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 Figure 5.1Adjusted hospitalization rates for ESRD patients, by treatment modality, 2005-2014
 Figure 5.2Adjusted all-cause & cause-specific hospitalization rates for ESRD patients, by treatment modality, 2005-2014
 Figure 5.3Map of the Hospitalization rate (admission per person year) of ESRD, by Health Service Area, in the U.S. population, 2014
 Table 5.1Rates of all-cause & cause-specific hospitalization per patient year for adult hemodialysis patients, 2004-2014
 Figure 5.4Adjusted hospital days for ESRD patients, by treatment modality, 2005-2014
 Figure 5.5Adjusted hospital days for infection & cardiovascular causes, for ESRD patients by their treatment modality, 2005-2014
 Figure 5.6Proportion of patients aged 66 & older discharged alive from the hospital who either were rehospitalized or died within 30 days of discharge, by kidney disease status, 2014
 Figure 5.7Proportion of hemodialysis patients discharged alive from the hospital who either were rehospitalized or died within 30 days of discharge, by demographic characteristics, 2014
 Figure 5.8Proportion of hemodialysis patients discharged alive that either were rehospitalized or died within 30 days of discharge, by cause of index hospitalization, 2014
 Figure 5.9Proportion of hemodialysis patients with cause-specific rehospitalizations within 30 days of discharge, by cause of index hospitalization, 2014
 Figure 5.10Proportion of hemodialysis patients discharged alive that either were rehospitalized or died within 30 days of discharge for cardiovascular index hospitalization, by age, 2014
 Figure 5.11Proportion of hemodialysis patients discharged alive that either were rehospitalized or died within 30 days of discharge for cardiovascular index hospitalization, by cause-specific cardiovascular index hospitalization, 2014
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Chapter 5: Hospitalization

Highlights

  • On average, ESRD patients are admitted to the hospital nearly twice a year. About 30% of those have an unplanned rehospitalization within the 30 days following discharge.
  • Hospitalization represents a significant societal and financial burden, accounting for approximately 40% of total Medicare expenditures for dialysis patients.
  • Over the past decade, the frequency of hospital admissions and resulting number of hospital days for ESRD patients have declined gradually, but fairly consistently. In 2014, the adjusted rate of admission for hemodialysis (HD) patients decreased to 1.7 days per patient year (PPY) as compared to 2.1 in 2005, a reduction of 19.0%. During that same period, admission rates for peritoneal dialysis (PD) patients fell by about 23.8%, to 1.6 in 2014 from 2.1 in 2005. For transplant patients this reduced by 27.2% to 0.8 days in 2014, from 1.1 in 2005 (Figure 5.1).
  • During this same decade, hemodialysis patient hospitalizations due to cardiovascular events or for vascular access infection fell by 32.6 % and 71.4% (Table 5.1).
  • In 2013-2014, some patient groups exhibited a higher risk of hospitalization, both overall and for most cause-specific diagnoses. There was inconsistent variation by age. Hospitalization rates were 17% higher for females than for males. Whites were hospitalized more often than those of other races by approximately 33%, and Blacks by approximately 31%. Persons with diabetes were 10% more likely to be hospitalized than the overall patient average (Table 5.1).
  • Patients with CKD and ESRD experienced rehospitalization rates of 21.4% and 34.6%, as compared to only 15.3% of the older Medicare beneficiaries without a diagnosis of kidney disease (Figure 5.6).
  • Among hemodialysis patients prevalent in 2014, 36.6% of discharges from a hospitalization for any cause were followed by a rehospitalization within 30 days (Figure 5.7a).

Introduction

Admissions and readmissions to the hospital represent major burdens for patients with end-stage renal disease (ESRD). On average, ESRD patients are admitted to the hospital nearly twice a year, and about 30% have an unplanned rehospitalization within the 30 days following discharge (CMS, 2014). Given the disruption of everyday life stemming from dialysis treatment, hospital admissions and readmissions additionally compromise patients’ well-being and quality of life and are associated with adverse clinical outcomes. Furthermore, inpatient treatment represents a significant societal and financial burden, accounting for approximately 40% of total Medicare expenditures for dialysis patients (CMS, 2014).

Clinical studies conducted in a broad range of settings have demonstrated that both improved health care and care coordination may reduce rates of unplanned or non-elective hospitalization and rehospitalization; some studies have suggested that a sizable portion of such readmissions may be preventable. Hence, monitoring trends in hospitalization and rehospitalization is a key to ensuring that quality of care is maintained, potential problems are identified, and cost-effective health care is provided. Informed care providers can respond with targeted strategies to prevent or minimize inappropriate admissions and reduce the incidence of rehospitalization.

Methods

The findings presented in this chapter were drawn from multiple data sources, including the Centers for Medicare & Medicaid Services (CMS), the Centers for Disease Control and Prevention (CDC), and the United States Census. Details of these are described in the Data Sources section of the ESRD Analytical Methods chapter.

See the Analytical Methods Used section of the ESRD Analytical Methods chapter for an explanation of the analytical methods used to generate the study cohorts, figures, and tables in this chapter.

Trends in Hospitalization Rates

Over the past decade, the frequency of hospital admissions and resulting number of hospital days for ESRD patients have declined gradually, but fairly consistently. As shown in Figure 5.1, in 2014 the adjusted rate of admission for hemodialysis (HD) patients decreased to 1.7 per patient year (PPY) as compared to 2.1 in 2005, a reduction of 19.0%. During that same period, rates for peritoneal dialysis (PD) patients fell by about 23.8%, from 2.1 in 2005 to 1.6 in 2014; rates for transplant patients reduced by 27.2%, from 1.1 to 0.8.

Figure 5.1 Adjusted hospitalization rates for ESRD patients, by treatment modality, 2005-2014

In recent years, the Annual Data Report (ADR) has highlighted cause-specific hospitalization as an important morbidity surveillance issue. Between 2005 and 2014, rates of hospitalizations due to any cause among ESRD patients declined from 2.07 to 1.64 per patient year (PPY). The 8.7% overall decline in hospitalizations due to infection was more pronounced among patients on PD (23.8%) and those with a transplant (11.5%), as compared to HD patients (10.6%; see Figure 5.2). These improvements likely reflect, at least in part, targeted interventions to prevent and reduce infection rates, especially among PD and transplant patients. Hospital admissions resulting from other causes have also decreased over the same period (e.g., a 61.3% decrease in hospitalizations was observed for vascular access procedures).

Figure 5.2 Adjusted all-cause & cause-specific hospitalization rates for ESRD patients, by treatment modality, 2005-2014

All-cause hospitalization rates among adult HD patients decreased by 18.3% from 2005 to 2014 (see Table 5.1). Hospitalizations due to cardiovascular events and those for vascular access infection fell by 32.6% and 71.4%, respectively. Patient groups with a higher risk of overall hospitalization included those aged 22–44 years or 75 years and older, females, those of White or Black/African American race. Patients who had diabetes as their primary cause of kidney failure had a higher risk of hospitalization both overall and for most cause-specific diagnoses.

While the overall trends of decreasing hospitalization rates are encouraging, it is plausible that these global and cause-specific declines were influenced at least in part by changes in clinical care practices, and policies that emphasize greater utilization of ambulatory care services.

The 2014 unadjusted hospitalization rate of ESRD ranged across 805 U.S. Health Service Areas (HSAs) from a low of 1.57*10-7 PPY to a high of 2.28 PPY (interquartile range: 0.7944 PPY; Figure 5.3a). The rates were generally highest in parts of the Ohio, southern Texas, and Florida and lowest in Alaska and certain Upper Midwest and Rocky Mountain states. The adjusted hospitalization rate of ESRD in 2014 ranged across the HSAs, from a low of 0.60 PPY to a high of 3.25 (interquartile range: 0.4601 PPY; Figure 5.3b). The rates were generally highest in parts of the Northeast, Florida, and Ohio and lowest in certain Upper Midwest and Rocky Mountain states.

Figure 5.3 Map of the Hospitalization rate (admission per person year) of ESRD, by Health Service Area, in the U.S. population, 2014

Table 5.1 Rates of all-cause & cause-specific hospitalization per patient year for adult hemodialysis patients, 2004-2014

Hospital Days

Continuing a downward trend observed since 2005, the number of total hospital days PPY among all dialysis patients has decreased from 14.7 to 10.9 (Figure 5.4). From 2005 to 2014, hospital days PPY decreased to 10.9 for HD patients, 11.1 for PD patients, and to 5.2 days for those with a functioning kidney transplant.

Figure 5.4 Adjusted hospital days for ESRD patients, by treatment modality, 2005-2014

With patient-specific adjustment, the number of infection-related hospital days PPY decreased by 16.3% for HD patients, 30.1% for patients on PD, and 18.0% for patients with a kidney transplant. The number of inpatient days for cardiovascular hospitalization reduced by 42.0% for all dialysis patients, and by 46.8% for those with a transplant.

Even after adjustment, the number of hospital days due to infections and cardiovascular events for patients on dialysis were more than twice that of those with a transplant. For HD and PD patients in 2014, infection-related hospital days were 3.5 and 4.0 PPY, respectively, compared to 1.6 PPY for those with a transplant. Among patients with a cardiovascular admission, hospital days were 2.1 and 2.2 PPY for HD and PD patients, as compared to 0.6 PPY for those with a transplant.

Figure 5.5 Adjusted hospital days for infection & cardiovascular causes, for ESRD patients by their treatment modality, 2005-2014

Rehospitalization

Readmissions following a hospital discharge are an important predictor of subsequent adverse clinical events, both in the general and ESRD populations. Among dialysis patients, rehospitalizations are associated with increased morbidity and mortality, and reduced quality of life. Recurrent hospitalizations also pose a significant societal and financial burden, particularly for ESRD patients.

In this chapter rehospitalization/readmission is defined as a hospital admission occurring within 30 days of a hospital discharge, excluding ER visits and those for rehabilitation purposes. Hospital readmissions with associated death were more common among patients with chronic kidney disease (CKD) or ESRD than in the general population. Patients with CKD and ESRD experienced rehospitalization rates of 21.4% and 34.6%, respectively as compared to only 15.3% of older Medicare beneficiaries without a diagnosis of kidney disease (Figure 5.6). This held true for the combined outcomes of post-discharge death and/or rehospitalization—experienced by 27.6% of CKD patients and 40.1% of those with ESRD, versus only 19.8% of patients without diagnosed kidney disease.

Figure 5.6 Proportion of patients aged 66 & older discharged alive from the hospital who either were rehospitalized or died within 30 days of discharge, by kidney disease status, 2014

Among HD patients prevalent in 2014, 36.6% of discharges from a hospitalization for any cause were followed by a rehospitalization within 30 days (see Figure 5.7a). For older patients, rehospitalization rates decreased as mortality increased, illustrating these competing risks, as death precluded the outcome of readmission. Rates of post-discharge death without rehospitalization, for example, were highest in patients aged 75 years and older, at 7.2%, while these patients had the lowest rehospitalization rates, at 33%.

Figure 5.7 Proportion of hemodialysis patients discharged alive from the hospital who either were rehospitalized or died within 30 days of discharge, by demographic characteristics, 2014

The highest rates of rehospitalization with survival occurred for adults aged 22 to 44 years—42.0% of their discharges were followed by a readmission within 30 days. For the two combined outcomes of either survival or death, the highest rates were again seen among patients aged 20–44 years, at 43.1%. The rate of survival following rehospitalization exceeded the two combined death outcomes for all age groups (33.5% vs. 6.8%), even in patients aged 75 and older, at 28.1% and 12.0%, respectively. These data illustrate that the observed, elevated rehospitalization rates among younger versus older groups were not fully due to the competing risk of mortality in the aged.

We examined the proportion of HD patients discharged alive who were either rehospitalized or died within 30 days of discharge by their race & ethnicity; the highest rates were observed among the aggregate Other race group (36.3% for rehospitalized and lived vs. 38.3% for rehospitalized with the combined outcomes of either survival or death), followed by Blacks (35.1% vs. 37.7%). The lowest such rates occurred among Asians, of whom 29.1% were rehospitalized and lived, and 32.2% were rehospitalized with the combined outcomes of either survival or death. The highest rate of post-discharge death occurred among White HD patients at 3.6%, possibly influenced by the older average age among White HD patients.

For HD patients, the all-cause rehospitalization rate in 2014 was 37.0% (Figure 5.7a). For index hospitalizations due to cardiovascular, infection, and vascular access infections, patients’ rehospitalization rates were 37.7, 34.0, and 30.6%, respectively (see Figure 5.8).

Figure 5.8 Proportion of hemodialysis patients discharged alive that either were rehospitalized or died within 30 days of discharge, by cause of index hospitalization, 2014

Figure 5.9 illustrates that rehospitalization in the 30 days following a hospital discharge does not always result from a similar diagnostic cause as the index hospitalization.

During 2014, of those admitted for treatment of cardiovascular issues and then soon rehospitalized, nearly half (42.5%) were admitted to treat the same or another cardiovascular condition. However, this pattern differed for those initially hospitalized to address vascular access infection (16.7%), and other types of infection (35.6%).The proportion of cause-specific readmission among those with an all-cause index hospitalization were also fairly low—only 23.7% returned for additional cardiovascular treatment, 1.8% for vascular access infection, and 20.3% to address other types of infection.

The patterns of rehospitalization following an unrelated index hospitalization suggest the development of new conditions or complications of the original condition. These differences might in part be attributed to the nature of chronic conditions that typically do not resolve (i.e. cardiovascular disease) versus acute conditions that are expected to resolve (i.e. infection).

Figure 5.9 Proportion of hemodialysis patients with cause-specific rehospitalizations within 30 days of discharge, by cause of index hospitalization, 2014

Rehospitalization rates following discharge from a cardiovascular index hospitalization were slightly higher among younger adults, compared with all other age groups in which rehospitalization rates appear similar. For those aged 22–44, for example, 46.0% of such discharges were followed by a rehospitalization within 30 days (Figure 5.10). In general, these rates mirrored those for all-cause index hospitalizations as seen in Figure 5.6, although the rates in Figure 5.9 for those aged 22-44 were slightly higher.

Figure 5.10 Proportion of hemodialysis patients discharged alive that either were rehospitalized or died within 30 days of discharge for cardiovascular index hospitalization, by age, 2014

For cardiovascular index hospitalizations (Figure 5.11), rehospitalization occurred most frequently following discharge from treatment of acute myocardial infarction (AMI) and stroke, at 40.6 and 38.5%, respectively. The lowest rates occurred following discharge after dysrhythmia, at 33.9%. When not rehospitalized, stroke patients had the highest post-discharge mortality rate at 7.6%.

Figure 5.11 Proportion of hemodialysis patients discharged alive that either were rehospitalized or died within 30 days of discharge for cardiovascular index hospitalization, by cause-specific cardiovascular index hospitalization, 2014

As comorbid cardiovascular disease and its complications have a critical interaction with kidney disease of all types, this 2016 ADR features two chapters specifically addressing these issues—Volume1, Chapter 4 Cardiovascular Disease in Patients with CKD, and Volume 2, Chapter 9, Cardiovascular Disease in Patients with ESRD.

References

Center for Medicare and Medicaid Services (2014, June). Report for the Standardized Readmission Ratio. Retrieved October 23, 2015, from https://www.cms.gov/Medicare/Quality-Initiatives-Patient-Assessment-Instruments/ESRDQIP/Downloads/MeasureMethodologyReportfortheProposedSRRMeasure.pdf