2011 USRDS Annual Data Report
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Figure List
Figure 3.1 Change in adjusted all-cause & cause- specific hospitalization rates, by modality
Figure 3.2 Adjusted hospital admission rates & days, by modality
Figure 3.3 Adjusted hospitalization rates, by principal diagnosis & modality
Figure 3.4 Cause-specific rehospitalization rates in the 30 days following live hospital discharge, by age, 2009
Figure 3.5 Cause-specific rehospitalization rates in the 30 days following live hospital discharge, by race/ethnicity, 2009
Figure 3.6 Unadjusted rates of hospitalization for infection, by major organ system & modality
Figure 3.7 Adj. 1st-year hosp adm rates & days (from day 90) in matched HD & PD dialysis pts
Figure 3.8 Unadjusted rates of hospitalization in 20062007 matched incident hemodialysis & peritoneal dialysis patients: all patients
Figure 3.9 Unadjusted rates of hospitalization in 20062007 matched incident hemodialysis & peritoneal dialysis patients: whites
Figure 3.10 Unadjusted rates of hospitalization in 20062007 matched incident hemodialysis & peritoneal dialysis patients: African Americans
Table 3A Unadjusted & adjusted all-cause & cause-specific hospitalization rates (per patient year) in hemodialysis patients
Table 3B Adjusted rates of rehospitalization & rates of death or rehospitalization, by principal diagnosis of index hospitalization
Table 3C Unadjusted & adjusted rates of hospitalization for infection in hemodialysis patients, by major organ system (per 1,000 patient years)
Table 3D Unadjusted all-cause & cause-specific first-year (from day 90) hospitalization rates in matched incident hemodialysis & peritoneal dialysis patients

Chapter Three

Hospitalization

Sections this chapter: 

Introduction

The Annual Data Report has increasingly focused on cause-specific hospitalization as an important surveillance issue. This year we introduce data on infectious complications across organ systems, trying to determine areas of greatest risk to patients. There is a pressing need to address these complications in the hemodialysis population, with the rate of admissions for infection now 43 percent greater than in 1993. The rate for vascular access procedures has, in contrast, fallen 48 percent. Hospitals have made significant progress in using less costly settings to address vascular access interventions, but equivalent progress in lowering the rate of infectious complications is lacking. The use of dialysis catheters continues to have the largest associated risk, a finding well known in the dialysis community.

In the peritoneal dialysis population there has been little change in the overall rate of hospitalization for infection. Admissions for peritonitis, in contrast, have fallen, and in 2009 the rate was close to that for vascular access infections in the hemodialysis population. This latter rate has shown an encouraging decline since 2005, but caution is needed in interpreting this trend, given the increasing rates of hospitalization for bacteremia/sepsis in both the hemodialysis and peritoneal dialysis populations. It is not clear if this increase is related to use of dialysis catheters, even among peritoneal dialysis patients, as a hemodialysis catheter is used as a temporary access until peritoneal dialysis is resumed. Since temporary use of hemodialysis in peritoneal dialysis patients does not change their modality status unless hemodialysis is used for longer than 60 days, detailed assessments of this temporary use of hemodialysis catheters are needed to help define the source of the increased hospitalization rates.

These data look at hospitalization as a single, isolated event. Next we examine data on rehospitalization, overall and by major organ systems, within 30 days of a hospital discharge. Particularly striking is the 36 percent all-cause rehospitalization rate among hemodialysis patients, and the fact that the highest rates occur among patients age 2044. Among patients with an index hospitalization for cardiovascular disease, almost half of the rehospitalizations are related to that primary indication. Interestingly, rates of rehospitalization have changed little over the past decade. It is not clear exactly what type of care is delivered at the index hospitalization to treat the noted condition, and what additional therapy might be given after the initial discharge. Given that fluid overload, congestive heart failure, and vascular access complications are major complications for hemodialysis patients, these findings provide important information on areas for improvement.

We next highlight organ-specific rates of hospitalization for infection. Among hemodialysis patients, rates of hospitalization for both skin and lung infections have been rising since 1993. In the peritoneal dialysis and transplant populations, in contrast, hospitalizations for lung infections have been falling since the early part of the decade, and, interestingly, are similar for both cohorts each comprised of healthier patients, but with very different modalities for kidney replacement treatment. Musculoskeletal infections, including osteomyelitis and joint infections, peaked among hemodialysis patients in 2005, and are almost twice as common in these patients than in those on peritoneal dialysis or with a transplant. The recent drop in abdominal infections in the peritoneal dialysis population is consistent with the improved connection of the peritoneal dialysis catheter to the solution bags. Overall, infections are a major public health concern for the ESRD population, and increased efforts by all members of the care team are needed to address these complications.

We conclude this chapter by comparing hospitalization rates in the peritoneal dialysis and hemodialysis populations, addressing as well the substantial selection bias between the two treatments. (The method for matching these populations, which uses an array of comorbidity and severity of disease measures, is defined in the analytical methods for Chapter One.) In the traditional comparison, overall hospitalization rates in the first and second years are considerably higher for hemodialysis patients than for those treated with peritoneal dialysis. When hemodialysis patients are matched to those on peritoneal dialysis, however, these differences are attenuated, and the higher rates of hospitalizations due to infection in the first year are reversed by the second year. Overall, however, it still that appears peritoneal dialysis patients have fewer hospitalizations than their matched hemodialysis counterparts.

Figure 3.1 Change in adjusted all-cause & cause-specific hospitalization rates, by modality (see page 382 for analytical methods. Period prevalent ESRD patients. Adj: age/gender/race/primary diagnosis; ref: ESRD patients, 2005.)

Overall Hospitalization Top

Figure 3.2 Adjusted hospital admission rates & days, by modality (see page 382 for analytical methods. Period prevalent ESRD patients. Adj: age/gender/race/primary diagnosis; ref: ESRD patients, 2005.)

In 2009, admissions per patient year for hemodialysis patients were nearly identical to those in 1993, at 1.9. Rates for peritoneal dialysis and transplant patients, in contrast, have fallen 13.6 and 16.2 percent. Hospital days per patient year have fallen to 11.8-11.9 for both hemodialysis and peritoneal dialysis patients, and to 5.7 for those with a transplant.

Figure 3.3 Adjusted hospitalization rates, by principal diagnosis & modality (see page 382 for analytical methods. Period prevalent ESRD patients. Adj: age/gender/race/primary diagnosis; ref: ESRD patients, 2005.)

Adjusted cardiovascular admission rates for hemodialysis patients peaked in 2004, at 603 per 1,000 patient years, and have since fallen 12 percent. In the same period, rates for peritoneal dialysis and transplant patients fell 14 and 19 percent, respectively. Rates remain lowest for patients with a transplant, at 123 in 2009.

Peritoneal dialysis patients have the highest rate of admission for any infection, at 573 per 1,000 patient years in 2009; this rate has remained relatively stable since 2000. The admission rate for peritonitis among these patients has been falling since the mid-1990s, from a peak of 169 in 1995 to 103 in 2009, but rates of admission for a peritoneal catheter infection have declined only 10 percent since 2000. Among hemodialysis patients, admissions for vascular access infection rose steadily until 2005; since then, however, they have fallen 19 percent. Admissions for bacteremia/sepsis remain highest for hemodialysis patients, at 108 per 1,000 patient years in 2009.

Table 3.a Unadjusted & adjusted all-cause & cause-specific hospitalization rates (per patient year) in hemodialysis patients (see page 382 for analytical methods. Period prevalent hemodialysis patients age 20 & older. Adj: age/gender/race/primary diagnosis; rates by one factor adjusted for the remaining three; ref: hemodialysis patients, 2005.)

Adjusted all-cause and cause-specific hospitalization rates per patient year among hemodialysis patients have changed little since 19981999. In 20082009, rates were 1.9 and 0.55 for all-cause and cardiovascular hospitalization, and 0.47 and o.11 for hospitalizations due to infection (overall) and to vascular access infection. Patients who are older, female, African American, or have diabetes as their primary cause of renal failure generally have the highest rates of hospitalization overall and for cause-specific conditions. Admissions for vascular access infection, however, are highest among the youngest patients.

Rehospitalization Top

Figure 3.4 Cause-specific rehospitalization rates in the 30 days following live hospital discharge, by age, 2009 (see page 382 for analytical methods. Period prevalent hemodialysis patients age 20 & older, 2009; unadjusted. Includes live hospital discharges from January 1 to December 31, 2009.)

Figure 3.5 Cause-specific rehospitalization rates in the 30 days following live hospital discharge, by race/ethnicity, 2009 (see page 382 for analytical methods. Period prevalent hemodialysis patients age 20 & older, 2009; unadjusted. Includes live hospital discharges from January 1 to December 31, 2009.)

The percentage of patients rehospitalized and alive following an all-cause index hospitalization was 33 overall in 2009, and highest in patients age 20-44, at 41.5 percent. For hospitalizations due to cardiovascular disease, infection, or vascular access, the percentages rehospitalized and discharged alive were again highest in the younger cohort, at 45, 35, and 33, respectively. By race, the percentage of patients rehospitalized and alive was consistently highest in African Americans.

Table 3.b Adjusted rates of rehospitalization & rates of death or rehospitalization, by principal diagnosis of index hospitalization (see page 383 for analytical methods. Period prevalent hemodialysis patients age 20 & older. Adj: age/gender/primary diagnosis; rates by one factor are adjusted for the remaining three. Ref: discharges in 2005. Includes live hospital discharges from January 1 to December 31 of the year. Values show percent live discharges with an all-cause rehospitalization or rehospitalization/death within 14 or 30 days.)

Within 30 days of live discharge, rates of all-cause and cause-specific rehospitalization or rehospitalization or death are noticeably higher than rehospitalization rates within 14 days. For all-cause hospitalizations, the 30-day rehospitalization rate was 36 percent in 20082009, compared to the 14-day rate of 22 percent; rates for rehospitalization or death were 39 and 25 percent, respectively. Cause-specific rates show that 38 percent of patients discharged alive from a cardiovascular hospitalization were rehospitalized within 30 days, compared to 24 percent in 14 days; rates for rehospitalization or death were 41 and 26 percent.

Rehospitalization rates tend to be highest in patients age 2044, are similar by gender, are lowest for patients of races other than white or African American, and are generally higher in African Americans. Few differences are evident by primary diagnosis, and rates after discharge from a cardiovascular hospitalization are higher than those after discharge from a hospitalization for vascular access infection. Among hemodialysis patients with an index hospitalization for cardiovascular disease, almost half of the rehospitalizations are related to that primary indication.

Hospitalization due to Infection, by Major Organ System Top

Figure 3.6 Unadjusted rates of hospitalization for infection, by major organ system & modality (see page 383 for analytical methods. Period prevalent ESRD patients; unadjusted.)

Rates of hospital admission by major organ system vary across modalities. Admissions for circulatory system infections, for example, reached 111 per 1,000 patient years among hemodialysis patients in 2009, compared to 66 and 39 for peritoneal dialysis and transplant patients, respectively. Admissions for abdominal infections, not surprisingly, are highest in peritoneal dialysis patients, at 128 in 2009; this rate has, however, fallen 29 percent since its peak in 1995.

Table 3.c Unadjusted & adjusted rates of hospitalization for infection in hemodialysis patients, by major organ system (per 1,000 patient years) (see page 383 for analytical methods. Period prevalent hemodialysis patients age 20 & older. Adj: age/gender/race/primary diagnosis; rates by one factor adjusted for the remaining three; ref: hemodialysis patients, 2005.)

Unadjusted rates of hospitalization for infection in prevalent hemodialysis patients show little change following adjustments by age, gender, race/ethnicity, and primary diagnosis. Adjusted multivariate associations overall and by major organ system generally include older age, female gender, white race, and diabetes.

Hospitalization in Matched Dialysis Populations Top

Figure 3.7 Adj. 1st-year hosp adm rates & days (from day 90) in matched HD & PD dialysis pts (see page 383 for analytical methods. Incident hemodialysis & peritoneal dialysis patients age 20 & older, 2006-2007; unadjusted. First-year rates show admissions from day 90 to one year after initiation; second-year rates include patients alive & uncensored at the end of the first year.)
Figure 3.8 Unadjusted rates of hospitalization in 2006-2007 matched incident hemodialysis & peritoneal dialysis patients: all patients (see page 383 for analytical methods. Incident hemodialysis & peritoneal dialysis patients age 20 & older, 2006-2007; unadjusted. First-year rates show admissions from day 90 to one year after initiation; second-year rates include patients alive & uncensored at the end of the first year.)
Figure 3.9 Unadjusted rates of hospitalization in 2006-2007 matched incident hemodialysis & peritoneal dialysis patients: whites (see page 383 for analytical methods. Incident hemodialysis & peritoneal dialysis patients age 20 & older, 2006-2007; unadjusted. First-year rates show admissions from day 90 to one year after initiation; second-year rates include patients alive & uncensored at the end of the first year.)

In hemodialysis matched to peritoneal dialysis populations, first-year hospitalization rates (from day 90) in 2008 were 26 percent higher for hemodialysis patients than for peritoneal patients, at 1.9 and 1.5, respectively, per patient year. Hospital days per patient year followed suit, and were 30 percent higher in the matched hemodialysis population, at 12.4 compared to 9.5 days in peritoneal dialysis patients. Incident hemodialysis & peritoneal dialysis patients age 20 & older. Adj: age/gender/race/primary diagnosis; ref: 2005 incident hemodialysis & peritoneal dialysis patients. Rates show first-year admissions from day 90 to one year after initiation.

When hemodialysis patients are matched to peritoneal dialysis patients, unadjusted hospital admission rates in the first year after initiation are 25 percent higher in the hemodialysis population, at 1,921 and 1,542 per 1,000 patient years. Rates for cardiovascular disease, infection, and dialysis-related infection are 36, 8, and, 18 percent higher. In the second year following initiation, however, rates of admission for infection and dialysis access infection are 20 and 39 percent lower in hemodialysis patients compared to peritoneal dialysis patients. Similar patterns are evident in white patients.

Figure 3.10 Unadjusted rates of hospitalization in 2006-2007 matched incident hemodialysis & peritoneal dialysis patients: African Americans (see page 383 for analytical methods. Incident hemodialysis & peritoneal dialysis patients age 20 & older, 2006-2007; unadjusted.)

In African American hemodialysis matched to peritoneal dialysis populations, unadjusted hospital admission rates in the first year after initiation are 22 percent higher in hemodialysis patients, at 2,064 and 1,699, respectively, per 1,000 patient years. Rates of admission for a dialysis access infection are 14 percent higher, but those for overall infection, in contrast, are 8 percent lower. In the second year following initiation, overall hospitalization rates are 8 percent higher in the matched hemodialysis population overall, and 33 percent higher for cardiovascular disease; admission rates for infection and for infection related to a dialysis access, however, are 23 and 37 percent lower.

Table 3.d Unadjusted all-cause & cause-specific first-year (from day 90) hospitalization rates in matched incident hemodialysis & peritoneal dialysis patients (see page 383 for analytical methods. Incident hemodialysis & peritoneal dialysis patients age 20 & older; unadjusted. Rates show first-year admissions from day 90 to one year after initiation. )

In matched dialysis populations, unadjusted all-cause hospitalization rates per 1,000 patient years in 20072008, are, on average 33 percent higher in hemodialysis patients compared to peritoneal dialysis patients across categories of age, gender, race, ethnicity, and primary diagnosis. Similar patterns are evident for cause-specific admissions as well, where admission rates for cardiovascular events, infection, and access-related infection are 50, 17, and 14 percent higher in matched hemodialysis patients compared to rates in those on peritoneal dialysis.