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Trends Over Time

Have Admission Rates for Preventable Hospitalizations Changed Over Time?

Between 1994 and 2000, rates of hospital admission improved for particular health conditions. Some of the most striking improvements were:

  • Hospital admission rates for treatment of angina without a procedure dropped 71 percent during the 6-year period.
  • Admission rates for uncontrolled diabetes without complications declined nearly 30 percent.
  • Rates of hospitalization for adult asthma and pediatric gastroenteritis decreased 20 percent.

These reductions may be attributed to a number of factors, including increased patient education, enhanced awareness and access to health care hotlines, better environmental settings, and changes in medical technologies. In addition, lower admission rates may indicate that the quality of primary and preventive care improved for these conditions during this time period.

At the same time, opportunities for improvement exist. Special attention should be directed to conditions for which admission rates increased over time. For example, between 1994 and 2000, rates of hospitalization increased as follows:

  • Chronic obstructive pulmonary disease rose by 20 percent.
  • Hypertension increased by 13 percent.
  • Bacterial pneumonia rose by 9 percent.

Older Americans are at highest risk of hospitalization for these three conditions. More needs to be learned about the reasons for the observed increases so that decisionmakers can work toward eliminating unnecessary hospitalizations.

There are some health conditions for which hospitalization rates did not vary substantially over time. Although it is encouraging that the rates did not rise, the goal is to reduce the need for hospitalization for all conditions that can be effectively managed outside the hospital. Therefore, efforts should be applied to prevent unnecessary admissions for the following conditions: long-term diabetes complications, diabetes-related lower extremity amputations, congestive heart failure, dehydration, urinary tract infection, and low-weight births.

Table 3. Time Trends in Admission Rates for Preventable Conditions

Prevention Quality Indicatora Admission Rate Trend Between
1994 and 2000
Decreaseb No Change Increaseb
Uncontrolled diabetes without complications X    
Short-term diabetes complications     X
Long-term diabetes complications   X  
Diabetes-related lower extremity amputations   X  
Congestive heart failure   X  
Hypertension     X
Angina without a procedure X    
Adult asthma X    
Pediatric asthma   X  
Chronic obstructive pulmonary disease     X
Pediatric gastroenteritis X    
Bacterial pneumonia     X
Dehydration   X  
Urinary tract infection   X  
Perforated appendix X    
Low-weight births   X  

a Full definitions for each Prevention Quality Indicator are in the Glossary section of this report.
b Significant decreases and increases are defined at p<0.05.

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Variations Across U.S. Regions

Do Preventable Hospitalization Rates Vary Across the U.S.?

How Do I Read These Graphs?

These graphs compare the preventable hospitalization rates of three regions (the South,West, and Midwest) to the rates of one common region, the Northeast. To create the graphs, each PQI admission rate for the South,West, and Midwest is divided by the PQI admission rate in the Northeast. As noted, the Northeast admission rate compared to itself equals 1.00. Regions with rates higher than those in the Northeast have bars that cross the reference point, 1.00, while regions with lower rates have bars that do not reach the 1.00 line.

The graphs also display the magnitude of the difference in hospitalization rates between each region relative to the Northeast. For example, compared with the Northeast, admission rates for uncontrolled diabetes without complications are 18 percent higher in the South and 48 percent lower in the West ([1.18-1.00]x100=18%; [1.00-0.52]x100=48%). All rates are adjusted by age and sex, using year 2000 as the standard population.

Variations in hospitalization rates exist across the four U.S. Census regions: Northeast, South,West, and Midwest. The greatest amount of variation occurs for three chronic conditions—uncontrolled diabetes without complications, hypertension, and chronic obstructive pulmonary disease.

Admissions for preventable hospitalizations are most encouraging in the West, where rates are the lowest in the nation for 15 of the 16 PQIs. Conversely, the South has the highest rates of hospitalization for most indicators, including:

  • Uncontrolled diabetes without complications.
  • Short-term diabetes complications.
  • Congestive heart failure.
  • Hypertension.
  • Chronic obstructive pulmonary disease.
  • Four acute conditions: bacterial pneumonia, dehydration, urinary tract infections, and pediatric gastroenteritis.
  • Low-weight births.

For these conditions, the differences in admission rates between the South and the Northeast (the common reference group used in the graph) range from 10 percent for congestive heart failure and low-weight births to 36 percent for urinary tract infections.

The low rates of admission observed in some areas of the country indicate the potential for improvement for other regions, and more research is needed to identify how the health care system can effectively reduce unnecessary hospitalizations.

Select for Figure 1 (Chronic Conditions) and Figure 2 (Acute Conditions and Birth Outcomes).

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Differences Among Priority Populationsiii

Are Particular Age Groups More Likely to be Admitted for Preventable Hospitalizations?

Populations most vulnerable to illness, such as older Americans and very young children, experience the highest rates of admission. Older Americans are more likely than any other age group to be hospitalized, particularly for:

  • Congestive heart failure.
  • Chronic obstructive pulmonary disease.
  • Bacterial pneumonia.

Many hospitalizations among this population may be appropriate because older Americans tend to be more frail and suffer from more illnesses than younger Americans. On the other hand, some admissions may be preventable through better management of chronic conditions throughout the course of the disease and more effective treatment upon onset of acute conditions.

The PQIs for congestive heart failure and chronic obstructive pulmonary disease are particularly relevant to older Americans, as this population is at substantially higher risk of hospitalization for these conditions. As a result, it may be appropriate to apply these prevention quality indicators specifically to individuals 65 years of age and older.

Certain pediatric groups are also more likely to be admitted to U.S. hospitals. In fact, very young children under the age of 5 years have dramatically higher rates of hospitalization than older children. The differences between pediatric groups are most striking in relation to the treatment of:

  • Pediatric gastroenteritis.
  • Bacterial pneumonia.
  • Dehydration.

For these 3 conditions, admission rates for children 0-4 years of age are up to 13 times higher than the admission rates for older children.

In addition, children 0-4 years of age are much more likely than their older counterparts to be hospitalized for asthma, the most common chronic disease among children. Clinicians may be more cautious when treating this age group, which could result in a lower threshold for hospitalization. While such preferences may be appropriate given the increased vulnerability of this patient population, many admissions may be preventable. More work needs to be done to ensure that very young children obtain high quality primary and preventive care and are hospitalized only when necessary.

The underlying causes of disease and reasons for hospitalization likely vary between age groups. For example, gastroenteritis and dehydration among children may be related to environmental and living conditions, whereas these same conditions among older populations may be attributed to other factors. Therefore, it is important to consider such differences when examining the prevention quality indicators across age groups.

Table 4. Admission Rates for Preventable Conditions per 100,000 Population 18 Years and Older, 2000

Prevention Quality Indicatora Age Group
18-44(a) years 45-64 years 65 years
Uncontrolled diabetes without complications 15 36b 59b
Short-term diabetes complications 54 49b 45b
Long-term diabetes complications 33 158b 339b
Diabetes-related lower extremity amputations 5 55b 140b
Congestive heart failure 35 355b 2,321b
Hypertension 15 57b 116b
Angina without a procedure 12 90b 197b
Adult asthma 89 131b 158b
Chronic obstructive pulmonary disease 20 272b 1,138b
Bacterial pneumonia 92 323b 1,815b
Dehydration 32 90b 568b
Urinary tract infection 64 97b 647b
Perforated appendix 230 443b 579b

Table 5. Admission Rates for Preventable Conditions per 100,000 Population Less than 18 Years, 2000

Prevention Quality Indicatora Age Group
0-4(a) years 5-9 years 10-15 years 15-17 years
Pediatric asthma 400 179b 113b 70b
Bacterial pneumonia 465 104b 42b 35b
Dehydration 333 62b 24b 27b
Urinary tract infection 148 39b 20b 51b
Perforated appendix 598 356b 285b 233b
Pediatric gastroenteritis 302 54b 30b 27b

a Full definitions for each Prevention Quality Indicator are in the Glossary section of this report.
b Statistically different from group (a) at p<0.05. Rates are adjusted by age and sex, using year 2000 as the standard population.

Are Preventable Hospitalization Rates Different for Men and Women?

Rates of admission for select conditions vary by patient gender. Women are at increased risk of admission for four conditions:

  • Hypertension.
  • Adult asthma.
  • Dehydration.
  • Urinary tract infections.

The most striking difference occurs for treatment of adult asthma; for this condition, women are more than 2.5 times more likely than men to be admitted to the hospital. This relationship presents a sharp contrast to that observed for pediatric asthma. Among children, girls are approximately 30 percent less likely than boys to be hospitalized for asthma.

On the other hand, women are less likely to be hospitalized for a number of other conditions, including:

  • Long-term diabetes complications.
  • Diabetes-related lower extremity amputations.
  • Congestive heart failure.
  • Angina without a procedure.
  • Bacterial pneumonia.
  • Perforated appendix.

Of these conditions, the gender difference is most dramatic for diabetes-related lower extremity amputations. Hospitalizations involving treatment for this condition are approximately 50 percent lower for women than for men. Again, the causes for this difference are uncertain and more research is needed to better understand why men may be at higher risk for hospital admission.

Select for Figure 3.

Is Community Income Related to Preventable Hospitalization Rates?

The likelihood of hospitalization increases dramatically as median community income decreases. Residents from areas with the lowest median incomes (<$25,000) have the highest rates of admission for every preventable hospitalization indicator. When comparing communities with the lowest incomes to those with the highest incomes, differences in admission rates range from 5 to 74 percent. The greatest amount of variation between the lowest and highest income areas occurs for treatment of:

  • Uncontrolled diabetes without complications.
  • Hypertension.
  • Short-term diabetes complications.
  • Adult asthma.

Community income disparities are less pronounced for treatment of acute conditions than for chronic conditions. For the five acute conditions, admission rates are 6 to 78 percent higher among individuals from the lowest income communities, as compared with residents from areas with median incomes of $45,000 or more.

In contrast, rates of hospitalization vary considerably for treatment of the 10 chronic conditions. Among these conditions, differences in admission rates range from 76 to 278 percent between the lowest and highest income communities. For nine of these conditions, admission rates are at least two times higher among lowest income residents, as compared with residents of the highest income areas.

Select for Figure 4 (Income Disparities in Preventable Hospitalizations for Chronic Conditions) and Figure 5 (Acute Conditions and Birth Outcomes).

Do Admission Rates for Preventable Conditions Differ Between Urban and Rural Residents?

Hospitalization rates for certain conditions vary by location of patient residence; when differences occur, rural residents are consistently at higher risk for being admitted to the hospital.

Hospitalization rates are comparable between urban and rural residents for 6 of the 10 chronic conditions. However, rural residents are more likely to be admitted to the hospital for:

  • Uncontrolled diabetes without complications.
  • Hypertension.
  • Angina without a procedure.
  • Chronic obstructive pulmonary disease.

More room for improvement exists among the acute conditions. Rural residents have higher rates of admission for almost every acute condition, including:

  • Bacterial pneumonia.
  • Dehydration.
  • Urinary tract infections.
  • Pediatric gastroenteritis.

The sole exception among acute conditions is perforated appendix, where the likelihood of admission is similar for urban and rural dwellers. For details, select Figure 6.

Rural residents may consistently have higher rates of hospitalization for acute conditions because of difficulty in accessing care. For example, compared with urban residents, rural residents may have fewer alternatives to hospital treatment. It is also possible that individual care-seeking behaviors and admission thresholds may differ between urban and rural populations. In addition, environmental factors that increase an individual's susceptibility to particular conditions may vary between urban and rural areas.

In recent years, decisionmakers and researchers have placed increased attention on the health and availability of high quality care for rural Americans. As more information becomes available, health care leaders may be able to identify and address the potential disparities experienced by this population.

iii The Healthcare Research and Quality Act of 1999, the re-authorizing legislation for AHRQ, identifies priority populations to be included in research, evaluations, and demonstration projects (Healthcare Research and Quality Act of 1999, Public Law 106-129, § 901, 113 Stat. 1654).

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