NCHS Data Brief ■ No. 72 ■ August 2011

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Blood Pressure Measurements at Emergency Department 

Visits by Adults: United States, 2007–2008

Richard W. Niska, M.D., M.P.H., F.A.C.E.P.

Key findings

Data from the National 

Hospital Ambulatory 

Medical Care Survey

• Blood pressure (BP) is 

severely elevated at 16.3%, 

and moderately elevated at 

27.2%, of hospital emergency 

department (ED) visits. 

Severely and moderately 

elevated BPs are more 

common at ED visits than at 

visits to patients’ primary care 

providers in hospital outpatient 

departments and physician 

offices. 

• Severely and moderately 

elevated BPs are more common 

at ED visits by older age groups 

and men. 

• Severely elevated BP is more 

common at ED visits by nonHispanic black persons (19.7%) 

than by non-Hispanic white 

(15.3%) or Hispanic (15.3%) 

persons.

• Severely elevated BP is 

more common at ED visits by 

Medicare beneficiaries (19.6%) 

than by those with private 

insurance (16.3%) or Medicaid 

(14.1%), even when adjusted 

for age. Moderately elevated 

Key findings

• Blood pressure (BP) is 

severely elevated at 16.3%, and 

moderately elevated at 27.2%, 

of emergency department (ED) 

visits. Severely and moderately 

elevated BPs are more 

common at ED visits than at 

visits to patients’ primary care 

providers in hospital outpatient 

departments and physician 

offices. 

• Severely and moderately 

elevated BPs are more common 

at ED visits by older age groups 

and men. 

• Severely elevated BP is more 

common at ED visits by nonHispanic black persons (19.7%) 

than by non-Hispanic white 

(15.3%) or Hispanic (15.3%) 

persons.

• Severely elevated BP is 

more common at ED visits 

by Medicare beneficiaries 

(19.6%) than by those with 

private insurance (16.3%) or 

Medicaid (14.1%). Moderately 

elevated BP is more common 

at ED visits by uninsured 

patients than by privately 

insured patients or Medicaid 

beneficiaries.

Persistently elevated blood pressure (BP), or hypertension, is a major risk 

factor for atherosclerotic cardiovascular disease, congestive heart failure, and 

renal failure. In 2007–2008, 29% of U.S. civilians had hypertension. Only 

one-half of persons with hypertension had their BP under control, with lower 

rates for persons aged 18–39 years and Hispanic persons (1). Because elevated 

BP in the emergency department (ED) may reflect underlying hypertension, 

the American College of Emergency Physicians recommends that patients with 

systolic BP greater than 140 mm Hg or diastolic BP greater than 90 mm Hg be 

referred for follow-up (2). This brief describes the distribution of elevated BP 

readings in the ED. The data are presented by severity level because the risk of 

complications increases with the severity of underlying hypertension (3).

Keywords: hypertension • disparities • National Hospital Ambulatory Medical 

Care Survey • National Ambulatory Medical Care Survey

Elevated BP is more common at visits to EDs than at visits 

to primary care providers.

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NCHS Data Brief ■ No. 72 ■ August 2011

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• BP is moderately elevated at 27.2% of ED visits and severely elevated at 16.3% of ED 

visits. Both prevalence estimates are significantly greater than at visits to patients’ primary 

care providers in hospital outpatient departments (OPDs) and physician offices (Figure 1).

Elevated BP is more common at ED visits by older patients and men.

• The prevalence of severely elevated BP increases significantly for each older age group up 

to age 65 (Figure 2). There is no significant difference in the prevalence between age groups 

65–74 years and 75 years and over. 

• The prevalence of moderately elevated BP increases significantly for each older age group 

up to age 45 years. There are no significant differences among age groups 45–64 years, 

65–74 years, and 75 years and over.

• The prevalences of both moderately elevated (30.8%) and severely elevated (16.9%) BPs 

are significantly greater at ED visits by men compared with women (Figure 3).

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Severely elevated BP is more common at ED visits by non-Hispanic black 

persons than by non-Hispanic white or Hispanic persons.

• Compared with non-Hispanic black persons (19.7%), the age-adjusted prevalence of 

severely elevated BP was significantly less at ED visits by non-Hispanic white (15.3%) and 

Hispanic (15.3%) persons (Figure 4). 

• Compared with non-Hispanic white persons, the age-adjusted prevalence of moderately 

elevated BP was significantly less at ED visits by Asian persons.

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NCHS Data Brief ■ No. 72 ■ August 2011

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Elevated BP is more common at ED visits by Medicare beneficiaries and by 

uninsured patients.

• ED visits with Medicare as the primary expected payment source had the highest ageadjusted prevalence of severely elevated BP (19.6%) (Figure 5). The prevalence was 

significantly less at ED visits by patients with private insurance (16.3%) or Medicaid 

(14.1%).

• ED visits with Medicaid as the primary expected payment source had the lowest ageadjusted prevalence of moderately elevated BP (23.7%). The prevalence was significantly 

greater at ED visits by patients with private insurance (27.7%) and the uninsured (27.3%). 

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NCHS Data Brief ■ No. 72 ■ August 2011

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Summary

This brief shows that elevated BP readings are much more common at visits to the ED than at 

visits to outpatient primary care providers. Compared with the 27.0% prevalence found at visits to 

primary care providers, the combined visit prevalence of severely and moderately elevated BP in 

EDs is about 43.5%. Disproportionately affected subgroups include patients who are older, male, 

non-Hispanic black, Medicare beneficiaries, or uninsured.

One reason that elevated BP may be observed more frequently in the ED than at visits to primary 

care providers is that adults in less than optimal general health are more likely to use the ED than 

those in good health (4). Two national objectives related to prevention of heart disease and stroke 

are (a) to reduce the proportion of adults with hypertension and (b) to increase the proportion of 

adults with hypertension whose BP is under control (5). ED visits could provide opportunities to 

address elevated BP through patient education, initial treatment, and referral to primary care as 

deemed clinically appropriate. 

Definitions

BP levels: The BP abstracted into the ED Patient Record Form is the first BP reading to be 

recorded in the medical record for that visit. BP measurements were classified hierarchically 

starting with the more severely elevated measurement, followed by moderately elevated, mildly 

elevated, and not elevated, based on the criteria of the Seventh Joint National Committee (JNC–7) 

(3). BP was subdivided into four levels, which are summarized here for completeness. The current 

analysis concentrated on severely and moderately elevated BPs. 

• Severely elevated. Systolic 160 mm Hg or above or diastolic 100 mm Hg or above, 

corresponding to the JNC–7 stage 2 hypertension category. 

• Moderately elevated. Systolic 140–159 mm Hg or diastolic 90–99 mm Hg, corresponding to 

the JNC–7 stage 1 hypertension category.

• Mildly elevated. Systolic 120–139 mm Hg or diastolic 80–89 mm Hg, corresponding to the 

JNC–7 prehypertension category.

• Not elevated. Systolic less than 120 mm Hg and diastolic less than 80 mm Hg (recorded as 

P, PALP, DOPP, or DOPPLER, or left blank) (6).

About 4.2% of ED visits and 8.9% of primary care provider visits had no systolic BP recorded. 

These visits were deleted from the analysis.

Race and ethnicity: Race and Hispanic ethnicity are abstracted from the ED medical record and 

converted into a single combined variable that includes non-Hispanic white, non-Hispanic black, 

Hispanic white or black, Asian, Native Hawaiian or other Pacific Islander, American Indian 

or Alaska Native, and two or more races. National Hospital Ambulatory Medical Care Survey 

(NHAMCS) race data were missing for 14.9% of ED visits in 2007 and 16.0% in 2008. Ethnicity 

data were missing for 24.9% of ED visits in 2007 and 27.7% in 2008. Missing values were 

imputed for both race and Hispanic ethnicity. In this analysis, visits by Native Hawaiian or other 

Pacific Islander, American Indian or Alaska Native, and multiracial patients—together accounting 

for 1.6% of the sample—were not presented because of small sample sizes. 
NCHS Data Brief ■ No. 72 ■ August 2011

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Primary expected payment source: Payment type is abstracted from the ED medical record to 

include private insurance, Medicare, Medicaid, uninsured (self-pay, no charge, or charity), and 

other (worker’s compensation or other). Dual Medicare-Medicaid beneficiaries were recoded 

as Medicare. In this analysis, other (4.4%) and unknown (6.4%) payment sources were not 

presented.

Primary care provider: Visits at which the provider responded positively to a question asking 

whether he or she (office-based physician or community health center provider) or the facility 

(OPD) was the patient’s primary care provider.

Data sources and methods

All estimates are from the 2007 and 2008 NHAMCS ED visit files and, for comparison, from 

the NHAMCS OPD and National Ambulatory Medical Care Survey (NAMCS) physician 

office files. Both NHAMCS and NAMCS are conducted by the Centers for Disease Control 

and Prevention’s (CDC) National Center for Health Statistics (NCHS). NHAMCS is an annual, 

nationally representative survey of visits to nonfederal general and short-stay hospital EDs and 

OPDs. NAMCS is an annual, nationally representative survey of visits to nonfederal office-based 

physicians in the United States. The NAMCS sample contains a separate stratum of community 

health centers that includes physicians and nonphysician clinicians. More details about NHAMCS 

and NAMCS methodologies are available elsewhere (7–9). 

Analyses were restricted to visits by patients aged 18 and over. Estimates for race and ethnicity 

and for primary payment sources were adjusted for the five age groups defined in this report. 

Statistical differences between BP categories and the independent variables were analyzed using 

SUDAAN 9.1 (10) to account for the multistage sampling design. Significance was defined 

at the 0.05 level. Determination of statistical significance was based on the two-tailed t test. 

The Bonferroni procedure was used to establish the critical value for statistically significant 

differences based on the number of possible comparisons within a particular variable of interest. 

All differences noted in this report were statistically significant. Differences not mentioned in 

the text may or may not be statistically significant. Although data for the “other” and “unknown” 

categories are presented in the figures, these data were not included in the statistical comparisons. 

To assess the effect of increasing age on the prevalences of severely and moderately elevated BP, 

a Cochran-Mantel-Haenszel test of trend was performed in SUDAAN 9.1. 

About the author

Richard Niska is an emergency physician and epidemiologist with the Centers for Disease 

Control and Prevention’s National Center for Health Statistics, Division of Health Care Statistics.
NCHS Data Brief ■ No. 72 ■ August 2011

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References

1. Egan BM, Zhao Y, Axon RN. U.S. trends in prevalence, awareness, treatment, and control of 

hypertension, 1988–2008. JAMA 303(20):2043–50. 2010.

2. Decker WW, Godwin SA, Hess EP, Lenamond CC, Jagoda AS; American College of 

Emergency Physicians Clinical Policies Subcommittee (Writing Committee) on Asymptomatic 

Hypertension in the ED. Clinical policy: Critical issues in the evaluation and management of 

adult patients with asymptomatic hypertension in the emergency department. Ann Emerg Med 

47(3):237–49. 2006.

3. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA , Izzo JL Jr, et al. Seventh 

report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of 

High Blood Pressure. Hypertension. 42(6):1206–52. 2003.

4. Garcia TC, Bernstein AB, Bush MA. Emergency department visitors and visits: Who used the 

emergency room in 2007? NCHS data brief, no 38. Hyattsville, MD: National Center for Health 

Statistics. 2010. Available from: http://www.cdc.gov/nchs/data/databriefs/db38.htm.

5. U.S. Department of Health and Human Services. Healthy People 2020 topics and objectives: 

Heart disease and stroke. HDS–5.1 and HDS–12. Available from: http://www.healthypeople.

gov/2020/topicsobjectives2020/objectiveslist.aspx?topicid=21.

6. McCaig LF, Burt CW. National Hospital Ambulatory Medical Care Survey: 2001 emergency 

department summary. Advance Data from Vital and Health Statistics; no. 335. Hyattsville, MD: 

National Center for Health Statistics. 2003. Available from: http://www.cdc.gov/nchs/data/ad/

ad335.pdf.

7. National Center for Health Statistics. 2008 National Ambulatory Medical Care Survey. Publicuse data file documentation. Hyattsville, MD. 2010. Available from: http://www.cdc.gov/nchs/

ahcd/ahcd_questionnaires.htm.

8. National Center for Health Statistics. Community health center data from the 2006–2008 

National Ambulatory Medical Care Survey. Public-use data file documentation. Hyattsville, MD. 

Forthcoming.

9. National Center for Health Statistics. 2008 National Hospital Ambulatory Medical Care 

Survey. Public-use data file documentation. Hyattsville, MD. 2010. Available from: http://www.

cdc.gov/nchs/ahcd/ahcd_questionnaires.htm.

10.SUDAAN, release 9.2 [computer software]. Research Triangle Park, NC: RTI International. 

2009.
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NCHS Data Brief ■ No. 72 ■ August 2011

Suggested citation

Niska RW. Blood pressure measurements 

at emergency department visits by adults: 

United States, 2007–2008. NCHS data brief, 

no 72. Hyattsville, MD: National Center for 

Health Statistics. 2011.

Copyright information

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the public domain and may be reproduced 

or copied without permission; citation as to 

source, however, is appreciated.

National Center for Health 

Statistics

Edward J. Sondik, Ph.D., Director

Jennifer H. Madans, Ph.D., Associate 

Director for Science

Division of Health Care Statistics

Jane E. Sisk, Ph.D., Director

To receive this publication regularly, contact 

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ISSN 1941–4927 (Print ed.)

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