Characteristics of hospital stays involving operating room procedures, 2011

In 2011, a total of 38.6 million hospital stays occurred in the United States at an aggregate cost of $387.2 billion. Of these, just over one-fourth of the stays (28.9 percent) and nearly half of the costs (47.9 percent) involved hospitalizations during which OR procedures were performed (Figure 1).

Figure 1

Percentage of inpatient discharges and aggregate costs for hospital stays with and without operating room (OR) procedures in U.S. hospitals, 2011. Source: Agency for Healthcare Research and Quality (AHRQ), Center for Delivery, Organization, and Markets, (more...)

Table 1 presents the patient characteristics for hospital stays with and without OR procedures. The vast majority of these hospital stays occurred among adults aged 20–84 years (81.3% of stays involving OR procedures and 73.1% of stays without OR procedures). Children (aged 0–19 years) and the elderly (aged 85 years and older) were less likely to undergo OR procedures. Females accounted for just over half of hospital stays, with and without an OR procedure. Among hospital stays involving an OR procedure, the most common expected primary payers were private insurance (41.3 percent of stays) and Medicare (34.0 percent). For hospital stays that did not involve an OR procedure, Medicare was the most common primary payer (42.1 percent of stays).

Table 1

Patient characteristics for hospital stays with and without operating room (OR) procedures in U.S. hospitals, 2011.

Overall, hospital stays with OR procedures accounted for $185 billion and stays without OR procedures accounted for $202 billion (Table 2). Hospital stays with OR procedures were twice as expensive as hospital stays without OR procedures in total costs (mean cost of $16,700 versus $7,400 per stay) and cost per day ($3,300 versus $1,700).

Table 2

Resource use and outcomes for hospital stays with and without operating room (OR) procedures in U.S. hospitals, 2011.

Hospital stays involving an OR procedure were longer than stays that did not involve an OR procedure (5.0 versus 4.4 days). Elective hospital admission was more frequent for stays that involved an OR procedure (48.5 percent) than for stays without an OR procedure (13.4 percent).

Hospital stays with an OR procedure were less likely to involve major or extreme severity of illness compared with stays that did not involve an OR procedure (23.7 versus 34.7 percent of stays). Patients with an OR procedure were half as likely to die in the hospital compared with those who did not have an OR procedure (1.1 versus 2.2 percent).

Most frequent and costly types of operating room procedures, 2011

Table 3 provides the top 20 most frequent all-listed OR procedures. Together, these 20 procedures accounted for more than half (54.0 percent) of the 15.7 million OR procedures performed in 2011. Cesarean section and circumcision were the most common OR procedures, accounting for more than 8 percent and 7 percent of all OR procedures, respectively. Five musculoskeletal procedures—knee arthroplasty, laminectomy, spinal fusion, hip replacement, and treatment of hip or lower extremity fracture or dislocation—together accounted for about 17 percent of all OR procedures. Four cardiac procedures—percutaneous coronary angioplasty (PTCA), coronary artery bypass graft (CABG), cardiac device-related procedures, and heart valve procedures—together accounted for another 7 percent of all OR procedures.

Table 3

Most frequent all-listed operating room (OR) procedures performed in U.S. hospitals, 2011.

Table 4 lists the top 20 OR procedures with the highest aggregate hospital costs for the entire hospital stay during which this procedure was first listed on the discharge record. Together, these 20 procedures accounted for more than half (57.5 percent) of all costs associated with stays involving OR procedures and more than one-fourth (26.8 percent) of all hospital costs for stays of any type.

Table 4

Most costly first-listed operating room (OR) procedures performed in U.S. hospitals, 2011.

Six of the top 20 OR procedures with the highest aggregate hospital costs were musculoskeletal procedures: spinal fusion (7.1 percent of aggregate costs for stays with OR procedures), knee arthroplasty (6.3 percent), hip replacement (4.4 percent), treatment of hip fracture (2.4 percent), laminectomy (1.3 percent), and treatment of other lower extremity fracture (1.2 percent).

Four heart-related procedures were among the top 20 OR procedures with the highest aggregate costs: PTCA (5.4 percent of costs for stays with OR procedures), CABG (3.6 percent), heart valve procedures (3.4 percent), and pacemaker/cardioverter/defibrillator procedures (2.2 percent). Among the 20 OR procedures with the highest aggregate hospital costs, heart valve procedures and CABG had the highest mean costs per hospital stay ($53,400 and $38,700, respectively).

Two childbirth and delivery-related procedures (Cesarean section and circumcision) were also in the top 20 OR procedures with the highest aggregate costs, accounting for 4.1 percent and 1.0 percent of costs for stays with OR procedures.

Four gastrointestinal procedures were in the top 20: colorectal resection (3.7 percent of aggregate inpatient costs for stays with OR procedures), cholecystectomy (2.8 percent), appendectomy (1.4 percent), and small bowel resection (1.3 percent).

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

CCS categorizes procedure codes into clinically meaningful categories.⁸ 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. In addition, procedure categories that are nonspecific or likely to be adjuncts to other procedures (e.g., excision, lysis peritoneal adhesions; partial bone excision; intraoperative cholangiogram) are not included in the listings of specific procedures in Tables 3 and 4.

Major operating room (OR) procedures were defined using procedure classes, which categorize each ICD-9-CM procedure code as either major therapeutic, major diagnostic, minor therapeutic, or minor diagnostic.⁹ Major OR procedures are considered to be valid OR procedures based on diagnosis-related groups (DRGs). This classification scheme relies upon physician panels that classify ICD-9-CM procedure codes according to whether the procedure would be performed in a hospital operating room in most hospitals.

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. However, if a patient received long-term care, rehabilitation, or treatment for psychiatric or chemical dependency conditions in a community hospital, the discharge record for that stay will be included in the Nationwide Inpatient Sample (NIS).

Unit of analysis

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

Costs and charges

Total hospital charges were converted to costs using HCUP Cost-to-Charge Ratios based on hospital accounting reports from the Centers for Medicare & Medicaid Services (CMS).¹⁰ Costs will reflect the actual expenses incurred in the production of hospital services, such as wages, supplies, and utility costs; charges represent the amount a hospital billed for the case. For each hospital, a hospital-wide cost-to-charge ratio is used. Hospital charges reflect the amount the hospital billed for the entire hospital stay and do not include professional (physician) fees. For the purposes of this Statistical Brief, costs are reported to the nearest hundred.

Aggregate costs are calculated using aggregate charges. Aggregate charges include discharges with missing or invalid charges that are imputed by taking the mean charges for all discharges of the same diagnosis-related group (DRG) with nonmissing charges. Fewer than 2 percent of cases are missing charges in HCUP data. Mean costs are calculated using only discharges with nonmissing and valid charges. Because of the manner in which missing charges are imputed to calculate aggregate charges, simple calculation of the number of discharges multiplied by the mean cost will not always equal the aggregate costs.

Payer

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

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Medicare: includes patients covered by fee-for-service and managed care Medicare

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Medicaid: includes patients covered by fee-for-service and managed care Medicaid

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Private Insurance: includes Blue Cross, commercial carriers, and private health maintenance organizations (HMOs) and preferred provider organizations (PPOs)

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Other: includes Worker's Compensation, TRICARE/CHAMPUS, CHAMPVA, Title V, and other government programs

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Uninsured: includes an insurance status of “self-pay” and “no charge.”

Encounters 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 SCHIP patients specifically, it is not possible to present this information separately.

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

Patient complexity

Cases with the highest severity of illness are discharges with a score of 3 or 4 on the All Patient Refined DRG (APR-DRG) severity of illness scale. The four severity of illness subclasses are numbered sequentially from 1 to 4 indicating minor, moderate, major, or extreme severity of illness. The determination of severity of illness is disease specific. Thus, the significance attributed to complicating or comorbid conditions is dependent on the underlying problem. For example, certain types of infections are considered a more significant problem in a patient who is immunosuppressed than in a patient with a fractured arm. In APR-DRGs, high severity of illness is primarily determined by the interaction of multiple diseases. Patients with multiple comorbid conditions involving multiple organ systems represent difficult-to-treat patients who tend to have poor outcomes. The assignment of a patient to a severity of illness subclass takes into consideration not only the level of the secondary diagnoses but also the interaction among secondary diagnoses, age, principal diagnosis, and the presence of certain operating room and nonoperating room procedures.