User Support

April 2013

Audrey J. Weiss, Ph.D., Anne Elixhauser, Ph.D., and Claudia Steiner, M.D., M.P.H.



Introduction

Readmissions—revisits to the hospital within a certain time frame following an initial inpatient stay—are receiving increasing attention as a measure of quality of care and a potential source for reducing healthcare costs.¹ Although not all rehospitalizations can be prevented, many readmissions could be avoided with improvements in the quality of hospital care provided during, transitioning from, and following the inpatient stay.

Research indicates that nearly one in five Medicare patients are readmitted to the hospital within 30 days, about 90 percent of these readmissions are unplanned, and the costs to Medicare are more than $17 billion.² The Patient Protection and Affordable Care Act (Section 3025) mandates a hospital readmissions reduction program whereby Medicare payments will be reduced for hospitals with excessive readmissions.³

Prior research has offered select views of readmissions for general surgery⁴ or high-risk surgery,⁵ and some studies have focused on readmissions for specific surgical procedures such as percutaneous coronary intervention (PCI/PTCA).^6,7 However, relatively limited information is available about readmissions by procedure. This Statistical Brief provides an overview of 30-day all-payer, all-cause readmissions to U.S. hospitals for a range of inpatient procedures in 2010. It presents the most comprehensive national estimates on readmissions by procedure that is available to date.

In this Statistical Brief, readmission was defined as a subsequent hospital admission within 30 days following an original admission (or index stay) with a major operating room procedure that occurred from January through November 2010. All-cause readmissions were examined; thus, readmissions may or may not include procedures that were listed during the index stay. Readmissions were tracked across the same or different hospitals. Some readmissions may be planned or unavoidable-no attempt was made to remove these types of readmissions from the analysis.

Readmission rates using Healthcare Cost and Utilization Project (HCUP) data are provided for the most frequent procedures treated in U.S. hospitals during 2010 and for the procedures with the highest readmission rates. All estimates were taken from HCUPnet, the online query system that provides free access to information from HCUP.⁸ For a subset of procedures, readmission rates are presented by age group and expected payer (insurance status). Patients younger than 1 year were excluded from this analysis. Readmission rates were calculated without risk adjustment.

Appendix A provides detailed information on readmission rates for most procedures performed in U.S. hospitals in 2010. The table provides information on the number of index stays for each procedure, the number of all-cause readmissions within 30 days, and the percentage of index stays that were followed by a readmission within 30 days for any cause. Excluded were nonspecific procedures and any procedures with fewer than 5,000 index stays or fewer than 500 readmissions. In general, procedures are organized by body system in this table.

Findings

Readmission rates for the most frequent procedures
Table 1 lists the 30 most frequent procedures performed in U.S. hospitals, with their 30-day readmission rates. Readmission rates for these high-volume procedures varied from a low of 2.0 percent (Cesarean section and ligation of fallopian tubes) to a high of 22.8 percent (amputation of a lower extremity). The most frequent procedures and their readmission rates were Cesarean section (2.0 percent), knee arthroplasty (5.0 percent), percutaneous coronary angioplasty (12.9 percent), laminectomy (6.7 percent), and spinal fusion (6.8 percent).

Among the most frequent procedures, as many as one in five patients were readmitted within 30 days. The highest readmission rates were for amputation of a lower extremity (22.8 percent); debridement of a wound, infection, or burn (19.1 percent); heart valve procedures (18.5 percent); and small bowel resection (18.1 percent). The lowest readmission rates were for procedures related to childbirth and the reproductive organs (Cesarean section, 2.0 percent; ligation of fallopian tubes, 2.0 percent; repair of cystole and rectocele, obliteration of vaginal vault, 2.6 percent) or genitourinary incontinence (3.0 percent).

Procedures with the highest readmission rates
Table 2 lists procedures ranked by the highest readmission rates. Diagnostic procedures (e.g., exploratory surgery, biopsy) and nonspecific categories are excluded from this table. Diagnostic procedures are included in the Appendix.

Across all inpatient procedures, 30-day readmission rates reached a high of almost one in three patients for kidney transplant (29.1 percent) and ileostomy and other enterostomy (29.1 percent). Three other procedures—those to create access for hemodialysis (27.4 percent), nephrotomy and nephrostomy (24.0 percent), and tracheostomy (23.9 percent)—had readmission rates of approximately one in four patients.

Among the 30 procedures with the highest readmission rates, 14 of them also are among the 30 most frequent procedures performed in the U.S. Percutaneous coronary angioplasty (78,038 patients; 12.9 percent readmission rate) has the 26th highest readmission rate and is the 3rd most common procedure. Colorectal resection (43,388 patients; 14.8 percent readmission rate) has the 21st highest readmission rate and is the 12th most common procedure. Excision or lysis of peritoneal adhesions (42,126 patients; 12.3 percent readmission rate) has the 27th highest readmission rate and is the 9th most common procedure. CABG (35,484 patients; 15.1 percent readmission rate) has the 20th highest readmission rate and is the 16th most common procedure. Treatment of hip/femur fracture (33,049 patients; 11.9 percent readmission rate) has the 28th highest readmission rate and is the 17th most common procedure.

Readmission rates by age and insurance status for selected procedures
Figures 1–6 provide details on 30-day all-cause readmission rates for the six procedures from Table 2 that involved more than 100,000 index stays and had overall readmission rates of at least 15 percent.

Figure 1 depicts readmission rates for amputation of a lower extremity. Readmission rates increased with age, ranging from 17.0 percent among patients aged 18–44 years to 25.8 percent among patients aged 65 years and older. The highest readmission rate was seen for patients with an expected payer of Medicare (25.5 percent) compared to 22.1 percent for Medicaid-covered patients, 16.9 percent for privately insured patients, and 12.9 percent for the uninsured.

Readmission rates for debridement of a wound, infection, or burn are shown in figure 2. Readmission rates progressively were higher with advancing age, increasing from 13.7 percent for 18–44 year olds to 23.7 percent for those aged 65 years and older. The readmission rate was highest for Medicare-covered patients (24.1 percent). The readmission rate for Medicaid-covered patients was 18.2 percent and for privately insured patients it was 13.5 percent, whereas for uninsured patients it was only 9.0 percent.

Figure 3 shows readmission rates for heart valve procedures. Readmission rates were highest for those aged 65 years and older (20.0 percent) and lower for those in the two younger age groups (16.5–16.7 percent). Readmission rates were identical for patients with an expected payer of Medicare or Medicaid (20.5 percent), which was more than 50 percent higher than for privately insured patients (13.3 percent).

Readmission rates for incision and excision of the central nervous system (CNS) are depicted in figure 4. The highest readmission rate was for patients aged 65 years and older (18.4 percent), followed by patients aged 45–64 years (15.7 percent). Readmission rates were lowest and similar for the two youngest age groups (13.0–13.4 percent). Readmission rates were highest for patients covered by Medicare (18.8 percent), followed by Medicaid (16.7 percent) and private insurance (13.3 percent).

Figure 5 presents readmission rates for procedures related to a cardiac pacemaker or cardioverter/defibrillator. Readmission rates generally were similar for all adult age groups. Readmission rates were highest and similar for Medicare-covered (16.4 percent) and Medicaid-covered (16.5 percent) patients and lowest for privately insured patients (11.8 percent).

Finally, readmission rates for coronary artery bypass graft (CABG) are shown in figure 6. Readmission rates were highest for patients aged 65 years and older (16.7 percent), followed by those in age groups 18–44 (14.1 percent) and 45–64 (12.9 percent). The readmission rate was highest for patients with an expected payer of Medicaid (19.2 percent) or Medicare (17.3 percent) and lowest for the uninsured (12.1 percent) and those with private insurance (10.4 percent).

Overall, across select procedures with high volume (more than 100,000 index stays) and high readmission rates (at least 15 percent), the 30-day readmission rate consistently was higher for patients aged 65 years and older than for younger adults. In terms of payer, patients with Medicare and Medicaid coverage also consistently had higher readmission rates than patients with private insurance or those who were uninsured.

Data Source

The estimates in this Statistical Brief are based on a readmissions analysis file that was created with the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases (SID). These databases include reliable, verified synthetic patient identifiers that can be used to track a person across hospitals within a State. Estimates were taken from HCUPnet, the online query system that provides free access to information from HCUP: https://datatools.ahrq.gov/hcupnet. HCUPnet provides access to health statistics and information on hospital inpatient and emergency department utilization, and it includes analytic tables using the readmissions analysis file. HCUPnet contains additional detailed results and sortable tables that provide instant information on readmissions to the hospital within 30 days of discharge.

For 2010, readmissions data were available from 18 States: Alaska, Arkansas, California, Florida, Georgia, Hawaii, Louisiana, Massachusetts, Mississippi, Missouri, Nebraska, New Mexico, New York, South Carolina, Tennessee, Utah, Virginia, and Washington. These 18 States are geographically dispersed and account for 46 percent of the total U.S. resident population and 45 percent of the total U.S. hospitalizations. The readmissions analysis file included 14.0 million unweighted discharges.

The study population in this readmissions analysis file included discharges from community, nonrehabilitation, nonspecialty hospitals. Weights for national estimates were developed using poststratification on hospital characteristics (Census region, urban-rural location, teaching capabilities, bed size, and control/ownership) and patient age groups.

Definitions

Procedures, ICD-9-CM, and Clinical Classifications Software (CCS)
All-listed procedures include all procedures performed during the hospital stay whether for definitive treatment or for diagnostic or exploratory purposes.

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

CCS categorizes procedure codes into clinically meaningful categories.⁹ This "clinical grouper" makes it easier to quickly understand patterns of procedure use. CCS categories identified as "Other" typically are not reported; these categories include miscellaneous, otherwise unclassifiable procedures that may be difficult to interpret as a group.

Readmissions
The 30-day readmission rate is defined as the number of admissions for each procedure for which there was at least one subsequent hospital admission within 30 days, divided by the total number of admissions from January through November 2010. That is, when patients are discharged from the hospital, they are followed for 30 days in the data. If any readmission to the same or different hospital occurs during this time period, the admission is counted as a readmission. No more than one readmission is counted within the 30-day period, because the outcome measure assessed is "percentage of admissions who are readmitted." If a patient was transferred to a different hospital on the same day or was transferred within the same hospital, the two events were combined as a single stay and the second event was not counted as a readmission; that is, transfers were not considered a readmission. In the case of admissions for which there was more than one readmission in the 30-day period, the data presented in this Statistical Brief reflect the characteristics and costs of the first readmission.

Every qualifying hospital stay is counted as a separate index (starting point) admission. Thus, a single patient can be counted multiple times during the course of the January through November observation period. In addition, index admissions do not require a prior "clean period" with no hospitalizations; that is, a hospital stay may be a readmission for a prior stay and the index admission for a subsequent readmission. Admissions were disqualified from the analysis as index admissions if they could not be followed for 30 days for one of the following reasons: (1) admissions in which the patient died in the hospital, (2) admissions missing information on length of stay, and (3) admissions discharged in December 2010.

Types of hospitals included in HCUP
HCUP 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). HCUP data include obstetrics and gynecology, otolaryngology, orthopedic, cancer, pediatric, public, and academic medical hospitals. Excluded are long-term care, rehabilitation, psychiatric, and alcoholism and chemical dependency hospitals.

Payer (Insurance Status)
Payer is the expected payer for the hospital stay. To make coding uniform across all HCUP data sources, payer combines detailed categories into more 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. Patients covered by the State Children's Health Insurance Program (SCHIP) may be included here. Because most State data do not identify SCHIP patients specifically, it is not possible to present this information separately.
• Private Insurance: includes Blue Cross, commercial carriers, and private health maintenance organizations (HMOs) and preferred provider organizations (PPOs)
• Other: includes Worker's Compensation, TRICARE/CHAMPUS, CHAMPVA, Title V, and other government programs
• Uninsured: includes an insurance status of "self-pay" and "no charge."

For this Statistical Brief, a hierarchy was used to assign the payer category based on the primary and secondary expected payer:

• If the primary or secondary expected payer indicates Medicare, then the payer category is assigned to Medicare. This categorization includes patients who are dually eligible for Medicare and Medicaid under Medicare.
• If not Medicare and the primary or secondary expected payer indicates Medicaid, then the payer category is Medicaid.
• If not Medicare or Medicaid and the primary or secondary expected payer indicates private insurance, then the payer category is private.
• If not Medicare, Medicaid, or private and the primary expected payer indicates self-pay or no charge, then the payer category is uninsured.
• Stays for other types of payers are not reported in this Statistical Brief because this is a mixed payer group and small numbers.

For this Statistical Brief, categorization of readmission counts by expected payer was based on the index stay.

About HCUP

HCUP is a family of powerful healthcare databases, software tools, and products for advancing research. Sponsored by the Agency for Healthcare Research and Quality (AHRQ), HCUP includes the largest all-payer encounter-level collection of longitudinal healthcare data (inpatient, ambulatory surgery, and emergency department) in the United States, beginning in 1988. HCUP is a Federal-State-Industry Partnership that brings together the data collection efforts of many organizations—such as State data organizations, hospital associations, private data organizations, and the Federal government—to create a national information resource.

HCUP would not be possible without the contributions of the following data collection Partners from across the United States:

Alaska State Hospital and Nursing Home Association
Arizona Department of Health Services
Arkansas Department of Health
California Office of Statewide Health Planning and Development
Colorado Hospital Association
Connecticut Hospital Association
Florida Agency for Health Care Administration
Georgia Hospital Association
Hawaii Health Information Corporation
Illinois Department of Public Health
Indiana Hospital Association
Iowa Hospital Association
Kansas Hospital Association
Kentucky Cabinet for Health and Family Services
Louisiana Department of Health and Hospitals
Maine Health Data Organization
Maryland Health Services Cost Review Commission
Massachusetts Center for Health Information and Analysis
Michigan Health & Hospital Association
Minnesota Hospital Association
Mississippi Department of Health
Missouri Hospital Industry Data Institute
Montana MHA - An Association of Montana Health Care Providers
Nebraska Hospital Association
Nevada Department of Health and Human Services
New Hampshire Department of Health & Human Services
New Jersey Department of Health
New Mexico Department of Health
New York State Department of Health
North Carolina Department of Health and Human Services
North Dakota (data provided by the Minnesota Hospital Association)
Ohio Hospital Association
Oklahoma State Department of Health
Oregon Association of Hospitals and Health Systems
Oregon Health Policy and Research
Pennsylvania Health Care Cost Containment Council
Rhode Island Department of Health
South Carolina Budget & Control Board
South Dakota Association of Healthcare Organizations
Tennessee Hospital Association
Texas Department of State Health Services
Utah Department of Health
Vermont Association of Hospitals and Health Systems
Virginia Health Information
Washington State Department of Health
West Virginia Health Care Authority
Wisconsin Department of Health Services
Wyoming Hospital Association

About the SID

The HCUP State Inpatient Databases (SID) are hospital inpatient databases from data organizations participating in HCUP. The SID contain the universe of the inpatient discharge abstracts in the participating HCUP States, translated into a uniform format to facilitate multistate comparisons and analyses. Together, the SID encompass more than 95 of all U.S. community hospital discharges in 2010. The SID can be used to investigate questions unique to one State, to compare data from two or more States, to conduct market area variation analyses, and to identify State-specific trends in inpatient care utilization, access, charges, and outcomes.

About HCUPnet

HCUPnet is an online query system that offers instant access to the largest set of all-payer healthcare databases publicly available. HCUPnet has an easy step-by-step query system, allowing for tables and graphs to be generated on national and regional statistics as well as trends for community hospitals in the United States. HCUPnet generates statistics using data from HCUP's Nationwide Inpatient Sample (NIS), the Kids' Inpatient Database (KID), the Nationwide Emergency Department Sample (NEDS), the State Inpatient Databases (SID), and the State Emergency Department Databases (SEDD).

For More Information

For more information about HCUP, visit http://www.hcup-us.ahrq.gov/.

For additional HCUP statistics, visit HCUPnet, our interactive query system, at https://datatools.ahrq.gov/hcupnet. HCUPnet provides ready-to-use tables on readmission rates by condition and procedure (using Clinical Classification Software categories), diagnosis related groups (DRGs), and major diagnostic categories (MDCs).

Suggested Citation

Weiss AJ (Truven Health Analytics), Elixhauser A (AHRQ), Steiner C (AHRQ). Readmissions to U.S. Hospitals by Procedure, 2010. HCUP Statistical Brief #154. April 2013. Agency for Healthcare Research and Quality, Rockville, MD. http://www.hcup-us.ahrq.gov/reports/statbriefs/sb154.pdf.

Acknowledgements

The authors would like to acknowledge the contributions of Marguerite Barrett and Minya Sheng for work on programming.

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AHRQ welcomes questions and comments from readers of this publication who are interested in obtaining more information about access, cost, use, financing, and quality of healthcare in the United States. We also invite you to tell us how you are using this Statistical Brief 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 Delivery, Organization, and Markets
Agency for Healthcare Research and Quality
540 Gaither Road
Rockville, MD 20850



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⁸ https://datatools.ahrq.gov/hcupnet
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