Overview of ED visits related to bicycle injury

In 2009, there were 418,700 emergency department visits for injuries related to bicycle accidents in the U.S. In more than 1 in 10 of these visits (12 percent or 50,600 visits), a motor vehicle was also involved in the accident which caused the injury (table 1). Bicycle-related ED visits involving motor vehicles occurred at a rate of 16.5 visits per 100,000 population, while those not involving motor vehicles occurred at a rate of 119.9 visits per 100,000 population.

Table 1

Characteristics of bicycle injuries treated in emergency departments, 2009.

The majority of bicycle-related ED visits were treated and released from the ED (82.4 percent of those involving motor vehicles, 92.9 percent of those not involving motor vehicles). Hospital admissions more frequently resulted from those injuries in which a motor vehicle was involved in the accident (16.3 percent were admitted) than from those in which there was no motor vehicle involvement (6.7 percent).

ED visits for injuries related to bicycle accidents were much more likely to occur among males than females; the magnitude of the gender difference was much greater than for all injury-related ED visits. Visits for bicycle-related injuries without motor vehicle involvement were 2.7 times more common among males than females (176.3 visits per 100,000 population versus 64.7 visits per 100,000 population); visits for bicycle-related injuries involving a motor vehicle were 4.5 more common among males than females (27.2 visits per 100,000 population versus 6.1 visits per 100,000 population).

Bicycle-related ED visits involving motor vehicles occurred twice as often among persons living in urban areas as they did among those living in rural areas (17.7 visits per 100,000 population versus 8.9 visits per 100,000 population). ED visits for bicycle-related injuries without motor vehicle involvement were slightly more likely to occur among those living in rural areas than in other areas (127.3 visits per population versus 117.1 visits per population).

ED visits for injuries related to bicycle accidents involving motor vehicles also occurred more frequently among those living in low income communities than among those living in other communities (19.7 visits per population versus 14.8 visits per population). There was no significant difference by income in the rates of bicycle accidents without motor vehicle involvement.

Private insurance was the most common expected primary payer for both types of bicycle-related ED visits, covering 42.7 percent of those involving motor vehicles and 48.4 percent of those without motor vehicle involvement. Almost one-third of bicycle-related ED visits for accidents involving motor vehicles were uninsured (29.0 percent); Medicaid was the expected payer for 17.4 percent. In contrast, Medicaid covered almost one-quarter of those accidents without motor vehicle involvement (26.5 percent), and only 16.3 percent were uninsured.

Overview of hospital stays related to bicycle injury

There were 27,900 inpatient community hospital stays for injuries related to bicycle accidents in 2009; in 26 percent of these, a motor vehicle was involved in the accident which caused the injury (table 2). Bicycle-related inpatient stays involving motor vehicles occurred at a rate of 2.4 visits per 100,000 population, while those not involving motor vehicles occurred at a rate of 6.7 visits per 100,000 population.

Table 2

Characteristics of bicycle-related hospital inpatient stays, 2009.

Stays for a bicycle-related injury involving a motor vehicle were longer and more expensive than for bicycle injuries with no motor vehicle involvement (6.3 days versus 3.6 days, $18,900 cost per stay versus $10,600 cost per stay). Patients whose bicycle injuries involved a motor vehicle were more likely to die in the hospital than were patients whose bicycle injuries did not involve a motor vehicle (3.1 percent versus 0.5 percent).

Inpatient stays for injuries related to bicycle accidents were much more likely to occur among males than females. Stays for bicycle-related injuries without motor vehicle involvement were 3.5 times more common among males than females (10.3 stays per 100,000 population versus 3.0 stays per 100,000 populations); visits for bicycle-related injuries involving a motor vehicle were 5.1 more common among males than females (3.9 stays per 100,000 population versus 0.8 stays per 100,000 population).

Hospital stays for bicycle-related injuries involving motor vehicles occurred over twice as often among persons living in urban areas as they did among those living in rural areas (2.6 stays per 100,000 population versus 0.9 stays per 100,000 population). Stays for bicycle-related injuries without motor vehicle involvement were also more likely to occur among those living in urban areas than in rural areas (7.0 stays per population versus 4.3 stays per 100,000 population) despite the similar rate of ED visits for these accidents in both areas (table 1).

Injuries related to bicycle accidents involving motor vehicles resulted in similar rates of hospital stays among those living in low income and other communities. Injuries related to bicycle accidents without motor vehicle involvement more frequently resulted in hospital stays among those living in higher income communities than lower income (6.8 stays per 100,000 population versus 5.5 stays per 100,000 population).

Private insurance was the most common expected primary payer for both types of bicycle-related ED stays, covering 51.9 percent of those involving motor vehicles and 50.7 percent of those without motor vehicle involvement. Almost one-fifth of bicycle-related hospital stays for accidents involving motor vehicles were uninsured (19.0 percent); Medicaid was the expected payer for 18.3 percent. Medicaid covered 15.2 percent of those accidents without motor vehicle involvement, and only 14.4 percent were uninsured (table 2).

Rates of bicycle-related hospitalizations and ED visits, 2009

ED visits for bicycle-related injuries in which a motor vehicle was also involved in the accident were most common among individuals 10–14 years old (32 visits per 100,000 per population) and 15–19 years old (35 visits per 100,000 per population) (figure 1). Among adults, individuals 20–29 years old were most likely to be hospitalized for a bicycle-related injury involving a motor vehicle, followed by individuals 40–49 years old.

Figure 1

Rates of ED visits for bicycle-related injuries by age and motor-vehicle involvement, 2009. Source: AHRQ, Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project, Nationwide Emergency Department Sample, 2009

ED visits for bicycle-related injuries without motor vehicle involvement were more common among children and adolescents than adults. There were 410 visits per 100,000 population for individuals 10–14 years old, with the rate of injuries peaking in this age group and then generally decreasing with age. Adults age 50 and older had 52 visits per 100,000 per population.

Most common injuries associated with bicycle-related ED visits and hospitalizations, 2009

Contusion was the most common first-listed diagnosis among ED visits for bicycle-related injuries, accounting for over one-quarter of such visits (table 3). Fractures, open wounds, sprains and strains, intracranial injury and joint disorders and dislocations were also among the 10 most common first-listed diagnoses for ED visits related to bicycle injuries.

Table 3

Ten most common injuries in bicycle injury related ED visits, 2009.

Intracranial injury, the sixth most common first-listed diagnosis among bicycle-related injury ED visits, was the most common principal diagnosis among hospital stays for bicycle-related injury (5,800 inpatient stays, or 21 percent of hospital stays for bicycle-related injury) (table 4). Fractures accounted for over 40 percent of such stays and included fractures of lower limbs, upper limbs, hip, skull and face and other fractures.

Table 4

Ten most common injuries in bicycle injury related hospital inpatient stays, 2009.

Most common procedures associated bicycle-related hospitalizations, 2009

Approximately one-third of bicycle-related hospital stays involved a procedure for treatment of a fracture. Other procedures commonly performed on patients hospitalized for a bicycle-related injury included sutures, chest drainage, respiratory intubation and mechanical ventilation and hip replacement (table 5).

Table 5

Stays for top ten principal procedures for bicycle injury related hospital inpatient stays, 2009.

Diagnoses, ICD-9-CM, E-codes, and Clinical Classifications Software (CCS)

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

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

The External Cause of Injury Codes (commonly referred to as E-codes) supplement the ICD-9-CM diagnosis codes. These codes designate the cause of injury. Multiple E-codes may be present on a single hospital record.

CCS categorizes ICD-9-CM diagnoses into a manageable number of clinically meaningful categories.⁷ This “clinical grouper” makes it easier to quickly understand patterns of diagnoses. CCS categories identified as “Other” are typically not reported; these categories include miscellaneous, otherwise unclassifiable diagnoses that may be difficult to interpret as a group.

Procedures, ICD-9-CM, and Clinical Classifications Software (CCS)

The principal procedure is the procedure that is performed for definitive treatment rather than performed for diagnostic or exploratory purposes (i.e., the procedure that was necessary to take care of a complication). If two procedures appear to meet this definition, the procedure most related to the principal diagnosis is selected as the principal procedure.

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” are typically not reported; these categories include miscellaneous, otherwise unclassifiable procedures that may be difficult to interpret as a group.

Case definition

The ICD-9-CM codes defining bicycle-related injuries in which a motor vehicle was involved include diagnosis codes in the following range: E810.6, E811.6, E812.6, E813.6, E814.6, E815.6, E816.6, E817.6, E818.6, E819.6. The ICD-9-CM codes defining bicycle-related injuries with no motor vehicle involvement include diagnosis codes in the following range: E800.3, E801.3, E802.3, E803.3, E804.3, E805.3, E806.3, E807.3; E820.6, E821.6, E822.6, E823.6, E824.6, E825.6; E826.1, E826.9, E827.1, E828.1, E829.1.

Types of hospitals included in HCUP

HCUP is based on data from community hospitals, 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 NIS.

Unit of analysis

The unit of analysis is the hospital discharge (i.e., the hospital stay) or emergency department visit, 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).⁹ 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.

Mean cost per day is calculated as the mean cost per stay divided by the mean length of stay.

Location of patients’ residence

Place of residence is based on the urban-rural classification scheme for U.S. counties developed by the National Center for Health Statistics (NCHS). For this Statistical Brief, we collapsed the NCHS categories into either urban or rural according to the following:

Urban:

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Large Central Metropolitan: includes metropolitan areas with 1 million or more residents

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Large Fringe Metropolitan: includes counties of metropolitan areas with 1 million or more residents

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Medium and Small Metropolitan: includes areas with 50,000 to 999,999 residents.

Rural:

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Micropolitan and Noncore: includes nonmetropolitan counties (i.e., counties with no town greater than 50,000 residents).

Median community-level income

Median community-level income is the median household income of the patient’s ZIP Code of residence. The cut-offs for the quartile designation are determined using ZIP Code demographic data obtained from Claritas. The income quartile is missing for homeless and foreign patients.

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 more general groups:

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

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Medicaid: includes fee-for-service and managed care Medicaid patients. 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.

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Private Insurance: includes Blue Cross, commercial carriers, and private HMOs and 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.”

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

Discharge status

Discharge status indicates the disposition of the patient at discharge from the hospital and includes the following six categories: routine (to home); transfer to another short-term hospital; other transfers (including skilled nursing facility, intermediate care, and another type of facility such as a nursing home); home health care; against medical advice (AMA); or died in the hospital.