Procedures in U.S. Hospitals, 1997: HCUP Fact Book No. 2

Foreword

The unprecedented volume and pace of change in the U.S. health care delivery system requires new information on health care and its delivery. The mission of the Agency for Healthcare Research and Quality (AHRQ) is to provide information on the health care system—on quality, outcomes, access, cost, and utilization—that decisionmakers can use to improve health care. To help fulfill this mission, the Agency develops and sponsors a number of databases, including the powerful Healthcare Cost and Utilization Project (HCUP). HCUP is a Federal-State-industry partnership to build a standardized health data system.

Through HCUP, AHRQ has taken a lead in developing databases, software tools, and statistical reports to inform policymakers, health system leaders, and researchers at the Federal, regional, and State levels. (Select for more information on HCUP.)

But for data to be useful, they must be disseminated in a timely, accessible way. In 1999, AHRQ launched HCUPnet, an interactive, Internet-based tool for identifying, tracking, analyzing, and comparing statistics on hospital utilization, outcomes, and charges. Menu-driven HCUPnet guides users in tailoring specific queries about hospital care online; with a click of a button, users receive answers within seconds.

A second new way we have developed to make these data more accessible and useful is the HCUP Fact Book series—reports that provide data about hospital care in the United States in an easy-to-use, readily accessible format. Each Fact Book will provide information about specific aspects of hospital care—the single largest component of our health care dollar. The first Fact Book provided an overview of hospital stays in the United States and types of conditions that were treated.

This second Fact Book provides information on procedures performed in U.S. hospitals:

• What are the most common procedures?
• What are the characteristics of patients who receive procedures?
• Which procedures are associated with the longest hospital stays, the most expensive hospitalizations, and the highest in-hospital mortality?
• Who is billed for procedures and what types of procedures are billed to these payers?
• What percentage of procedures is performed in high-volume hospitals?

Subsequent Fact Books will examine other topics such as hospital care for children, hospital care for women, and hospitals that serve the Medicaid and uninsured populations.

We invite you to tell us how you are using this Fact Book and other HCUP data and tools and to share suggestions on how HCUP products might be enhanced to further meet your needs. Please E-mail us at hcup@ahrq.gov or send a letter to the address below.

Irene Fraser, Ph.D.
Director
Center for Organization and Delivery Studies
Agency for Healthcare Research and Quality
2101 East Jefferson Street, Suite 605
Rockville, MD 20852

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Contributors

Without the following State partner organizations, the Healthcare Cost and Utilization Project would not be possible:

• Arizona Department of Health Services.
• California Office of Statewide Health Planning and Development.
• Colorado Health and Hospital Association.
• Connecticut Hospital Association (CHIME).
• Florida Agency for Health Care Administration.
• Georgia Hospital Association.
• Hawaii Health Information Corporation.
• Illinois Health Care Cost Containment Council.
• Association of Iowa Hospitals and Health Systems.
• Kansas Hospital Association.
• Maryland Health Services Cost Review Commission.
• Massachusetts Division of Health Care Finance and Policy.
• Missouri Hospital Industry Data Institute.
• New Jersey Department of Health and Senior Services.
• New York State Department of Health.
• Oregon Association of Hospitals and Health Systems and Office for Oregon Health Plan Policy and Research.
• Pennsylvania Health Care Cost Containment Council.
• South Carolina State Budget and Control Board.
• Tennessee Hospital Association.
• Utah Department of Health.
• Washington State Department of Health.
• Wisconsin Department of Health and Family Services.

In May 2000, these 22 HCUP State partners and AHRQ received the Secretary of Health and Human Services' Award for Distinguished Service for "leadership, teamwork, and creative thinking in increasing availability, utility, and value of data for policy-makers and researchers concerned with hospital quality, utilization and cost."

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Introduction

Americans had 35 million hospital stays in 1997, and during most of these stays patients underwent some type of procedure. "Procedures" are any type of invasive or noninvasive diagnostic or therapeutic interventions that appear on the discharge records of patients who stay in the hospital. Procedures can range from major operations such as coronary artery bypass graft (CABG) surgery, to diagnostic imaging such as computerized axial tomography (CT) scans, to noninvasive treatments such as alcohol and drug detoxification.

There is considerable variation in the thoroughness of coding for minor procedures, such as infusing intravenous antibiotics; so not all of these types of procedures are recorded and presented here.

Procedures on discharge records are coded using a classification system called "ICD-9-CM", which places procedures into about 3,500 different categories. For ease in reporting these statistics, this report uses Clinical Classification Software (CCS). CCS is a clinical grouper developed at AHRQ that assigns ICD-9-CM codes into about 230 unique categories.

This Fact Book summarizes information from the Nationwide Inpatient Sample (NIS), a database maintained by AHRQ that is uniquely suited to providing a comprehensive picture of hospital care in the United States. Because of its tremendous size (7.1 million records), the NIS can provide information on relatively uncommon diagnoses and procedures, as well as on subpopulations such as various age groups.

The NIS covers all patients discharged from hospitals, including:

• The uninsured.
• Those covered by public payers such as Medicare and Medicaid.
• Those with private insurance.

Unlike any other publicly available data source in the United States, the NIS also provides information on total hospital charges for all patients. The NIS includes short-term, non-Federal, community hospitals. General and specialty hospitals such as pediatric, obstetrics-gynecology, short-term rehabilitation, and oncology hospitals are included.

Long-term and psychiatric hospitals are excluded.

This report provides information on:

• Most common procedures, overall and by body system.
• Number of procedures done per hospital stay.
• Most common procedures, by age group and gender.
• Procedures associated with longest hospital stays.
• Procedures associated with highest overall charges.
• Procedures with highest in-hospital mortality.
• Charges billed to public or private payers, or uninsured.
• Procedures done in "high-volume" hospitals.

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Summary

There are over 35 million hospital stays in the United States every year accounting for about 40 percent of personal health expenditures. Most of these hospital stays—over 60 percent—involve some type of procedure; during many stays, multiple procedures are performed.

Understanding the types of procedures performed in U.S. hospitals is a foundation for assessing costs and quality of care. For example, recent studies have suggested a link between volume of procedures performed and the outcomes for certain procedures. This Fact Book provides an overview of procedures performed in U.S. hospitals and examines the most frequent procedures, those with the highest resource use, who is billed for which procedures, and the volume of procedures performed.

Most Common Procedures

• Procedures of the cardiovascular system are performed for 1 in 4 hospital stays. Nearly 4 million cardiac catheterizations are performed annually in U.S. hospitals—with 1 in 10 discharges receiving a cardiac catheterization.
• One in 5 discharges has procedures related to childbirth and pregnancy.
• One in 6 discharges has procedures that involve the digestive system.

Age and Gender

• Appendectomy is the most common procedure for children ages 1-17 years (performed for nearly 5 percent of discharges in this age group). Other top procedures for children and adolescents include treatments for fractures (2.8 percent), cancer chemotherapy (2.8 percent), and psychiatric therapy (1.7 percent).
• Laminectomy (back surgery, 3.3 percent), hysterectomy (5.4 percent), and oophorectomy (removal of ovaries, 3.5 percent) are among the most common procedures for patients ages 18-44. These procedures are also among the top 10 most common procedures for patients 45-64 years of age.
• Alcohol and drug detoxification is one of the top procedures performed for adults ages 18-44 (performed for 4.6 percent of discharges in this age group).
• More than 20 percent of patients 45-79 years of age admitted to the hospital receive diagnostic cardiac catheterization.
• Several heart procedures are in the top 10 for adults:
  • Diagnostic cardiac catheterization.
  • CABG.
  • Percutaneous transluminal coronary angioplasty (PTCA).
  • Extracorporeal circulation auxiliary to open heart procedures.
  • Diagnostic ultrasound of the heart.
  • Cardiac pacemaker procedures.
• Cholecystectomy and colonoscopy are among the top 10 procedures for females but not for males. Laminectomy/excision of intervertebral disk (surgery for back pain) is among the top 10 procedures for males but not for females.
• In the 18-44 age group, about three-fourths of all hospital stays are for women. Sixty percent of these stays are for pregnancy and childbirth.
• When procedures related to pregnancy and childbirth are included, they account for 8 of the top 10 procedures performed on patients ages 18-44.

Long-Stay and Expensive Procedures

• Organ transplantations are associated with some of the longest and most expensive hospital stays.
• Four of the top 10 most costly hospital stays are related to procedures on the cardiovascular system: heart transplantation, heart valve procedures, other operating room (OR) heart procedures, and other vascular bypass and shunt.

In-Hospital Deaths

• Three of the top 10 procedures associated with the highest rates of in-hospital mortality are related to the respiratory system:
  • Respiratory intubation and mechanical ventilation.
  • Incision of pleura.
  • Diagnostic bronchoscopy.
• Other procedures associated with large numbers of in-hospital deaths indicate the presence of organ failure and critical illness:
  • Swan-Ganz catheterization.
  • Enteral and parenteral nutrition.
  • Hemodialysis.

Charges

• Medicare is billed for about three-fourths of all hospital stays that involve a cardiac pacemaker or defibrillator procedure and about half of all hospital stays involving cardiac catheterization, CABG, diagnostic ultrasound of heart, and PTCA.
• Medicare is billed for over 65 percent of all hospital stays during which patients receive hemodialysis (treatment for renal failure) because treatment for end-stage renal disease is covered by Medicare, regardless of the age of the patient.
• Seven of the top 10 procedures billed to Medicaid are for pregnancy, childbirth, and newborn infant care. Medicaid is billed for about one-third of all hospital stays involving these childbirth procedures.
• Among uninsured patients, 4 of the top 10 procedures are related to pregnancy, childbirth, and newborn infant care.
• One in 6 hospital stays for alcohol and drug detoxification is uninsured.

Procedures in High-Volume Hospitals

• Recent research suggests that for some procedures, postoperative mortality is lower at hospitals that perform a high volume of these procedures.
• Nearly 60 percent of hospitals that do heart transplantations are "high-volume" hospitals (based on thresholds defined in previous studies). About 55 percent of hospitals doing lower extremity arterial bypass and 50 percent of hospitals doing coronary angioplasty reach the high-volume threshold for that procedure.
• For 6 out of 10 procedures studied here, less than 20 percent of hospitals would be considered high-volume providers.
• Over 90 percent of patients receiving lower extremity arterial bypass and around 85 percent of patients receiving coronary angioplasty and heart transplantation receive these procedures in high-volume hospitals.
• About 30 percent of heart surgery for children, 38 percent of all CABG surgery, and nearly half of all patients receiving elective abdominal aortic aneurysm repair, carotid endarterectomy, and pancreatic cancer surgery receive these procedures in low-volume hospitals.
• For esophageal cancer surgery and cerebral aneurysm repair, most patients receive their procedures at low-volume hospitals.

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Findings

Most Common Procedures

What Are the Most Common Procedures Performed in U.S. Hospitals?

• Nearly 4 million cardiac catheterizations are performed in U.S. hospitals. About 1 in 10 hospitalized patients receives a cardiac catheterization.
• Four of the top procedures are related to the heart: diagnostic cardiac catheterization, CABG, diagnostic ultrasound of the heart, and PTCA. This reflects the high burden of cardiovascular disease in the Nation.
• Four of the most frequent procedures are related to pregnancy and childbirth: procedures to assist delivery, circumcision, repair of obstetric laceration, and fetal monitoring.
• About 1 in 25 patients receives respiratory intubation and mechanical ventilation—procedures generally provided to critically ill patients in the intensive care unit. These patients include newborns in respiratory distress and adults with respiratory failure, pneumonia, myocardial infarction, and stroke.
• Five of the top procedures are diagnostic: diagnostic cardiac catheterization, upper gastrointestinal endoscopy and biopsy, diagnostic ultrasound of heart, CT scan of head, and colonoscopy and biopsy.
• Laminectomy/excision of intervertebral disk (surgery for back pain) accounts for over a half million hospital discharges per year.

For more information, select Table 1, Most Common Procedures (Text Version).

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Body System

What Type of Procedures Do Patients Receive by Body System?

• Over 1 in 4 hospital stays has procedures that involve the cardiovascular system.
• One in 5 discharges has procedures related to pregnancy and childbirth.
• About 1 in 6 discharges has procedures that involve the digestive system.

Select Figure 1 (9 KB), Discharges by Body System.

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Procedures per Stay

How Many Procedures Do Patients Receive per Hospital Stay?

• Three of 5 patients in U.S. hospitals receive at least one procedure during their hospital stay. One in 5 receives three or more.
• Patients who receive at least one procedure average 2.3 procedures during their hospital stay (data not shown).
• Patients who receive no procedure are most commonly newborn infants or medical patients—patients with conditions such as pneumonia, congestive heart failure, depression, and chronic obstructive pulmonary disease—who are in the hospital for medical reasons such as stabilization, medication, and observation.

Select Figure 2 (6 KB), Procedures per Stay.

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Age and Gender

What Are the Most Common Procedures by Age?

Appendectomy is the most common procedure for children ages 1-17, performed for nearly 5 percent of all hospitalized children. Other top procedures include treatments for fractures, cancer chemotherapy, and psychiatric therapy.
• Laminectomy (back surgery), hysterectomy and oophorectomy (removal of ovaries) are among the most common procedures for patients ages 18-64. About 3 percent of all hospital stays in this age group involve laminectomy. Over 5 percent of all hospital stays for patients ages 18-44 are for hysterectomy.
• Alcohol and drug detoxification is one of the top procedures performed for adults 18-44 years of age. Nearly 5 percent of all hospital stays in this age group involve alcohol and drug detoxification.
• More than 20 percent of patients 45-79 years of age admitted to the hospital receive diagnostic cardiac catheterization.
• Several heart procedures are in the top 10 for adults:
  • Diagnostic cardiac catheterization.
  • CABG.
  • PTCA.
  • Extracorporeal circulation auxiliary to open heart procedures.
  • Diagnostic ultrasound of the heart.
  • Cardiac pacemaker procedures.
• About 6 percent of stays for infants and for adults ages 65-79 involve mechanical ventilation.
• Three percent of hospital stays for patients 80 and older are for the treatment of hip fractures. Colonoscopy is performed during about 3 percent of all hospital stays among patients 65 and older.
• When obstetrical procedures are included, 8 of the top 10 procedures performed on all patients 18-44 (male and female) are related to pregnancy and childbirth (data not shown). About 74 percent of all hospital stays in this age group are for women, and 60 percent of these stays are for pregnancy and childbirth.

Select Table 2, Most Common Procedures by Age Group (Text Version).

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How Do Procedures Received Compare by Gender?

• Two of the top 10 procedures for females are procedures of the reproductive system: hysterectomy and oophorectomy (removal of ovaries).
• Four of the top 10 procedures for males pertain to the cardiovascular system—three are therapeutic and one is diagnostic. In contrast, two of the top 10 procedures for females pertain to the cardiovascular system—both are diagnostic.
• Cholecystectomy and colonoscopy are among the top 10 procedures for females but not for males.
• Laminectomy/excision of intervertebral disk—surgery for back pain— is a top 10 procedure for males but not for females.

Select Table 3, Top 10 Procedures by Gender (Text Version).

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Long-Stay and Expensive and Procedures

Which Procedures Are Associated with the Longest Hospital Stays?

• Bone marrow and other organ transplantations (e.g., liver, heart) are associated with some of the longest hospital stays.
• Other procedures associated with long hospital stays are indicative of patients with serious chronic illnesses. Ileostomy, gastrostomy, and enteral/parenteral nutrition are performed for very ill patients requiring extensive care. Tracheostomy is performed for patients who are often dependent on mechanical ventilation or have need for other types of extended care.
• The hospitalizations with the longest lengths of stay are not very common. Collectively, these 10 procedures represent less than 2 percent of all hospital stays.

Select Figure 3 (12 KB), Procedures Associated with Longest Hospital Stays.

Which Procedures Are Associated with the Most Costly Hospital Stays?

• Four of the top 10 most costly hospital stays are related to procedures on the cardiovascular system:
  • Heart transplantation (part of other organ transplantation).
  • Heart valve procedures.
  • Other operating room (OR) heart procedures (e.g., implant of pulsation balloon, pericardiotomy).
  • Other vascular bypass and shunt (e.g., intra-abdominal venous shunt, aorta-renal bypass, aorta-subclavian-carotid bypass).
• Bone marrow and organ transplantations (e.g., heart, liver, kidney) are associated with some of the most expensive hospital stays.
• Some procedures are not in themselves costly but are associated with critical illness and expensive care, for example, a long stay in an intensive care unit. These include:
  • Tracheostomy.
  • Swan-Ganz catheterization.
  • Other OR respiratory procedures (e.g., reopening of recent thoracotomy site, decortication of lung, scarification of pleura).
• Four of the procedures performed during the most expensive hospital stays also are among those with the longest lengths of hospitalization:
  • Other organ transplantation (e.g., heart, liver).
  • Tracheostomy.
  • Bone marrow transplantation.
  • Ileostomy/enterostomy.

Select Figure 4 (15 KB) Procedures Associated with Most Costly Hospital Stays.

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In-Hospital Deaths

Which Procedures Are Performed Most Often during Hospital Stays Ending in Death?

• The most common procedure performed during hospital stays that end in death is conversion of cardiac rhythm, which indicates an unsuccessful attempt at resuscitation.
• The second most common procedure associated with high in-hospital mortality is respiratory intubation and mechanical ventilation. This procedure is done for critical conditions such as respiratory failure, myocardial infarction, stroke, pneumonia, and septicemia.
• Procedures that indicate the presence of organ failure and critical illness include Swan-Ganz catheterization, enteral and parenteral nutrition, hemodialysis, and blood transfusions.
• It is important to note that these top 10 procedures are markers of severe underlying disease and are not the cause of death.

Select Table 4, Procedures Associated with Highest Inpatient Mortality (Text Version).

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Charges

What Are the Differences in How Procedures Are Billed, by Body System?

• Obstetrical procedures comprise 38 percent of all procedures billed to Medicaid, 28 percent of those billed to private insurers, and 22 percent of those performed during uninsured hospital stays.
• Cardiovascular procedures account for more than 2 in 5 of all procedures billed to Medicare, 1 in 7 of those billed to Medicaid, and 1 in 5 of those billed to private insurers or uninsured.
• Procedures of the digestive system are the second most common category of procedures for Medicare patients, performed on more than 1 in 5 patients.

Select Figure 5 (17 KB), How Procedures Are Billed, by Body System (Text Version).

What Are the Most Common Procedures for Hospital Stays Billed to Medicare?

• Five out of the top 10 procedures billed to Medicare are related to the heart: diagnostic cardiac catheterization, CABG, cardiac pacemaker or cardioverter/defibrillator procedure, diagnostic ultrasound of heart, and PTCA.
• Medicare is billed for about three-fourths of all hospital stays that involve a cardiac pacemaker or defibrillator procedure.
• Medicare is billed for over 65 percent of all hospital stays that involve hemodialysis (treatment for renal failure) because treatment for end-stage renal disease is covered by Medicare, regardless of the patient's age.
• Medicare is billed for roughly half of all hospital stays involving cardiac catheterization, blood transfusion, upper gastrointestinal endoscopy, CABG, diagnostic ultrasound of heart, and PTCA.

Select Table 5, Most Common Procedures for Hospital Stays Billed to Medicare (Text Version).

What Are the Most Common Procedures for Hospital Stays Billed to Medicaid?

• Seven of the top 10 procedures billed to Medicaid are for pregnancy, childbirth, and newborn infant care. Overall, Medicaid is billed for about one-third of all hospital stays involving these childbirth procedures.
• Medicaid is billed for 1 in 5 hospital stays involving respiratory intubation and mechanical ventilation.
• Medicaid's share of hospital stays involving diagnostic cardiac catheterization—7.2 percent—is less than half its share of stays requiring blood transfusions—15.2 percent.

Select Table 6, Most Common Procedures for Hospital Stays Billed to Medicaid (Text Version).

What Are the Most Common Procedures for Hospital Stays Billed to Private Insurance?

• Seven of the top 10 procedures billed to private insurers are related to pregnancy, childbirth, and newborn infant care. Private payers are billed for over half of these types of procedures.
• Private insurers are billed for just over a third of hospital stays in which diagnostic cardiac catheterization is performed, indicating that government (i.e., Medicare) bears the largest burden of paying for this most common procedure.
• Private insurers are billed for 7 in 10 hospital stays for hysterectomy.

Select Table 7, Most Common Procedures for Hospital Stays Billed to Private Insurance (Text Version).

What Are the Most Common Procedures for Uninsured Hospital Stays?

• Among uninsured patients, 4 of the top 10 procedures are related to pregnancy, childbirth, and newborn infant care: procedures to assist delivery, fetal monitoring, repair of current obstetric laceration, and circumcision.
• Seventeen percent of hospital stays for alcohol and drug detoxification are not covered by insurance.

Select Table 8, Most Common Procedures for Uninsured Hospital Stays (Text Version).

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Procedures in High-Volume Hospitals

Do Patients in Hospitals that Do Higher Numbers of Certain Procedures Have Lower Mortality Rates?

• Recent research* suggests that the outcomes, or results, of certain procedures are related to how many of them are performed in a hospital. These procedures often require high-technology support; but the exact nature of this "volume-to-outcome" relationship is not well understood.
• Hospitals that perform more than a specific number of certain procedures have fewer in-hospital deaths for those particular procedures. This "threshold number" varies with the type of procedure.
• For example, hospitals where at least 500 CABG procedures are performed each year have significantly lower mortality rates for CABG than hospitals performing fewer than 500. Hospitals doing nine or more heart transplantations annually have fewer in-hospital deaths for this procedure than hospitals doing fewer than nine.

* Adapted from Dudley R, Johansen K, Brand R, et al. Selective referral to high-volume hospitals: Estimating potentially avoidable deaths. JAMA 2000 Mar 1;283(9):1159-66.

Select Table 9, Ten Procedures with Evidence of a Volume-to-Outcome Link (Text Version).

What Share of the Nation's Hospitals are High-Volume Providers of Specific Procedures?

• About 60 percent of hospitals that do heart transplantations, 55 percent of those that do lower extremity arterial bypass, and half of those that do coronary angioplasty are high-volume providers.
• Only about one-third of hospitals that perform coronary artery bypass graft surgery are high-volume providers.
• Fewer than 1 in 5 hospitals doing carotid endarterectomy and 1 in 6 performing pediatric heart surgery and abdominal aortic aneurysm repair are high-volume hospitals.
• Roughly 1 in 10 hospitals performing pancreatic cancer surgery, 1 in 15 doing cerebral aneurysm surgery, and 1 in 20 doing esophageal cancer surgery are high-volume providers.

Select Figure 6 (10 KB), What Share of the Nation's Hospitals are High-Volume Providers for Specific Procedures?

What Share of Patients Receive Procedures in High-Volume Hospitals?

• Over 90 percent of patients receiving lower extremity arterial bypass and about 85 percent of patients undergoing coronary angioplasty and heart transplantations receive them in high-volume hospitals.
• Just over 70 percent of heart surgery procedures for children are performed in high-volume hospitals.
• Less than two-thirds of coronary artery bypass graft surgeries are done in high-volume hospitals.
• Over half of all abdominal aortic aneurysm repair, carotid endarterectomy, and pancreatic cancer surgeries are done in high-volume hospitals.
• Only a fourth of surgical procedures for esophageal cancer and just over a third of those for cerebral aneurysm repair are done in high-volume hospitals.

Select Figure 7 (10 KB), What Share of Patients Receive Procedures in High-Volume Hospitals?

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Source of Data for this Report

The data presented in this report are drawn from the Healthcare Cost and Utilization Project (HCUP), a Federal-State-industry partnership to build a multi-State health care data system. This partnership is sponsored by the Agency for Healthcare Research and Quality and is managed by staff in AHRQ's Center for Organization and Delivery Studies. HCUP is based on data collected by individual States and forwarded to AHRQ by the States. HCUP would not be possible without State data collection projects and their partnership with AHRQ.

For 1997, 22 State organizations contributed their data to AHRQ where all data are edited and transformed into a uniform format. The uniform data in HCUP databases make possible comparative studies of health care services and the use and cost of hospital care, including:

• The effects of market forces on hospitals and the care they provide.
• Variations in medical practice.
• The effectiveness of medical technology and treatments.
• Use of services by special populations.

HCUP includes short-term, non-Federal, community hospitals (general and specialty hospitals such as pediatric, obstetrics-gynecology, short-term rehabilitation, and oncology hospitals are included). Long-term care and psychiatric hospitals are excluded.

HCUP includes two sets of inpatient databases for health services research. The State Inpatient Databases (SID) for 1997 cover inpatient care in community hospitals in 22 States and include nearly 60 percent of all hospital discharges in the United States. The Nationwide Inpatient Sample includes all discharges from a sample of about 1,000 hospitals drawn from the SID, adjusted to approximate a national sample.

This report is based on data from the NIS. The NIS approximates a 20-percent sample of U.S. community hospitals, as defined by the American Hospital Association (AHA). The NIS for 1997 includes information from 7.1 million discharges that were weighted to obtain estimates that represent the total number of inpatient hospital discharges in the United States (35.4 million).

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Methods

The Clinical Classification Software (CCS), developed by AHRQ, has been used throughout this Fact Book to aggregate procedure codes into a limited number of categories. Procedures recorded on hospital discharge records are coded using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), Fifth Edition. Although ICD-9-CM may be used to provide descriptive statistics, aggregating similar diagnoses or procedures into clinically meaningful categories, such as the CCS, can be more helpful. Select for more information.

Frequencies and rankings of procedures are based on all-listed procedures; that is, all procedures listed on the discharge record. The unit of analysis is the inpatient stay, rather than the patient or procedure. All discharges have been weighted to produce national estimates.

Total charges in HCUP data are the amount the hospital charged or billed for the entire hospital stay and do not reflect charges for the individual procedures. Charges do not necessarily reflect reimbursements or costs and are generally higher than costs. Hospital charges do include professional (physician) fees. Charge data were present for 98 percent of all discharges.

Because the NIS is limited to inpatient hospital data, procedures performed in outpatient or ambulatory care settings are not reflected here.

Many medical terms are used throughout this report. For help in understanding these terms, refer to the Glossary.

Acknowledgments

Thanks to Suzanne Worth at Social and Scientific Systems for her invaluable assistance in statistical programming and to DonnaRae Castillo, AHRQ Office of Health Care Information, for editorial assistance.

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AHRQ Publication No. 01-0016
Current as of February 2001

Internet Citation:

Procedures in U.S. Hospitals, 1997. HCUP Fact Book No. 2. Elixhauser A, Klemstine K, Steiner C, Bierman A. February 2001, AHRQ Publication No. 01-0016. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/data/hcup/factbk2/factbk2.htm

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