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Overview of Hospitals

Overview of Hospitals in the United States

The following tables and charts provide an overview of the types of U.S. hospitals in 1997 and 2002, as defined by the American Hospital Association (AHA).3 This Fact Book presents information specifically pertaining to U.S. community hospitals. The AHA defines community hospitals as "all non-Federal, short-term (or acute care) general and specialty hospitals whose facilities and services are available to the public."3 Children's hospitals and academic medical centers are also considered to be community hospitals.

Additionally, national estimates of general characteristics for community hospitals in the NIS for 1997 and 2002 follow.

Table 1. AHA Hospital Categories

AHA Hospital Categories 1997 2002
Total number of all U.S. registered hospitals 6,097 5,794
Number of U.S. community hospitals 5,057 4,927
Number of nongovernment hospitals 3,000 3,025
Number of investor-owned (for-profit) community hospitals 797 766
Number of State and local government community hospitals 1,260 1,136

Select for Figure 1 (5 KB), Types of U.S. Hospitals, 2002.

Table 2. Characteristics of U.S. Community Hospitals

Characteristics of U.S. Community Hospitals 1997 2002
Total discharges 34,680,000 37,804,000
Discharges per 100,000 population1,4 12,720 13,128
Total (aggregate) chargesiv $492 billion $650 billion
Mean charges per stay $13,900 $17,300
Percent of discharges from:
  Metropolitan hospitals 84.1 84.6
  Teaching hospitals 46.6 45.3
  Non-Federal government hospitals 13.8 13.6
  Private not-for-profit hospitals 74.6 74.3
  Private for-profit hospitals 11.5 12.1

iv Information presented for 1997 charges has been adjusted for inflation and noted in 2002 dollars.

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Gender and Age Characteristics

Who Is Admitted to the Hospital?

Gender Characteristics of Hospitalizations

  • Nearly 60 percent of all hospitalizations are for women—just as in 1997.
  • Among hospitalized patients 0-17 and 45-64, there are nearly equal numbers of males and females. However, for patients 18-44, 3 out of 4 hospitalized patients are women, many of whom are hospitalized for pregnancy-related conditions.

Select for Figure 2 (4 KB), Gender of Patients in the Hospital (All Ages).

Age Characteristics of Hospitalizations

  • The mean age for hospitalized patients is about 48 years, which is similar to 1997, when the mean age was 47 years.
  • People age 65 and older continue to account for more hospital stays than any other age group. This group is followed closely by individuals ages 18-44.
  • While people 65 and older comprise about 12 percent4 of the U.S. population, they account for about 35 percent of all hospital stays. In contrast, people 18-44 comprise roughly 40 percent of the U.S. population but account for only 27 percent of all hospital stays.

Select for Figure 3 (11 KB), Percent of Hospital Stays by Age Group.

Select for Figure 4 (11 KB), Percent of Population vs. Percent of Hospital Stays.

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Common Diagnoses

Why Are Patients Admitted to the Hospital?

Most Frequent Reasons for Hospitalizationsv

  • The most common reason for hospitalization continues to be infant birth (newborns), which accounts for 11 percent of all hospital discharges.
  • Cardiovascular diseases continue to be a common reason for hospitalization. Five of the top 10 conditions for hospitalization relate to cardiovascular disease: coronary atherosclerosis (hardening of the heart arteries and other heart disease), congestive heart failure, chest pain, heart attack, and irregular heart beat.
  • Chest pain—a nonspecific diagnosis—replaced stroke as 1 of the top 10 reasons for hospitalization. From 1997 to 2002, admission from stroke decreased by 12 percent (638,431 admissions to 564,129 admissions). Hospitalizations resulting from stroke have fallen from the 7th most frequent reason for admission to the 15th.
  • Similar to 1997, one of the most frequent reasons for hospitalization in 2002 is a mental health diagnosis—affective disorders (primarily depression). Affective disorders continue to account for nearly 2 percent of all discharges from the hospital.

Table 3. Top 10 Principal Diagnoses in U.S. Hospitals

Top 10 Principal Diagnoses in U.S. Hospitals Total Number of Discharges
(in thousands)
Percent of All Discharges
1. Newborn infant 4,155 11.0
2. Hardening of the heart arteries (coronary atherosclerosis) 1,293 3.4
3. Pneumonia 1,275 3.4
4. Congestive heart failure 1,058 2.8
5. Chest pain 885 2.3
6. Trauma to vulva (external female genitals) and perineum (area between anus and vagina) due to childbirth 804 2.1
7. Heart attack (acute myocardial infarction) 764 2.0
8. Cardiac dysrhythmias (irregular heart beat) 713 1.9
9. Other maternal complications of birth and puerperium (period after childbirth) 694 1.8
10. Affective or mood disorders (depression and bipolar disorder) 655 1.7

Most Common Reasons for Hospitalization by Age Groups

  • Pneumonia is the only diagnosis in the top 10 conditions for each age group.
  • For patients 18-44, 9 of the top 10 reasons for hospitalization pertain to pregnancy and delivery. When pregnancy and childbirth are excluded, 3 of the top 10 conditions relate to mental illness or substance abuse. Alcohol-related conditions dropped from the 4th most common condition in 1997 to the 11th in 2002, representing a drop of 18 percent.
  • Depression is 1 of the top 10 conditions for patients in 3 different age groups: 1-17, 18-44, and 45-64.
  • For all age groups 45 and older, hardening of the arteries, heart attack, and congestive heart failure are among the top 10 reasons for hospitalization.
  • Some conditions are in the top 10 only within particular age groups:
    • Hip fracture—patients 80 and older.
    • Cardiac dysrhythmia—patients 65 and older.
    • Urinary tract infection—patients less than 1 year of age, as well as patients 80 and older.
    • Asthma—patients 1-17.

Select for Table 4, Top 10 Principal Diagnoses by Age Group.

Most Common Reasons for Hospital Stays by Body System

Major Diagnostic Categories (MDCs) are used to define "body systems." MDCs are broad categories of Diagnosis Related Groups (DRGs) that relate to an organ or a system (the digestive system, for example).

  • Diseases of the circulatory system remain the most frequent reason for hospitalization, accounting for 17 percent of all hospital stays. These include conditions such as coronary atherosclerosis (hardening of the heart arteries), congestive heart failure, heart attack, and irregular heart beat.
  • The next most common reasons for hospitalization by body system continue to be pregnancy and childbirth (diagnoses received by women), followed by newborns and other perinatal conditions (diagnoses received by babies).
  • Hospitalizations for all mental disorders combined account for approximately 4 percent of all hospital stays in short-term community hospitals and rank as the 8th most common reason for hospitalization by body system, just as in 1997.
  • The top 10 common reasons for hospital stays by body system (based on Major Diagnostic Categories) are nearly identical to those in 1997 with one exception—diseases of the endocrine system now appear in the top 10, replacing diseases of the female reproductive system. This change is attributable to a single Diagnosis Related Group, obesity-related operating room (OR) procedures, which increased by more than 370 percent (from 16,429 discharges in 1997 to 77,335 discharges in 2002).

Table 5. Top 10 Reasons for Hospital Stay, by Body System

Top 10 Reasons for Hospital Stay, by Body System Total Number of Discharges
(in thousands)
Percent of All Discharges
1. Diseases of the circulatory system 6,462 17.1
2. Pregnancy and childbirth 4,639 12.3
3. Newborns and perinatal conditions 4,279 11.3
4. Diseases of the respiratory system 3,659 9.7
5. Diseases of the digestive system 3,253 8.6
6. Diseases of the musculoskeletal system 2,916 7.7
7. Diseases of the nervous system 2,077 5.5
8. Mental disorders 1,314 3.5
9. Diseases of the kidney and urinary tract 1,248 3.3
10. Diseases of the endocrine system 1,229 3.3

Comorbidities

Comorbidities are defined as coexisting medical problems listed as secondary diagnoses on a patient's hospital record; they are not the principal diagnosis or the main reason for admission, and they are distinguished from complications that arise during the hospital stay.5

Comorbidities can make a hospital stay more expensive and complicated. Conditions are designated as comorbidities if they are not directly related to the principal diagnosis and are likely to have originated prior to the hospital stay.

  • Nearly 60 percent of hospitalized patients have at least one comorbidity—an increase from 54 percent in 1997. Thirty-seven percent of hospital stays had two or more comorbidities, compared with 33 percent of hospital stays in 1997—a 12-percent increase.

Select for Figure 5 (5 KB), Comorbidities Among Hospitalized Patients.

Most Common Comorbidities

  • Hypertension is the most common comorbidity. About 30 percent of patients with comorbidities have hypertension in addition to their principal diagnosis—up from 20 percent in 1997. It is not clear to what extent this increase is due to more careful coding of underlying conditions, better detection of disease, or increased prevalence.
  • Depression and obesity are among the 10 most frequent comorbidities, appearing as secondary diagnoses for about 5 percent and 4 percent of all hospital stays, respectively. These conditions were not among the top 10 comorbidities in 1997.
  • The 4th most common comorbidity—fluid and electrolyte disorders—is associated with many conditions and may be a marker for the severity of the principal diagnosis or may actually be a condition that arises in the hospital.

Table 6. Top 10 Comorbidities for Hospital Stays

Top 10 Comorbidities for Hospital Stays Total Number of Cases With Each Comorbidity
(in thousands)
Percent of All Discharges
1. Hypertension (high blood pressure) 11,104 29.4
2. Chronic obstructive lung disease 4,579 12.1
3. Diabetes mellitus 4,446 11.8
4. Fluid and electrolyte disorders (primarily dehydration and fluid overload) 4,404 11.7
5. Iron deficiency and other anemia 2,997 7.9
6. Congestive heart failure 2,162 5.7
7. Hypothyroidism 2,120 5.6
8. Affective or mood disorders (depression and bipolar disorder) 1,757 4.7
9. Other neurological disorders 1,583 4.2
10. Obesity 1,346 3.6

Variations in Comorbidities by Age Group

  • The most common comorbidity for patients under 18 is fluid and electrolyte disorders.
  • For adults (18 years and older), hypertension is, by far, the most common comorbidity. For adults younger than 80, the second most common comorbidity is diabetes, while the second most common for those 80 and older is fluid and electrolyte disorders.
  • Depression and obesity are among the top 10 comorbidities for adolescents and adults up to age 64.
  • Alcohol and drug abuse continue to be common comorbidities. Drug abuse is a top 10 comorbidity for children and adolescents 1-17 and for adults 18-44. Alcohol abuse is a top 10 comorbidity for adults in both the 18-44 and 45-64 age groups.

Select for Table 7, Top 10 Comorbidities by Age Group.


v Go to the Appendix for the complete listing of all principal diagnoses.


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Source of Admissions

How Are Patients Admitted to the Hospital?

Admission Status

Admission status refers to how a patient presents to the hospital: routine, from the emergency department, from another hospital, or from a long-term facility. Each of these categories is described below.

Routine admission— Patient was not admitted from the emergency department or any other health care facility. This admission source includes admission from home, via physician or clinic referral, or birth.

Emergency department (ED) admission— Patient was admitted to the hospital through the ED.

Admission from another hospital— Patient was admitted to this hospital from another short-term, acute care hospital. This usually signifies that the patient required the transfer in order to obtain more specialized services that the originating hospital could not provide.

Admission from long-term care facility— Patient was admitted from a long-term facility, such as a nursing home.

The 2002 hospital data indicate:

  • Approximately 50 percent of admissions are routine in nature.
  • About 43 percent of all hospital admissions originate in the ED.
  • The remaining 7 percent of hospital admissions are from another short-term hospital, a long-term hospital, or of unknown origin.

Select for Figure 6 (5 KB), Nature of Admissions.

Admissions Through the Emergency Department

Admissions through the ED tend to more expensive and serious than routine admissions.

  • In 2002, about 43 percent of all hospital admissions originated in the ED. This finding is a nearly 18 percent increase above 1997, when 37 percent of admissions were initiated through the ED.
  • Six of the top 10 conditions for which patients are admitted through the ED continue to be related to the circulatory system: congestive heart failure, chest pain, coronary atherosclerosis (hardening of the heart arteries), heart attack, irregular heart beat, and stroke.
  • Two of the top 10 conditions for ED admissions relate to respiratory problems—pneumonia (6 percent of admissions through the ED) and chronic obstructive lung disease (3 percent). Asthma is no longer among the top 10 conditions admitted through the ED. In 1997, asthma ranked 9th and in 2002, 13th.
  • In 1997, 2 infections, pneumonia and septicemia, were among the 10 most frequent conditions admitted through the ED. However, in 2002, pneumonia remains the only infection in this category. Septicemia dropped from the 10th to the 16th most frequent condition for admission through the ED.
  • Among the 10 most frequent reasons for admission through the ED, 2 new conditions emerged in 2002: fluid and electrolyte disorders and affective disorders. These conditions were ranked 11th and 13th, respectively, in 1997.

Table 8. Top 10 Principal Diagnoses for Hospital Discharges Admitted Through the ED

Top 10 Principal Diagnoses for Hospital Discharges Admitted Through the ED Total Number of Discharges
(in thousands)
Percent of All Hospital Discharges Admitted Through the ED
1. Pneumonia 892 5.5
2. Congestive heart failure 768 4.7
3. Chest pain 722 4.4
4. Hardening of the heart arteries and other heart disease 566 3.5
5. Heart attack (acute myocardial infarction) 500 3.1
6. Acute cerebrovascular disease (stroke) 445 2.7
7. Chronic obstructive lung disease 445 2.7
8. Cardiac dysrhythmias (irregular heart beat) 433 2.7
9. Fluid and electrolyte disorders (primarily dehydration and fluid overload) 393 2.4
10. Affective or mood disorders (depression and bipolar disorder) 336 2.1

Admissions Through the ED by Payer

  • Medicare cases represent 45 percent of all hospitalizations beginning in the ED, followed by private hospitalizations (26 percent), Medicaid hospitalizations (20 percent), and uninsured hospitalizations (7 percent).
  • The percent of hospitalizations that begin in the ED varies by payer type: 61 percent of uninsured hospitalizations, 57 percent of Medicare hospitalizations, 39 percent of Medicaid hospitalizations, and 31 percent of privately insured hospitalizations.

Select for Figure 7 (13 KB), Percent of Hospital Stays Attributed to Each Payer.

Variations in ED Admissions by Age Group and Gender

  • The percentage of people admitted to the hospital through the ED increased for all age groups, with the largest increase seen for elderly patients.
  • For patients 1-17 years of age, a 10-percent increase occurred in the percent of patients admitted through the ED. In 2002, 45 percent of admissions occurred through the ED, compared with 41 percent in 1997.
  • For patients ages 45 and older, the proportion admitted through the ED increased the most. For patients 80+, 55 percent were admitted through the ED in 1997, as compared with 64 percent in 2002—a 19-percent increase.
  • Individuals 18-44 years of age have the lowest percentage of admissions that begin in the ED—35 percent—relative to any other age group.
  • Overall, a greater proportion of hospitalizations for males—48 percent—originate in the ED, as compared with 40 percent for females. In younger age groups, a substantially greater proportion of hospitalizations for males begin in the ED, as compared with females; however, for adults 65 years and above, slightly more hospitalizations for females originate in the ED.

Select for Figure 8 (7 KB), Admissions Initiated Through the ED.

Select for Figure 9 (8 KB), Percent of Hospitalizations Beginning in the ED by Gender.

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