NCHS Data Brief ■ No. 194 ■ March 2015

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Trends in Emergency Department Visits for Ischemic Stroke 

and Transient Ischemic Attack: United States, 2001–2011

Anjali Talwalkar, M.D., M.P.H.; and Sayeedha Uddin, M.D., M.P.H.

Key findings 

Data from the National 

Hospital Ambulatory 

Medical Care Survey, 

2001–2011

● From 2001 through 2011, the 

rate of emergency department 

visits for ischemic stroke or 

transient ischemic attack (TIA) 

decreased 35% for patients 

aged 18 and over and 51% for 

patients aged 55–74. 

● From 2004 through 2011, 

the percentage of emergency 

department visits for ischemic 

stroke or TIA in which the 

patient arrived by ambulance 

decreased 41% for patients 

under 75. 

● The percentage of 

emergency department visits 

for ischemic stroke or TIA in 

which a magnetic resonance 

imaging (MRI) or computed 

tomography (CT) test was 

ordered or provided increased 

39% from 2001 through 2011.

● The percentage of 

emergency department visits 

for ischemic stroke or TIA 

that resulted in admission or 

transfer to a hospital increased 

10% from 2001 through 2011.

Stroke is the fifth leading cause of death in the United States (1). About 87% of all 

strokes are ischemic strokes (2). Transient ischemic attacks (TIAs) cause similar 

symptoms, but the blockage of blood flow to the brain is temporary. However, 

about one-third of people who have a TIA will have a stroke within 1 year (3). 

Emergency departments play a critical role in the diagnosis and management of 

ischemic stroke and TIA. The evaluation of these conditions in the emergency 

department is similar, so they are combined for this analysis. This report presents 

recent trends in visits to emergency departments for ischemic stroke or TIA.

Keywords: cerebrovascular disease • health care utilization • National Hospital 

Ambulatory Medical Care Survey (NHAMCS)

The total age-adjusted rate of emergency department visits for 

ischemic stroke or TIA for patients aged 18 and over decreased 

from 2001 through 2011, with the greatest decrease in visit 

rates seen in patients aged 55–74. 

0

50

100

150

200

250

300

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Visits per 10,000 persons

18–542

75 and over1,2

All1

Figure 1. Age-adjusted and age-specific emergency department visit rates for ischemic stroke or 

transient ischemic attack among patients aged 18 and over: United States, 2001–2011

1

Significant decreasing linear trend (p < 0.05). 2

Differences between each age group are statistically significant for each year (p < 0.05).

NOTES: Emergency department visits for ischemic stroke or transient ischemic attack are defined as codes 433–436 of the 

International Classification of Diseases, Ninth Revision, Clinical Modification for any of the three collected visit diagnoses. Estimates 

are age-adjusted by the direct method of standardization to the U.S. census 2000 standard population. Visit rates are based on the 

U.S. Census Bureau’s July 1 estimates of the civilian noninstitutionalized population of the United States in each survey year. 

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2001–2011.

55–741,2
NCHS Data Brief ■ No. 194 ■ March 2015

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Among patients aged 18 and over, the rate of emergency department visits for ischemic stroke 

or TIA decreased 35% from 40 per 10,000 persons in 2001 to 26 per 10,000 persons in 2011 

(Figure 1). The emergency department visit rate for ischemic stroke or TIA for patients aged 

55–74 decreased 51% from 68 visits per 10,000 persons in 2001 to 33 visits per 10,000 persons 

in 2011. The emergency department visit rate for ischemic stroke or TIA for patients aged 75 and 

over decreased 26% from 245 visits per 10,000 persons in 2001 to 182 visits per 10,000 persons 

in 2011. However, no change in visit rate for this age group was observed from 2006 through 

2011. The emergency department visit rate for ischemic stroke or TIA for patients aged 18–54 

did not change. Patients aged 75 and over had the highest rate of emergency department visits 

for ischemic stroke or TIA throughout the period. Patients aged 18–54 had the lowest rate of 

emergency department visits for ischemic stroke or TIA.

From 2004 through 2011, the percentage of emergency department 

visits for ischemic stroke or TIA in which patients arrived by ambulance 

decreased 41% for patients under 75. 

For patients under 75, the percentage of emergency department visits for ischemic stroke or TIA 

in which they arrived by ambulance decreased from 41% in 2004–2005 to 24% in 2010–2011 

(Figure 2). For patients aged 75 and over, the percentage of visits for ischemic stroke or TIA 

in which they arrived by ambulance did not significantly change from 2004 through 2011. 

Throughout the period, the percentage arriving by ambulance was higher for older patients than 

for those under 75. 

0

10

20

30

40

50

60

70

80

Percent of visits

41 37

33

24

55

61

65

57

Figure 2. Emergency department visits for ischemic stroke or transient ischemic attack with ambulance arrival, by age: 

United States, 2004–2011

1

Significant decreasing linear trend for visits by patients under age 75 (p < 0.05). 2

Differences between age groups are statistically significant for each year (p < 0.05).

NOTES: Emergency department visits for ischemic stroke or transient ischemic attack are defined as codes 433–436 of the International Classification of 

Diseases, Ninth Revision, Clinical Modification for any of the three collected visit diagnoses. Mode-of-arrival data are not available for 2001 and 2002. Data from 

2003 are not shown to make 2-year average estimates. 

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2004–2011.

75 and over2 Under 751,2

2004–2005 2006–2007 2008–2009 2010–2011
NCHS Data Brief ■ No. 194 ■ March 2015

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The percentage of emergency department visits for ischemic stroke or TIA 

with a magnetic resonance imaging (MRI) or computed tomography (CT) 

test ordered or provided increased 39% from 2001 through 2011.

The percentage of visits for ischemic stroke or TIA with an MRI or CT test increased from 66% 

in 2001 to 92% in 2011 (Figure 3). The percentage of visits for other diagnoses with an MRI or 

CT test also increased, but the rate of increase for MRI or CT testing was higher for ischemic 

stroke or TIA visits compared with other visits.

0

10

20

30

40

50

60

70

80

90

100

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Percent of visits

Other diagnoses1

Figure 3. Emergency department visits with magnetic resonance imaging or computed tomography test ordered or 

provided, by visit diagnosis: United States, 2001–2011

1

Significant increasing linear trend (p < 0.05). 2

Rate of increase for visits for ischemic stroke or transient ischemic attack is greater than for visits for other diagnoses (p < 0.05).

NOTE: Emergency department visits for ischemic stroke or transient ischemic attack are defined as codes 433–436 of the International Classification of 

Diseases, Ninth Revision, Clinical Modification for any of the three collected visit diagnoses.

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2001–2011.

Ischemic stroke or transient ischemic attack1,2
NCHS Data Brief ■ No. 194 ■ March 2015

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The percentage of emergency department visits for ischemic stroke or 

TIA admitted or transferred to another hospital increased 10% from 2001 

through 2011. 

The percentage of emergency department visits for ischemic stroke or TIA that resulted in 

admission or transfer to another hospital increased from 71% in 2001 to 78% in 2011 (Figure 4). 

The percentage of visits for other diagnoses that were admitted or transferred did not change. 

0

10

20

30

40

50

60

70

80

90

100

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Percent of visits

Other diagnoses

Figure 4. Emergency department visits admitted or transferred to another hospital, by visit diagnosis: United States, 

2001–2011

1

Significant increasing linear trend (p < 0.05).

NOTE: Emergency department visits for ischemic stroke or transient ischemic attack are defined as codes 433–436 of the International Classification of 

Diseases, Ninth Revision, Clinical Modification for any of the three collected visit diagnoses.

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2001–2011.

Ischemic stroke or transient ischemic attack1
NCHS Data Brief ■ No. 194 ■ March 2015

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Summary

While stroke remains a leading cause of death and disability in the United States, mortality from 

stroke has been declining. This report demonstrates that the age-adjusted emergency department 

visit rate for stroke or TIA has also been declining. Among specific age groups, visit rates for 

ischemic stroke or TIA decreased for patients aged 55 and over, with the largest decline seen 

for patients aged 55–74. While visit rates also declined for patients aged 75 and over from 2001 

through 2011, no significant decline was seen after 2006. Rates for patients aged 75 and over also 

remained the highest. No change in visit rates for patients aged 18–54 was seen. 

Changes in the resources used in the acute management of ischemic stroke and TIA have 

also occurred. Advanced imaging and admission or transfer to a hospital both increased at 

emergency department visits for ischemic stroke or TIA from 2001 through 2011. However, 

from 2004 through 2011, a decline in the percentage of visits in which patients under 75 arrived 

by ambulance was observed. Monitoring visits to emergency departments will continue to be 

important to assess the impact of public health campaigns to promote rapid emergency care of 

stroke and TIA and to describe the burden of these conditions on the U.S. health care system. 

Definitions

Ischemic stroke: Occurs when a blood vessel that carries oxygen and nutrients to the brain is 

blocked by an obstruction such as a blood clot. When that happens, part of the brain cannot get 

the oxygen it needs, so the brain cells die (3). 

Transient ischemic attack: Similar to an ischemic stroke, but the blockage of blood flow to the 

brain is temporary. There is usually no permanent injury to the brain cells (3). 

Emergency department visit for ischemic stroke or transient ischemic attack: A visit to a hospital 

emergency department with ischemic stroke or transient ischemic attack documented as any one 

of three diagnoses collected for that visit. 
NCHS Data Brief ■ No. 194 ■ March 2015

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Data source and methods

Data from the 2001–2011 National Hospital Ambulatory Medical Care Survey (NHAMCS) 

were analyzed. NHAMCS is an annual nationally representative survey of visits to nonfederal 

hospital-based outpatient departments, emergency departments, and ambulatory surgery centers. 

The survey uses a multistage probability sample design. A sample weight that takes all stages of 

design into account is computed for each sample visit. The survey data are weighted to produce 

unbiased national annual estimates of hospital-based ambulatory visits (4). 

Analyses included visits from the emergency department component of NHAMCS by patients 

aged 18 and over. Up to three visit diagnoses are collected for each sampled visit. A visit for 

ischemic stroke or TIA was defined as a visit with any listed diagnosis codes 433–436 based on 

the International Classification of Diseases, Ninth Revision, Clinical Modification. 

Data analyses were performed using the statistical packages SAS version 9.3 (SAS Institute, 

Cary, N.C.), SUDAAN version 10.0 (RTI International, Research Triangle Park, N.C.), and 

Stata version 12.0 (StataCorp, College Station, T.X.). Age-adjusted rates were calculated using 

the direct method and the 2000 U.S. census projected population for age groups 18–39, 40–59, 

60–79, and 80 and over (5). A weighted least-squares regression analysis was used to determine 

the significance of trends at the 0.05 level. Differences between rates of change for trends and 

between subgroups were evaluated with two-tailed t tests and a significance level of 0.05. 

About the authors

Anjali Talwalkar and Sayeedha Uddin are with CDC’s National Center for Health Statistics, 

Division of Health Care Statistics.
NCHS Data Brief ■ No. 194 ■ March 2015

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References

1. Kochanek KD, Murphy SL, Xu JQ, Arias E. Mortality in the United States, 2013. NCHS data 

brief, no 178. Hyattsville, MD: National Center for Health Statistics. 2014.

2. Go AS, Mozaffarian D, Roger VL, Benjamin EJ, Berry JD, Blaha MJ, et al. Heart disease 

and stroke statistics—2014 update: A report from the American Heart Association. Circulation 

129(3):e28–e292. 2014.

3. American Heart Association/American Stroke Association. Types of stroke. Available from: 

http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/Types-of-Stroke_

UCM_308531_SubHomePage.jsp.

4. NCHS. Public use data file documentation 2001–2011 National Hospital Ambulatory Medical 

Care Survey. Hyattsville, MD: National Center for Health Statistics.

5. Klein RJ, Schoenborn CA. Age adjustment using the 2000 projected U.S. population. Healthy 

People Statistical Notes, no. 20. Hyattsville, MD: National Center for Health Statistics. 2001.
NCHS Data Brief ■ No. 194 ■ March 2015

Suggested citation

Talwalkar A, Uddin S. Trends in emergency 

department visits for ischemic stroke and 

transient ischemic attack: United States, 

2001–2011. NCHS data brief, no 194. 

Hyattsville, MD: National Center for Health 

Statistics. 2015.

Copyright information

All material appearing in this report is in 

the public domain and may be reproduced 

or copied without permission; citation as to 

source, however, is appreciated.

National Center for Health 

Statistics

Charles J. Rothwell, M.S., M.B.A., Director

Nathaniel Schenker, Ph.D., Deputy Director

Jennifer H. Madans, Ph.D., Associate 

Director for Science

Division of Health Care Statistics

Clarice Brown, M.S., Director

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