises to 115 in those with Stage 4–5 CKD. Mortality is consistently higher for men than women, and in patients with Stage 4–5 CKD is 32 percent higher for whites compared to black/African American patients. January 1, 2010 point prevalent patients age 66 &older. Adjusted for age/gender/race/prior hospitalization/comorbidities. Ref: 2010 patients.

Figure 3.16 Adjusted mortality rates in Medicare patients, by comorbidity & CKD diagnosis code, 2010

Adjusted rates of mortality generally increase with patient complexity. Among Stage 4–5 CKD patients without diabetes or cardiovascular disease, for example, the rate is 76 per 1,000 patient years at risk; among those with both diagnoses, it rises to 176. January 1, 2010 point prevalent patients age 66 &older. Adjusted for age/gender/race/prior hospitalization/comorbidities. Ref: 2010 patients.

Figure 3.17 Adjusted mortality rates in Medicare patients, by race & CKD diagnosis code, 2010

By race, adjusted mortality is highest in patients with Stage 4–5, and is highest in whites than in blacks/African Americans. Overall, the rate among blacks/African Americans with CKD is 71 per 1,000 patient years, compared to 78 and 70 among whites and patients of other races. January 1, 2010 point prevalent patients age 66 &older. Adj: age/gender/race/prior hospitalization/comorbidities. Ref: 2010 patients.