Characteristics of hospital stays, 2012

Table 1 presents utilization and cost data for hospital inpatient stays in 2012 by selected patient and hospital characteristics.

Table 1

Number and rate of hospital stays, length of stay, and costs by patient, payer, community income, and hospital characteristics, 2012.

• In 2012, there were about 36.5 million hospital stays with an average length of stay of 4.5 days and an average cost of $10,400 per stay.
  In 2012, there were approximately 36.5 million hospital stays in the United States, representing a hospitalization rate of 116.2 stays per 1,000 population. Across all types of stays, the average length of a hospital stay was 4.5 days. Aggregate hospital costs were $377.5 billion, and the average cost per stay was $10,400.
• Hospital utilization and costs varied substantially in relationship to patient and hospital characteristics.
  The rate of hospitalization was highest among infants, which included hospital births (newborns), at 1,070.9 stays per 1,000 population. With the exception of infants, the hospitalization rate increased with age from 21.1 stays per 1,000 population among 1–17 year olds to 502.0 stays per 1,000 population among those aged 85 years and older.
  Adults aged 18–44 years had the shortest average length of stay (3.6 days), followed by infants and children up to 17 years of age (3.8 to 3.9 days). Among adults, lengths of stay were longer as patient age increased, with adults aged 65 years and older having the longest average length of stay (5.2 days). Average cost per stay was lowest for infants ($5,000) and highest for adults aged 45–84 years ($12,900 to $13,000).
  Females had a higher rate of hospitalization (132.0 stays per 1,000 population) than males (99.9 stays per 1,000 population). The average length of a hospital stay was shorter for females than for males (4.3 vs. 4.8 days), and the average cost of a hospital stay was lower for females than for males ($9,400 vs. $11,700). It is important to note that maternal stays for females admitted for pregnancy and delivery were included in this analysis. Analyses excluding maternal and neonatal (newborn) stays showed the same relative differences between males and females (data not shown). Excluding maternal and neonatal conditions and compared with males, females had a higher rate of hospitalization (93.9 vs. 86.9 stays per 1,000 population), a shorter average length of stay (4.8 vs. 5.0 days), and lower average cost per stay ($11,400 vs. $12,800).
  Medicare paid for the largest number of hospitalizations (14.3 million stays), followed by private insurance (11.2 million stays) and Medicaid (7.6 million stays). About 2 million hospital stays were for patients without insurance. Patients covered by Medicare experienced the longest average length of stay (5.2 days), and privately insured patients had the shortest average length of stay (3.8 days). Average cost per stay was highest for Medicare hospitalizations ($12,200) and lowest for Medicaid hospital stays ($8,100).
  Communities with low income levels had a higher rate of hospitalization than did communities with higher income levels (136.8 vs. 106.1 stays per 1,000 population). Compared with patients from higher income communities, patients from low income communities had a longer average length of stay (4.6 vs. 4.4 days) and lower average hospital costs ($9,700 vs. $10,600).
  The West had a lower rate of hospitalization (97.2 stays per 1,000 population) compared with the other regions (range: 120.4 to 125.2 stays per 1,000 population). The Northeast had the longest average length of stay at 4.9 days, and the West and Midwest had the shortest average lengths of stay (4.2 and 4.3 days, respectively). The West had the highest average hospital cost ($12,300) and the South had the lowest average hospital cost ($9,300).

Figure 1 provides the distribution of hospital stays by patient age, primary payer, and hospital region, comparing each subgroup by type of stay—surgical, medical, and maternal or neonatal.

Figure 1

Distribution of inpatient stays by patient age group, primary payer, hospital region, and type of stay, 2012. Source: Agency for Healthcare Research and Quality (AHRQ), Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project (more...)

• Medical stays constituted the largest proportion of hospitalizations.
  Overall, medical stays constituted the largest proportion of hospital stays, representing 56.0 percent of all hospitalizations. Maternal/neonatal stays and surgical stays each constituted approximately 22 percent of hospitalizations. More than two-thirds of hospitalizations were medical stays for the second youngest and three oldest age groups: 1–17 years (73.6 percent), 45–64 years (67.3 percent), 65–84 years (70.5 percent), and 85+ years (84.8 percent). Medical stays also constituted a high proportion of stays among patients covered by Medicare (74.8 percent) and among the uninsured (67.6 percent).
• Maternal or neonatal stays constituted the largest proportion of hospitalizations among infants, younger adults, and patients covered by Medicaid.
  Neonatal stays constituted 91.9 percent of hospital stays among infants aged < 1 year. Nearly half of stays among patients aged 18–44 years (45.1 percent) and those covered by Medicaid (48.5 percent) were for maternal conditions.
• In the West, the proportion of maternal or neonatal stays was higher and the proportion of medical stays lower relative to the distribution within other U.S. regions.
  In the West maternal or neonatal stays accounted for more than one-quarter of all hospitalizations (27.4 percent) versus around 20 percent for the other regions (range: 19.0–21.9 percent). In addition, the West had a lower proportion of medical stays (50.0 percent) compared with the other regions (range: 56.7–59.6 percent).

Figure 2 presents the distribution of hospital stays by primary payer for 2012 and for 2 prior years (2003 and 2008), covering a 10-year time period.

Figure 2

Distribution of inpatient stays by primary payer, 2003, 2008, and 2012. Source: Agency for Healthcare Research and Quality (AHRQ), Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project (HCUP), National (Nationwide) Inpatient (more...)

• The share of hospital costs billed to private insurance decreased between 2003 and 2012.
  Between 2003 and 2012, the number of hospital stays billed to private insurance decreased from 13.6 to 11.2 million stays, representing a decrease from 36.6 to 30.6 percent of all hospitalizations. During this same time period, the share of stays billed to Medicaid increased from 6.8 to 7.6 million stays (an increase from 18.4 percent to 20.9 percent of all hospitalizations).

Figure 3 presents the rate of hospital inpatient stays across the nine U.S. Census divisions in 2012.

Figure 3

Rate of inpatient stays per 1,000 population by U.S. Census division, 2012. Source: Agency for Healthcare Research and Quality (AHRQ), Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project (HCUP), National Inpatient Sample (more...)

• The Pacific and Mountain divisions had the lowest rates of inpatient stays.
  The lowest hospitalization rates were in the Pacific and Mountain divisions (96.6 and 98.6 stays per 1,000 population, respectively). The West South Central division had a lower hospitalization rate (114.2 stays per 1,000 population) than did the East South Central and Middle Atlantic divisions (135.4 and 127.9 stays per 1,000 population, respectively).

Changes in utilization and costs of hospital stays, 2003–2012

Figure 4 presents overall changes in utilization and costs associated with hospital inpatient stays.

Figure 4

Average annual percentage change in hospital inpatient utilization and inflation-adjusted costs, 2003–2008 and 2008–2012. * Growth in mean and aggregate hospital costs was calculated using inflation-adjusted costs. Note: Data from 2008 (more...)

• Hospital costs increased while the rate of hospitalization and mean length of stay decreased over the decade from 2003 to 2012.
  The number of hospital stays increased 0.6 percent annually from 2003 to 2008, whereas the number of stays decreased an average of 1.1 percent annually between 2008 and 2012.
  The overall rate of hospitalization decreased over time, with an average annual decrease of 0.3 percent between 2003 and 2008 and an average annual decrease of 1.9 percent between 2008 and 2012.
  The length of a hospital stay decreased on average 0.2 percent per year between 2003 and 2012.
  Finally, mean inflation-adjusted hospital costs grew at a relatively steady rate, averaging 1.8 percent per year during both time periods. Aggregate inflation-adjusted hospital costs grew an average of 2.4 percent per year between 2003 and 2008 but slowed to a 0.7 percent average increase per year between 2008 and 2012.

Figure 5 presents the rate of stays by patient age for 2003, 2008, and 2012, along with the average annual percentage change for two consecutive 5-year time periods (2003–2008 and 2008–2012).

Figure 5

Rate of inpatient stays and change over time by patient age, 2003–2012. Note: Data from 2008 were used as end points in both the 2003–2008 and the 2008–2012 analyses. Source: Agency for Healthcare Research and Quality (AHRQ), Center (more...)

• The rate of hospitalization decreased between 2003 and 2012 overall and across patient subgroups.
  Between 2003 and 2012 the rate of hospitalization decreased from 128 stays per 1,000 population in 2003 to 116 stays per population in 2012. This decrease in the hospitalization rate occurred for all age groups. The rate of decrease was generally greater from 2008 to 2012 than from 2003 to 2008, with the exception of patients aged 1–17 years, who experienced a faster decline in hospitalization rate from 2003 to 2008.
  From 2008 through 2012, the rate of hospitalization decreased at the highest rate—almost 4 percent per year—for those aged 65 years and older.

Diagnoses, ICD-9-CM, major diagnostic categories (MDCs), and diagnosis-related groups (DRGs)

The principal diagnosis is that condition established after study to be chiefly responsible for the patient's admission to the hospital. Secondary diagnoses are concomitant conditions that coexist at the time of admission or develop during the stay.

ICD-9-CM is the International Classification of Diseases, Ninth Revision, Clinical Modification, which assigns numeric codes to diagnoses and procedures. There are approximately 14,000 ICD-9-CM diagnosis codes and approximately 4,000 ICD-9-CM procedure codes.

MDCs assign ICD-9-CM principal diagnosis codes to one of 25 general diagnosis categories. For this report, maternal hospital stays were identified using MDC 14 (pregnancy, childbirth, and the puerperium) and neonatal hospital stays were identified using MDC 15 (newborns and other neonates with conditions originating during the perinatal period).

DRGs comprise a patient classification system that categorizes patients into groups that are clinically coherent and homogeneous with respect to resource use. DRGs group patients according to diagnosis, type of treatment (procedure), age, and other relevant criteria. Each hospital stay has one assigned DRG. For this report, surgical stays were defined as valid O.R. procedures on the basis of DRG coding principles. Stays other than maternal/neonatal stays or surgical stays were considered medical stays.

Types of hospitals included in the HCUP National (Nationwide) Inpatient Sample

The National (Nationwide) Inpatient Sample (NIS) is based on data from community hospitals, which are defined as short-term, non-Federal, general, and other hospitals, excluding hospital units of other institutions (e.g., prisons). The NIS includes obstetrics and gynecology, otolaryngology, orthopedic, cancer, pediatric, public, and academic medical hospitals. Excluded are long-term care facilities such as rehabilitation, psychiatric, and alcoholism and chemical dependency hospitals. Beginning in 2012, long-term acute care hospitals are also excluded. However, if a patient received long-term care, rehabilitation, or treatment for psychiatric or chemical dependency conditions in a community hospital, the discharge record for that stay will be included in the NIS.

Unit of analysis

The unit of analysis is the hospital discharge (i.e., the hospital stay), not a person or patient. This means that a person who is admitted to the hospital multiple times in 1 year will be counted each time as a separate discharge from the hospital.

Costs and charges

Total hospital charges were converted to costs using HCUP Cost-to-Charge Ratios based on hospital accounting reports from the Centers for Medicare & Medicaid Services (CMS).³ Costs reflect the actual expenses incurred in the production of hospital services, such as wages, supplies, and utility costs; charges represent the amount a hospital billed for the case. For each hospital, a hospital-wide cost-to-charge ratio is used. Hospital charges reflect the amount the hospital billed for the entire hospital stay and do not include professional (physician) fees. For the purposes of this Statistical Brief, costs are reported to the nearest hundred.

Annual costs were inflation adjusted using the Gross Domestic Product (GDP) from the U.S. Department of Commerce, Bureau of Economic Analysis (BEA), with 2012 as the index base.⁴ That is, all costs are expressed in 2012 dollars.

Average annual percentage change

Average annual percentage change is calculated using the following formula:

Median community-level income

Median community-level income is the median household income of the patient's ZIP Code of residence. Income levels are separated into quartiles with cut-offs determined using ZIP Code demographic data obtained from the Nielsen Company. Patients in the first quartile are designated as having low income, and patients in the upper three quartiles are designated as having not low income. The income quartile is missing for patients who are homeless or foreign.

Payer

Payer is the expected primary payer for the hospital stay. To make coding uniform across all HCUP data sources, payer combines detailed categories into general groups:

• Medicare: includes patients covered by fee-for-service and managed care Medicare
• Medicaid: includes patients covered by fee-for-service and managed care Medicaid
• Private Insurance: includes Blue Cross, commercial carriers, and private health maintenance organizations (HMOs) and preferred provider organizations (PPOs)
• Uninsured: includes an insurance status of self-pay and no charge
• Other: includes Worker's Compensation, TRICARE/CHAMPUS, CHAMPVA, Title V, and other government programs

Hospital stays billed to the State Children's Health Insurance Program (SCHIP) may be classified as Medicaid, Private Insurance, or Other, depending on the structure of the State program. Because most State data do not identify patients in SCHIP specifically, it is not possible to present this information separately.

When more than one payer is listed for a hospital discharge, the first-listed payer is used.

Region

Region is one of the four regions defined by the U.S. Census Bureau:

• Northeast: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, and Pennsylvania
• Midwest: Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, and Kansas
• South: Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida, Kentucky, Tennessee, Alabama, Mississippi, Arkansas, Louisiana, Oklahoma, and Texas
• West: Montana, Idaho, Wyoming, Colorado, New Mexico, Arizona, Utah, Nevada, Washington, Oregon, California, Alaska, and Hawaii