ED visits for headache as a first-listed diagnosis

During 2008, there were 8,246 ED visits per day specifically for headache as the first-listed diagnosis. This equates to 989 ED visits per 100,000 U.S. population (table 2).

Table 2

Characteristics of headache-related ED visits, 2008.

The rate of ED visits for females was 2.7 times higher than the rate for males—1,435 visits per 100,000 for females compared to 531 for males. In contrast, the female rate for all ED visits was only 1.2 times higher than the rate for males. Gender differences were greatest for migraine headaches, where females visited the ED at 4.6 times the rate observed among males (557 compared to 121 visits per 100,000 population). Similarly, most ED visits for headache were made by females (73.5 percent), with gender differences even more pronounced for migraine headaches (82.6 percent of visits were for females).

The vast majority of ED visits for headaches (97.0 percent) were treated and released, compared with only 82.3 percent of all ED visits. ED visits resulted in hospital admission for 3.6 percent of patients with migraine compared to 2.4 percent for all headaches combined.

ED visits by age and income

As shown in figure 1, the highest rate of ED visits for headaches was for the 18 to 44 year age group (1,626 ED visits per 100,000 population) and the lowest rate was for the under-18 year group (345 per 100,000 population).

Figure 1

Rate of first-listed headache diagnosis ED visits per 100,000 population, by age group and income quartile, 2008. Note: Income quartile is based on the median household income of the patient’s ZIP Code of residence. Source: AHRQ, Center for Delivery, (more...)

The highest rate of ED visits for headache was among patients residing in the lowest income quartile (1,300 ED visits per 100,000 population). The rate of visits for headache was lower in each subsequent quartile, with patients from the wealthiest quartile having the lowest rate of visits (565 per 100,000 population). The rate of visits for patients in the lowest income quartile was 2.3 times higher than in the wealthiest income quartile—a pattern similar to all ED visits (data not shown).

ED visits by region, rural/urban location, and month

As shown in figure 2, the Midwest and South had the highest rates of ED visits for headaches—1,158 and 1,131 visits per 100,000 population, respectively. The Northeast and West had significantly lower rates at 809 and 744 visits per 100,000 population, respectively. This pattern differed from rates of all ED visits, where the Northeast had the highest ED visit rates overall closely followed by the Midwest and South, and the West had the lowest rates (data not shown).

Figure 2

Rate of first-listed headache diagnosis ED visits per 100,000 population, by hospital region and rurality, 2008. Note: Urban areas include large and small metropolitan; rural areas include micropolitan and not metropolitan or micropolitan. Source: AHRQ, (more...)

Patients in rural areas had higher rates of ED visits for headaches (1,425 per 100,000) compared to urban areas (896 per 100,000), a pattern similar to all ED visits (data not shown).

As shown in figure 3, the number of ED visits with a first-listed headache diagnosis varied by month, and patterns were similar for migraine and other headaches. In 2008, the number of visits increased in the summer months and peaked in September. February and December had the lowest numbers of ED headache visits.

Figure 3

First-listed headache diagnosis ED visits, by month, 2008. Source: AHRQ, Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project, Nationwide Emergency Department Sample, 2008

Inpatient stays for headache as a first-listed diagnosis

In 2008, there were 222 hospitalizations per day with headache as the first-listed diagnosis, at an aggregate cost of nearly $408 million for the year. A total of 51,100 of the 81,000 stays for headache (63.1 percent) were for migraine headaches (table 3).

Table 3

Characteristics of headache-related inpatient stays, 2008.

The mean length of stay for headaches was 2.7 days, about 40 percent shorter than the average hospital stay of 4.6 days. The average cost per headache stay was about 46 percent less expensive than the average overall ($5,000 versus $9,200); however, the average cost per day for headaches stays was comparable to the average cost per day for all inpatient stays ($1,900 versus $2,000 per day).

The hospitalization rate for all headaches was 2.9 times higher for females than males, and for migraines, the rate was 3.7 times higher among females. In comparison, the overall hospitalization rate was only 1.4 times higher in females versus males. Compared with all inpatient stays, headache stays were more likely to be for females (74.7 percent versus 58.5 percent) and to be for younger patients (43.7 years for headache patients versus 48.5 years overall).

Inpatient stays by age, region and month of admission

As shown in figure 4, the highest rate of hospitalization for headaches was for 45 to 64 year olds (35.7 per 100,000 population), followed by 18 to 44 year olds (32.6 per 100,000 population). This is in contrast to the findings for headache-related ED visits, which were significantly higher among 18 to 44 year olds than any other age group.

Figure 4

Rate of first-listed headache diagnosis inpatient stays per 100,000 population, by age group and hospital region, 2008. Source: AHRQ, Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project, Nationwide Inpatient Sample, (more...)

The West had the lowest rate of inpatient stays for headache (17.5 per 100,000 population) compared to the three other regions, which had rates ranging from 27.5 to 32.1 per 100,000 population. This is in contrast to the findings for ED visits, where the Northeast and the West were comparably low.

There were no differences in hospitalization rates by urban/rural location and income.

As shown in figure 5, the number of inpatient stays for headaches varied by month and differed somewhat for migraine and other headaches. Migraine headache stays had a low during February, peaked during October, and reached their lowest point in December. The number of stays for other headaches held steady from January to April then increased during July to October, declining again in November and December.

Figure 5

First-listed headache diagnosis inpatient stays, by month of admission, 2008. Source: AHRQ, Center for Delivery, Organization, and Markets, Healthcare Cost and Utilization Project, Nationwide Inpatient Sample, 2008

Diagnoses

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 13,600 ICD-9-CM diagnosis codes.

Case definition

The ICD-9-CM codes defining headaches include diagnosis codes in the following range: 307.81; 339.00–339.89; 346.00–346.93; and 784.0.

ICD-9-CM codes 346.00–346.93 identify migraine headaches specifically.

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 OB-GYN, ENT, orthopedic, cancer, pediatric, public, and academic medical hospitals. Excluded are long-term care, rehabilitation, psychiatric, and alcoholism and chemical dependency hospitals. Please note, a discharge of this nature will be included in the NIS if it occurred in a community hospital.

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 and Medicaid Services (CMS).⁴ Costs will tend to reflect the actual costs of production, while charges represent what the hospital billed for the case. For each hospital, a hospital-wide cost-to-charge ratio is used because detailed charges are not available across all HCUP States. Hospital charges reflect the amount the hospital charged for the entire hospital stay and does not include professional (physician) fees. For the purposes of this Statistical Brief, costs are reported to the nearest hundred.

Hospital location

The classification of whether a hospital is in an urban or rural area is defined using simplified groupings of the 2003 version of Urban Influence Codes. Urban areas are metropolitan counties. Rural areas are counties that are micropolitan or non-metropolitan/non-micropolitan.

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.

Region

Region is one of the four regions defined by the U.S. Census Bureau:

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Northeast: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, and Pennsylvania

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Midwest: Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, and Kansas

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South: Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida, Kentucky, Tennessee, Alabama, Mississippi, Arkansas, Louisiana, Oklahoma, and Texas

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West: Montana, Idaho, Wyoming, Colorado, New Mexico, Arizona, Utah, Nevada, Washington, Oregon, California, Alaska, and Hawaii