May 2017
(Revised February 2018)*
(Revised July 2020)**
Surgeries in Hospital-Based Ambulatory Surgery and Hospital Inpatient Settings, 2014
Claudia A. Steiner, M.D., M.P.H., Zeynal Karaca, Ph.D., Brian J. Moore, Ph.D., Melina C. Imshaug, M.P.H., and Gary Pickens, Ph.D.
Introduction
Ambulatory surgery (AS), or outpatient surgery, is a planned operation for which the patient is not expected to be admitted to the hospital. Comparison of ambulatory surgery with inpatient surgery is essential for understanding utilization patterns for specific surgical procedures, including changing trends and estimates of total surgical volumes. As the number of surgical procedures capable of being safely performed in an ambulatory setting increases, comparisons of ambulatory surgery with inpatient surgery can also be useful in the evaluation of post-surgical complications, hospital cost savings, and patient experience of care surveys.
Self-reported facility estimates from the American Hospital Association suggest that a growing share of all surgeries at community hospitals in the United States are performed in the AS setting (66 percent in 2014, up from 57 percent in 1994),1 although an ambiguous definition for AS introduces variation across facility volume estimates. Recent reports on specific surgical procedure trends in a subset of States also point to a shift from the inpatient surgical setting to the AS setting.2,3 Nationally representative AS estimates for a broad group of surgical procedures do not yet exist.
This Healthcare Cost and Utilization Project (HCUP) Statistical Brief presents national data on surgeries performed in two hospital settings: hospital inpatient and hospital-based AS settings. The findings in this Statistical Brief represent an update and expansion of 2012 statistics previously reported.4 Procedures performed in freestanding (non-hospital-owned) AS centers were not included because many State AS data sources do not include these types of centers.
The analysis was limited to visits for an invasive surgery commonly performed for therapeutic purposes (i.e., to treat disease or injury); excluded were noninvasive surgeries and surgeries typically used for diagnostic or exploratory purposes (e.g., colonoscopy). The HCUP Surgery Flag Software for the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)5 and the HCUP Surgery Flag Software for Services and Procedures6 were used to identify invasive, therapeutic surgeries based on a narrow and targeted definition.7
This report presents characteristics of outpatient surgery visits and hospital inpatient stays for invasive, therapeutic surgical procedures. All references to surgeries, outpatient surgeries, or ambulatory surgeries refer to this subset of surgeries. We also present the distribution of outpatient surgeries compared with inpatient surgical procedures by payer, body system, and the most common surgical procedures performed in an outpatient setting overall and by payer. In addition, ambulatory and inpatient volume and procedure rates are compared for each procedure. Unless otherwise noted, volumes and rates are based on all-listed procedure codes.
Highlights |
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Table 1. Characteristics of hospital visits or stays for invasive, therapeutic surgery performed in hospital-based ambulatory and inpatient settings, 2014
CharacteristicAmbulatory settingInpatient settingTotal visits or stays for surgeries
Total number, N
9,915,100
7,247,600
Percent of total visits or stays for surgeries, %
57.8
42.2
Total surgeries
Total number, N
11,474,800
10,303,000
Percent of total surgeries, %
52.7
47.3
Number of surgeries per visit or stay, mean
1.2
1.4
Length of stay, mean, days
0.2
6.0
Visits or stays by type of community hospital, %
By hospital bed size
Large
53.9
58.3
Medium
26.1
26.3
Small
20.0
15.4
By hospital location, teaching status
Rural
14.6
6.6
Urban nonteaching
27.7
24.6
Urban teaching
57.7
68.8
By control/ownership of hospital
Non-Federal government
12.2
11.5
Private not-for-profit
76.9
73.7
Private for-profit
8.3
14.7
Note: Only invasive, therapeutic surgeries that are performed and reliably reported in the hospital-based ambulatory surgery setting were included.
Source: Agency for Healthcare Research and Quality (AHRQ), Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project (HCUP), National Inpatient Sample (NIS) and nationwide ambulatory surgery analytic file created from the State Ambulatory Surgery and Services Databases
(SASD), weighted for national estimates, 2014
Table 2. The 25 most common ambulatory invasive, therapeutic surgeries performed in community hospitals in the United States, 2014
All-listed CCS proceduresAll AS, %Surgeries, NaSurgeries, N per 100,000 populationbSurgeries performed in ambulatory setting, %ASInpatientASInpatientLens and cataract procedures
12.4
1,419,100
1,000
447.4
0.3
99.9
Muscle, tendon, and soft tissue OR procedures
6.6
755,500
295,300
238.2
93.1
71.9
Incision or fusion of joint, destruction of joint lesion
5.3
608,700
147,800
191.9
46.6
80.5
Cholecystectomy and common duct exploration
5.0
577,400
372,600
182.0
117.5
60.8
Excision of semilunar cartilage of knee
4.5
513,600
6,900
161.9
2.2
98.7
Inguinal and femoral hernia repair
3.8
435,900
38,300
137.4
12.1
91.9
Repair of diaphragmatic, incisional, and umbilical hernia
3.3
376,400
239,000
118.7
75.3
61.2
Tonsillectomy and/or adenoidectomy
3.1
356,100
16,800
112.3
5.3
95.5
Decompression peripheral nerve
2.8
322,500
16,300
101.7
5.1
95.2
OR procedures of skin and breast, including plastic procedures on breast
2.8
325,500
88,100
102.6
27.8
78.7
Myringotomy
2.6
298,600
8,300
94.1
2.6
97.3
Lumpectomy, quadrantectomy of breast
2.6
296,500
8,000
93.5
2.5
97.4
Insertion, revision, replacement, removal of cardiac pacemaker or cardioverter/defibrillator
2.5
286,400
245,600
90.3
77.4
53.8
Non-fracture, non-arthroplasty OR procedures on the bone
2.4
279,800
139,800
88.2
44.1
66.7
Hysterectomy, abdominal and vaginal
2.4
276,100
237,500
87.0
74.9
53.8
Partial excision bone
2.2
251,500
358,900
79.3
113.2
41.2
Laminectomy, excision intervertebral disc
1.9
219,900
438,300
69.3
138.2
33.4
Appendectomy
1.8
208,800
238,800
65.8
75.3
46.6
Vascular stents and OR procedures, other than head or neck
1.8
206,200
1,000,500
65.0
315.4
17.1
Testicular, prostate, and penile OR procedures
1.6
187,300
22,100
59.1
7.0
89.4
Vaginal, vulvar, and female pelvic OR procedures
1.6
187,600
74,500
59.1
23.5
71.6
Bunionectomy or repair of toe deformities
1.6
185,800
2,900
58.6
0.9
98.5
OR procedures of mouth, nose, and throat, excluding tonsils and teeth
1.5
175,100
76,400
55.2
24.1
69.6
Plastic procedures on nose
1.4
164,900
14,600
52.0
4.6
91.9
Lymph node biopsies and excisions, bone marrow procedures
1.3
152,200
301,100
48.0
94.9
33.6
Abbreviations: AS, ambulatory surgery; CCS, Clinical Classifications Software; OR, operating room
Notes: Only invasive, therapeutic surgeries that are performed and reliably reported in the hospital-based ambulatory surgery setting were included. Procedures are based on the Clinical Classifications Software (CCS) and Clinical Classifications Software for Services and Procedures. For more information on the CCS categories, please see the
Appendix.
a The number of discharges was rounded to the nearest 100.
b Based on population estimates from the U.S. Census Bureau
Source: Agency for Healthcare Research and Quality (AHRQ), Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project (HCUP), National Inpatient Sample (NIS) and nationwide ambulatory surgery analytic file created from the State Ambulatory Surgery and Services Databases (SASD), weighted for national
estimates, 2014
Table 3. The five most common ambulatory invasive, therapeutic surgeries performed in community hospitals in the United States by payer, 2014
All-listed CCS proceduresSurgeries, NaSurgeries performed in ambulatory setting, %ASInpatientMedicare
Lens and cataract procedures
985,000
400
100.0
Insertion, revision, replacement, removal of cardiac pacemaker or cardioverter/defibrillator
210,800
178,400
54.2
Muscle, tendon, and soft tissue OR procedures
186,600
119,600
60.9
Vascular stents and OR procedures, other than head or neck
136,700
551,800
19.9
Inguinal and femoral hernia repair
131,600
19,600
87.0
Medicaid
Tonsillectomy and/or adenoidectomy
140,400
7,400
95.0
Myringotomy
124,800
3,600
97.2
Cholecystectomy and common duct exploration
108,100
68,600
61.2
Muscle, tendon, and soft tissue OR procedures
83,200
48,600
63.1
Lens and cataract procedures
76,400
300
99.6
Private Insurance
Muscle, tendon, and soft tissue OR procedures
404,900
91,500
81.6
Incision or fusion of joint, destruction of joint lesion
361,600
51,900
87.4
Cholecystectomy and common duct exploration
328,900
133,900
71.1
Excision of semilunar cartilage of knee
328,100
2,900
99.1
Lens and cataract procedures
318,400
200
99.9
Uninsured
OR procedures of skin and breast, including plastic procedures on breast
45,400
4,800
90.4
Cholecystectomy and common duct exploration
15,700
31,500
33.3
Appendectomy
13,800
21,100
39.5
Lens and cataract procedures
13,700
100
99.3
Muscle, tendon, and soft tissue OR procedures
10,700
18,100
37.2
Abbreviation: AS, ambulatory surgery; CCS, Clinical Classifications Software; OR, operating room
Notes: Only invasive, therapeutic surgeries that are performed and reliably reported in the hospital-based ambulatory surgery setting were included. Procedures are based on the Clinical Classifications Software (CCS) and Clinical Classifications Software for Services and Procedures. For more information on the CCS categories, please see the Appendix.
a The number of discharges was rounded to the nearest 100.
Source: Agency for Healthcare Research and Quality (AHRQ), Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project (HCUP), National Inpatient Sample (NIS) and nationwide ambulatory surgery analytic file created from the State Ambulatory Surgery and Services Databases (SASD), weighted for national estimates, 2014
Appendix. Invasive, therapeutic surgeries, listed by body system, performed in community hospitals in the United States by setting (ambulatory versus inpatient), 2014
All-listed procedures (CCS number and description)Surgeries, NaSurgeries, N per 100,000 populationbSurgeries performed in ambulatory setting, %ASInpatientASInpatientOperations on the nervous
system
3: Laminectomy, excision intervertebral disc
219,900
438,300
69.3
138.2
33.4
6: Decompression peripheral nerve
322,500
16,300
101.7
5.1
95.2
9: Other OR therapeutic nervous system procedures
81,800
191,100
25.8
60.3
30.0
Operations on the endocrine system
10: Thyroidectomy, partial or complete
101,600
29,700
32.0
9.4
77.4
12: Other therapeutic endocrine procedures
39,400
38,500
12.4
12.1
50.6
Operations on the eye
13: Corneal transplant
30,100
300
9.5
0.1
99.0
15: Lens and cataract procedures
1,419,100
1,000
447.4
0.3
99.9
16: Repair of retinal tear, detachment
109,600
1,000
34.5
0.3
99.1
21: Other extraocular muscle and orbit therapeutic procedures
70,500
6,200
22.2
1.9
91.9
Operations on the ear
22: Tympanoplasty
26,500
700
8.3
0.2
97.4
23: Myringotomy
298,600
8,300
94.1
2.6
97.3
24: Mastoidectomy
17,100
2,500
5.4
0.8
87.2
26: Other therapeutic ear procedures
29,800
15,600
9.4
4.9
65.6
Operations on the nose, mouth, and pharynx
28: Plastic procedures on nose
164,900
14,600
52.0
4.6
91.9
30: Tonsillectomy and/or adenoidectomy
356,100
16,800
112.3
5.3
95.5
33: Other OR therapeutic procedures on nose, mouth and pharynx (OR procedures of mouth, nose, and throat, excluding tonsils and teeth)
175,100
76,400
55.2
24.1
69.6
Operations on the respiratory system
42: Other OR therapeutic procedures on respiratory system and mediastinum
39,100
104,300
12.3
32.9
27.3
Operations on the cardiovascular system
48: Insertion, revision, replacement, removal of cardiac pacemaker or cardioverter/defibrillator
286,400
245,600
90.3
77.4
53.8
53: Varicose vein stripping, lower limb
29,700
500
9.4
0.1
98.3
57: Creation, revision and removal of arteriovenous fistula or vessel-to-vessel cannula for dialysis
150,400
38,400
48.4
12.1
80.0
61: Other OR procedures on vessels other than head and neck (vascular stents and OR procedures, other than head or neck)
206,200
1,000,500
65.0
315.4
17.1
63: Other non-OR therapeutic cardiovascular procedures
33,700
689,600
10.6
217.4
4.7
Operations on the hemic and lymphatic system
67: Other therapeutic procedures, hemic and lymphatic system (lymph node biopsies and excisions, bone marrow procedures)
152,200
301,100
48.0
94.9
33.6
Operations on the digestive system
78: Colorectal resection
7,500
302,500
2.4
95.4
2.4
80: Appendectomy
208,800
238,800
65.8
75.3
46.6
84: Cholecystectomy and common duct exploration
577,400
372,600
182.0
117.5
60.8
85: Inguinal and femoral hernia repair
435,900
38,300
137.4
12.1
91.9
86: Other hernia repair (repair of diaphragmatic, incisional, and umbilical hernia)
376,400
239,000
118.7
75.3
61.2
87: Laparoscopy (GI only)
114,900
57,700
36.2
18.2
66.6
94: Other OR upper GI therapeutic procedures
7,700
159,100
2.4
50.2
4.6
96: Other OR lower GI therapeutic procedures
53,200
266,500
16.8
84.0
16.6
99: Other OR gastrointestinal therapeutic procedures
34,400
230,300
10.8
72.6
13.0
244: Gastric bypass and volume reductionc
31,400
0
9.9
0.0
100.0
Operations on the urinary system
100: Endoscopy and endoscopic biopsy of the urinary tract
16,400
161,100
5.2
50.8
9.2
101: Transurethral excision, drainage, or removal urinary obstruction
4,600
104,300
1.4
32.9
4.2
106: Genitourinary incontinence procedures
88,800
24,100
28.0
7.6
78.7
109: Procedures on the urethra
23,900
28,800
7.5
9.1
45.4
112: Other OR therapeutic procedures of urinary tract
28,100
87,100
8.8
27.4
24.4
Operations on the male genital system
113: Transurethral resection of prostate (TURP)
56,400
29,100
17.8
9.2
66.0
114: Open prostatectomy
3,400
61,600
1.1
19.4
5.2
118: Other OR therapeutic procedures, male genital (testicular, prostate, and penile OR procedures)
187,300
22,100
59.1
7.0
89.4
Operations on the female genital system
119: Oophorectomy, unilateral and bilateral
99,800
182,400
31.5
57.5
35.4
121: Ligation or occlusion of fallopian tubes
103,600
254,500
32.7
80.2
28.9
124: Hysterectomy, abdominal and vaginal
276,100
237,500
87.0
74.9
53.8
125: Other excision of cervix and uterus
16,000
38,100
5.1
12.0
29.6
129: Repair of cystocele and rectocele, obliteration of vaginal vault
68,300
30,000
21.5
9.5
69.5
132: Other OR therapeutic procedures, female organs (vaginal, vulvar, and female pelvic OR procedures)
187,600
74,500
59.1
23.5
71.6
Operations on the musculoskeletal system
142: Partial excision bone
251,500
358,900
79.3
113.2
41.2
143: Bunionectomy or repair of toe deformities
185,800
2,900
58.6
0.9
98.5
144: Treatment, facial fracture or dislocation
53,400
27,200
16.8
8.6
66.3
145: Treatment, fracture or dislocation of radius and ulna
117,800
60,100
37.2
19.0
66.2
147: Treatment, fracture or dislocation of lower extremity (other than hip or femur)
142,000
196,600
44.8
62.0
41.9
148: Other fracture and dislocation procedure
109,300
167,600
34.5
52.9
39.5
149: Arthroscopy
98,700
9,600
31.1
3.0
91.1
150: Division of joint capsule, ligament or cartilage
69,200
14,300
21.8
4.5
82.9
151: Excision of semilunar cartilage of knee
513,600
6,900
161.9
2.2
98.7
152: Arthroplasty knee
37,300
753,000
11.8
237.4
4.7
153: Hip replacement, total and partial
21,200
523,100
6.7
164.9
3.9
154: Arthroplasty other than hip or knee
49,900
104,500
15.7
33.0
32.3
157: Amputation of lower extremity
34,500
146,600
10.9
46.2
19.1
158: Spinal fusion
38,000
463,800
12.0
146.2
7.6
160: Other therapeutic procedures on muscles and tendons (muscle, tendon, and soft tissue OR procedures)
755,500
295,300
238.2
93.1
71.9
161: Other OR therapeutic procedures on bone (non-fracture, non-arthroplasty OR procedures on the bone)
279,800
139,800
88.2
44.1
66.7
162: Other OR therapeutic procedures on joints (incision or fusion of joint, destruction of joint lesion)
608,700
147,800
191.9
46.6
80.5
164: Other OR therapeutic procedures on musculoskeletal system
36,700
45,700
11.6
14.4
44.5
Operations on the integumentary (skin) system
166: Lumpectomy, quadrantectomy of breast
296,500
8,000
93.5
2.5
97.4
167: Mastectomy
61,200
42,600
19.3
13.4
59.0
174: Other non-OR therapeutic procedures on skin and breast
17,600
223,400
5.5
70.4
7.3
175: Other OR therapeutic procedures on skin and breast (OR procedures of skin and breast, including plastic procedures on breast)
325,500
88,100
102.6
27.8
78.7
Abbreviations: AS, ambulatory surgery; CCS, Clinical Classifications Software; OR, operating room; GI, gastrointestinal
Notes: Only invasive, therapeutic surgeries that are performed and reliably reported in the hospital-based ambulatory surgery setting were included. Procedures are based on the Clinical Classifications Software (CCS) and the CCS for Services and Procedures. Statistics are based on the "narrow" definition of the HCUP Surgery Flag
software.
a The number of discharges was rounded to the nearest 100.
b Based on population estimates from the U.S. Census Bureau
c The gastric bypass and volume reduction CCS category (244) does not exist in the ICD-9-CM categorization. Inpatient gastric bypass and volume reductions are included in alternative categories, such as CCS 94, Other upper GI Therapeutic procedures.
Source: Agency for Healthcare Research and Quality (AHRQ), Center for
Delivery, Organization, and Markets, Healthcare Cost and Utilization Project (HCUP), National Inpatient Sample (NIS) and nationwide ambulatory surgery analytic file created from the State Ambulatory Surgery and Services Databases (SASD), weighted for national estimates, 2014
Data Source
The estimates in this Statistical Brief are based upon data from the Healthcare Cost and Utilization Project (HCUP) 2014 National Inpatient Sample (NIS) and 2014 nationwide ambulatory surgery analytic file created from the State Ambulatory Surgery and Services Databases (SASD), weighted for national estimates. This report evaluates both inpatient and outpatient surgery data. SASD from 22 States were used to create the nationwide ambulatory surgery analytic file: California, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Minnesota, Missouri, Nebraska, Nevada, New Jersey, New York, North Carolina, North Dakota, Oklahoma, Oregon, Pennsylvania, South Dakota, and Texas. The ambulatory surgery analytic file included 2.0 million unweighted discharges.
The study population in the ambulatory surgery analytic file includes discharges with invasive, therapeutic surgeries from community, nonrehabilitation hospitals with a service type of either general acute care or children's hospital. Weights for national estimates were developed using stratification on hospital characteristics (census region, bed size, location/teaching status, ownership). Supplemental sources included population denominator data for use with HCUP databases, derived from information available from the Bureau of the Census.8
Definitions
Procedures, ICD-9-CM, Current Procedural Terminology (CPT®), 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. The first-listed procedure is the procedure that is listed first on the discharge record. Inpatient data define this as the principal procedure—the procedure that is performed for definitive
treatment rather than for diagnostic or exploratory purposes (i.e., the procedure that was necessary to take care of a complication).
Procedures on inpatient hospitalization records are coded using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM); procedures on ambulatory surgery and services records can be coded using either ICD-9-CM or the CPT.
ICD-9-CM and CPT both assign numeric codes to procedures; ICD-9-CM is limited to procedures in the inpatient setting. There are approximately 4,000 ICD-9-CM procedure codes and 9,600 CPT procedure codes.
CCS categorizes ICD-9-CM procedure codes into a manageable number of clinically meaningful categories.9 This clinical grouper makes it easier to quickly understand patterns of procedure use. When CPT was used on ambulatory surgery records, the CCS for Services and Procedures10 was used to classify procedures into groupings comparable to the CCS.
Case definition
For this report, the case definition was based on criteria developed with 2012 ambulatory surgery data and validated against other datasets. To facilitate comparisons across years, the same CCS procedure categories that were selected for inclusion in 2012 were used to create a 2014 nationwide ambulatory surgery analytic file. For this report, records from the SASD meeting the following criteria were included in the nationwide ambulatory surgery analytic file:
- The HCUP Surgery Flag Software for Services and Procedures11 was used to identify procedures that are classified as a surgery based on a narrow definition (surgery flag value = NARROW). Records with one or more narrow surgery procedures were retained. All procedures that did not meet the narrow surgery definition were dropped from the record.
- A CCS procedure category was included if—
- The total SASD procedure count across all available States in the CCS category was greater than 4,000
- At least 25 percent of outpatient procedures in the CCS category were performed in the hospital outpatient setting (as opposed to ambulatory surgery centers, office, and other outpatient settings)
- There was no evidence of substantial underreporting by hospitals (CCS categories for dental services, wound debridement, and skin graft were excluded based on this criteria)
- A SASD facility was included if—
- It was identified as a community, nonrehabilitation hospital with a service type of either general acute care or children's hospital
- The ratio of SASD surgery visits for Medicare fee-for-service patients to Medicare Standard Analytic File surgeries for the facility was within the range of [0.8, 1.2]
- The facility provided CPT codes for the preponderance of outpatient surgery visits
- The facility had at least 100 ambulatory surgery visits in 2014
For this report, records from the NIS meeting the following criteria were included:
- The HCUP Surgery Flag Software for ICD-9-CM12 was used to identify procedures that are classified as a surgery based on a narrow definition (surgery flag value = NARROW). Records with one or more narrow surgery procedures were retained. All procedures that did not meet the narrow surgery definition were dropped from the record.
- A CCS procedure category was included if it met the above definition for inclusion of ambulatory surgery procedures.
Therefore, the implied hierarchy of surgeries can be considered as follows:
- All surgeries
- Narrow surgeries
- Selected narrow surgeries (based on the above criteria)
- Outpatient surgeries
- Outpatient surgeries in hospitals or hospital-owned AS facilities
- Outpatient surgeries
- Selected narrow surgeries (based on the above criteria)
- Narrow surgeries
Types of hospitals included in the HCUP National Inpatient Sample
The National
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 a psychiatric or chemical dependency condition in a community hospital, the discharge record for that stay will be included in the NIS.
Types of hospitals included in HCUP State Ambulatory Surgery and Services Databases
This analysis used State Ambulatory Surgery and Services Databases (SASD) limited to data from hospital-owned ambulatory surgery facilities.
Although some SASD include data from facilities not owned by a hospital, those facilities were excluded from this analysis. The designation of a facility as hospital-owned is specific to its financial relationship with a hospital that provides inpatient care and is not related to its physical location. Ambulatory surgery performed in hospital-owned facilities may be performed within the hospital, in a facility attached to the hospital, or in a facility physically separated from the hospital. The
analysis was further limited to ambulatory surgeries performed at facilities owned by community hospitals. Community hospitals are defined as short-term, non-Federal, general, and other specialty hospitals, excluding hospital units of other institutions (e.g., prisons). We limited the analysis to community hospitals with at least 100 ambulatory surgery visits per year.
Unit of analysis
The unit of analysis is the ambulatory surgery visit or 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.
Hospital location
The classification of whether a hospital is in a metropolitan area (urban) or nonmetropolitan area (rural) is defined from the American Hospital Association (AHA) Annual Survey, using the 1993 U.S. Office of Management and Budget definition.
Payer
Payer is the expected 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' 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.
For this Statistical Brief, when more than one payer is listed for a hospital discharge, the first-listed payer is used.
About HCUP
The Healthcare Cost and Utilization Project (HCUP, pronounced "H-Cup") is a family of healthcare databases and related software tools and products developed through a Federal-State-Industry partnership and sponsored by the Agency for Healthcare Research and Quality (AHRQ). HCUP databases bring together the data collection efforts of State data organizations, hospital associations, and private data organizations (HCUP Partners) and the Federal government to create a national information resource of encounter-level healthcare data. HCUP includes the largest collection of longitudinal hospital care data in the United States, with all-payer, encounter-level information beginning in 1988. These databases enable research on a broad range of health policy issues, including cost and quality of health services, medical practice patterns, access to healthcare programs, and outcomes of treatments at the national, State, and local market levels.
HCUP would not be possible without the contributions of the following data collection Partners from across the United States:
Alaska Department of Health and Social Services
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
District of Columbia 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
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 State Department of Health
Missouri Hospital Industry Data Institute
Montana Hospital Association
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 Office of Health Analytics
Pennsylvania Health Care Cost Containment Council
Rhode Island Department of Health
South Carolina Revenue and Fiscal Affairs Office
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 Statistical Briefs
HCUP Statistical Briefs are descriptive summary reports presenting statistics on hospital inpatient, ambulatory surgery, and emergency department use and costs, quality of care, access to care, medical conditions, procedures, patient populations, and other topics. The reports use HCUP administrative healthcare data.
About the NIS
The HCUP National Inpatient Sample (NIS) is a national database of hospital inpatient stays. The NIS is nationally representative of all community hospitals (i.e., short-term, non-Federal, nonrehabilitation hospitals). The NIS includes all payers. It is drawn from a sampling frame that contains hospitals comprising more than 95 percent of all discharges in the United States. The vast size of the NIS allows the study of topics at the national and regional levels for specific subgroups of patients. In addition, NIS data are standardized across years to facilitate ease of use. Over time, the sampling frame for the NIS has changed; thus, the number of States contributing to the NIS varies from year to year. The NIS is intended for national estimates only; no State-level estimates can be produced.
The 2012 NIS was redesigned to optimize national estimates. The redesign incorporates two critical changes:
- Revisions to the sample design—starting with 2012, the NIS is now a sample of discharge records from all HCUP-participating hospitals, rather than a sample of hospitals from which all discharges were retained (as is the case for NIS years before 2012).
- Revisions to how hospitals are defined—the NIS now uses the definition of hospitals and discharges supplied by the statewide data organizations that contribute to HCUP, rather than the definitions used by the American Hospital Association (AHA) Annual Survey of Hospitals.
The new sampling strategy is expected to result in more precise estimates than those that resulted from the previous NIS design by reducing sampling error: for many estimates, confidence intervals under the new design are about half the length of confidence intervals under the previous design. The change in sample design for 2012 necessitates recomputation of prior years NIS data to enable analysis of trends that uses the same definitions of discharges and hospitals.
About the SASD
The HCUP State Ambulatory Surgery and Services Databases (SASD) include encounter-level data for ambulatory surgeries and may also include various types of outpatient services such as observation stays, lithotripsy, radiation therapy, imaging, chemotherapy, and labor and delivery. The specific types of ambulatory surgery and outpatient services included in each SASD vary by State and data year. All SASD include data from hospital-owned ambulatory surgery facilities. In addition, some States include data from facilities not owned by a hospital. The designation of a facility as hospital-owned is specific to its financial relationship with a hospital that provides inpatient care and is not related to its physical location. Hospital-owned ambulatory surgery and other outpatient care facilities may be contained within the hospital, physically attached to the hospital, or located in a different geographic area. In order to provide information that is comparable across all States, analysis was restricted to hospital-owned ambulatory surgery.
For More Information
For other information on procedures and treatments, including procedures in the ambulatory surgery setting, refer to the HCUP Statistical Briefs located at www.hcup-us.ahrq.gov/reports/statbriefs/sb_procedures.jsp.
For additional HCUP statistics, visit:
- HCUP Fast Stats at //datatools.ahrq.gov/hcup-fast-stats for easy access to the latest HCUP-based statistics for health information topics
- HCUPnet, HCUPs interactive query system, at datatools.ahrq.gov/hcupnet
For more information about HCUP, visit www.hcup-us.ahrq.gov/.
For a detailed description of HCUP and more information on the design of the National (Nationwide) Inpatient Sample (NIS) and State Ambulatory Surgery and Services Databases (SASD), please refer to the following database documentation:
Agency for Healthcare Research and Quality. Overview of the National (Nationwide) Inpatient Sample (NIS). Healthcare Cost and Utilization Project (HCUP). Rockville, MD: Agency for Healthcare Research and Quality. Updated December 2016. www.hcup-us.ahrq.gov/nisoverview.jsp. Accessed January 31, 2017.
Agency for Healthcare Research and Quality. Overview of the State Ambulatory Surgery and Services Databases (SASD). Healthcare Cost and Utilization Project (HCUP). Rockville, MD: Agency for Healthcare Research and Quality. Updated June 2016. www.hcup-us.ahrq.gov/sasdoverview.jsp. Accessed January 31, 2017.
Suggested Citation
Steiner CA (Institute for Health Research, Kaiser Permanente), Karaca Z (AHRQ), Moore BJ (IBM Watson Health), Imshaug MC (IBM Watson Health), Pickens G (IBM Watson Health). Surgeries in Hospital-Based Ambulatory Surgery and Hospital Inpatient Settings, 2014. HCUP Statistical Brief #223. May 2017. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/reports/statbriefs/sb223-Ambulatory-Inpatient-Surgeries-2014.pdf.
Acknowledgments
The authors would like to acknowledge the contributions of Clare Sun of IBM Watson Health.
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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 or send a letter to the address below:
Sharon B. Arnold, Ph.D., Acting Director
Center for Delivery, Organization, and Markets
Agency for Healthcare Research and Quality
5600 Fishers Lane
Rockville, MD 20857
This Statistical Brief was posted online on May 11, 2017.
The revised version of this Statistical Brief was posted online on February 5,
2018.
A second revision of this Statistical Brief was posted online on July 20, 2020.
1 American Hospital Association. Utilization and Volume. In: Trends Affecting Hospitals and Health Systems. Updated for 2016; chapter 3. //www.aha.org/system/files/research/reports/tw/chartbook/2016/chapter3.pdf.
2 Moore BJ, Steiner CA, Davis PH, Stocks C, Barrett ML. Trends in Hysterectomies and Oophorectomies in Hospital Inpatient and Ambulatory Settings, 2005-2013. HCUP Statistical Brief #214. November 2016. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/reports/statbriefs/sb214-Hysterectomy-Oophorectomy-Trends.pdf. Accessed December 5, 2016.
3 Steiner CA, Weiss AJ, Barrett ML, Fingar KR, Davis PH. Trends in Bilateral and Unilateral Mastectomies in Hospital Inpatient and Ambulatory Settings, 2005-2013. HCUP Statistical Brief #201. February 2016. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/reports/statbriefs/sb201-Mastectomies-Inpatient-Outpatient.pdf. Accessed December 5, 2016.
4 Wier LM, Steiner CA, Owens PL. Surgeries in Hospital-Owned Outpatient Facilities, 2012. HCUP Statistical Brief #188. February 2015. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/reports/statbriefs/sb188-Surgeries-Hospital-Outpatient-Facilities-2012.pdf. Accessed December 2, 2016.
5 Agency for Healthcare Research and Quality. HCUP Surgery Flag Software for ICD-9-CM. Healthcare Cost and Utilization Project (HCUP). Rockville, MD: Agency for Healthcare Research and Quality. Updated February 26, 2016. www.hcup-us.ahrq.gov/toolssoftware/surgflags/surgeryflags.jsp. Accessed October 10, 2016.
6 Agency for Healthcare Research and Quality. HCUP Surgery Flag Software for Services and Procedures. Healthcare Cost and Utilization Project (HCUP). Rockville, MD: Agency for Healthcare Research and Quality. Updated August 2019. www.hcup-us.ahrq.gov/toolssoftware/surgeryflags_svcproc/surgeryflagssvc_proc.jsp. Accessed June 23, 2020.
7 The narrow surgery definition includes surgical procedures that involve incision, excision, manipulation, or suturing of tissue that penetrates or breaks the skin; typically require use of an operating room; and also require regional anesthesia, general anesthesia, or sedation to control pain. The version of the HCUP Surgery Flag Software for Services and Procedures used for this Statistical Brief did not include cardiac CPT codes.
8 Barrett M, McCarty J, Coffey R, Levit K. Population Denominator Data for Use with the HCUP Databases (Updated with 2015 Population Data). HCUP Methods Series Report #2016-04. September 29, 2016. U.S. Agency for Healthcare Research and Quality. www.hcup-us.ahrq.gov/reports/methods/2016-04.pdf. Accessed January 31, 2017.
9 Agency for Healthcare Research and Quality. HCUP Clinical Classifications Software (CCS) for ICD-9-CM. Healthcare Cost and Utilization Project (HCUP). Rockville, MD: Agency for Healthcare Research and Quality. Updated October 2016. www.hcup-us.ahrq.gov/toolssoftware/ccs/ccs.jsp. January 31, 2017.
10 Agency for Healthcare Research and Quality. HCUP Clinical Classifications Software for Services and Procedures. Healthcare Cost and Utilization Project (HCUP). Rockville, MD: Agency for Healthcare Research and Quality. Updated May 2014. www.hcup-us.ahrq.gov/toolssoftware/ccs_svcsproc/ccssvcproc.jsp. Accessed October 31, 2016.
11 Agency for Healthcare Research and Quality. HCUP Surgery Flag Software for Services and Procedures. Healthcare Cost and Utilization Project (HCUP). Rockville, MD: Agency for Healthcare Research and Quality. Updated August 2019. www.hcup-us.ahrq.gov/toolssoftware/surgeryflags_svcproc/surgeryflagssvc_proc.jsp. Accessed June 23, 2020.
12 Agency for Healthcare Research and Quality. HCUP Surgery Flag Software for ICD-9-CM. Healthcare Cost and Utilization Project (HCUP). Rockville, MD: Agency for Healthcare Research and Quality. Updated February 26, 2016. www.hcup-us.ahrq.gov/toolssoftware/surgflags/surgeryflags.jsp. Accessed October 10, 2016.