NCHS Data Brief ■ No. 94 ■ May 2012

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Trends in Asthma Prevalence, Health Care Use, and

Mortality in the United States, 2001–2010

Lara J. Akinbami, M.D.; Jeanne E. Moorman, M.S.; Cathy Bailey, M.S.; Hatice S. Zahran, M.D.; 

Michael King, Ph.D.; Carol A. Johnson, M.P.H.; and Xiang Liu, M.Sc.

Key findings

• Asthma prevalence increased 

from 7.3% in 2001 to 8.4% 

in 2010, when 25.7 million 

persons had asthma.

• For the period 2008–2010, 

asthma prevalence was higher 

among children than adults, and 

among multiple-race, black, 

and American Indian or Alaska 

Native persons than white 

persons.

• From 2001 to 2009, health 

care visits for asthma per 100 

persons with asthma declined 

in primary care settings, while 

asthma emergency department 

(ED) visit and hospitalization 

rates were stable.

• For the period 2007–2009, 

black persons had higher 

rates for asthma ED visits 

and hospitalizations per 100 

persons with asthma than white 

persons, and a higher asthma 

death rate per 1,000 persons 

with asthma. Compared with 

adults, children had higher rates 

for asthma primary care and ED 

visits, similar hospitalization 

rates, and lower death rates.

Asthma is a common chronic airway disorder characterized by periods 

of reversible airflow obstruction known as asthma attacks (1). Airflow is 

obstructed by inflammation and airway hyperreactivity (contraction of the 

small muscles surrounding the airways) in reaction to certain exposures (1). 

Exposures include exercise, infection, allergens (e.g., pollen), occupational 

exposures (e.g., chemicals), and airborne irritants (e.g., environmental tobacco 

smoke) (1). Symptoms may include wheezing, coughing, shortness of breath, 

and chest tightness (1). It is not clear how to prevent asthma from developing 

and there is no cure (1). Yet the means to control and prevent exacerbations 

in persons who have asthma are well established in evidence-based clinical 

guidelines (1). This report presents recent data for trends in asthma prevalence, 

health care encounters, and mortality.

Keywords: lung disease • National Health Interview Survey • National Health 

Care Surveys • National Vital Statistics System

Asthma prevalence increased from 2001 to 2010 and is now 

at its highest level.

Figure 1. Asthma prevalence in the United States, 2001–2010

NOTES: Asthma prevalence refers to percentage of people who have ever been diagnosed with asthma and still have asthma. 

Data are age adjusted to the 2000 U.S. standard population. Access data table for Figure 1 at: http://www.cdc.gov/nchs/data/

databriefs/db94_tables.pdf#1.

SOURCE: CDC/NCHS, National Health Interview Survey.

0

2

4

Percent6

8

10

2001 2002 2003 2004 2005

Year

2006 2007 2008 2009 2010
NCHS Data Brief ■ No. 94 ■ May 2012

■  2  ■

Asthma prevalence (the percentage of people who have ever been diagnosed with asthma and still 

have asthma) increased from 7.3% in 2001 to 8.4% in 2010 (Figure 1). In 2010, an estimated 25.7 

million people had asthma: 18.7 million adults aged 18 and over, and 7.0 million children aged 

0–17 years.

Asthma prevalence was higher among children, females, and those with 

family income below the poverty level, and differed by race and ethnicity 

for the period 2008–2010.

Children aged 0–17 years had higher asthma prevalence (9.5%) than adults aged 18 and over 

(7.7%) for the period 2008–2010 (Figure 2). Females had higher asthma prevalence than males 

(9.2% compared with 7.0%). 

Among racial groups, persons of multiple race had the highest asthma prevalence (14.1%), while 

Asian persons had the lowest rates (5.2%). Persons of black (11.2%) and American Indian or 

Alaska Native (9.4%) races had higher asthma prevalence compared with white persons (7.7%). 

Among Hispanic groups, asthma prevalence was higher among persons of Puerto Rican (16.1%) 

than Mexican (5.4%) descent.

0246 8 10 12 14 16 18 20

Total

Child

Adult

Male

Female

White

Black

American Indian or

Alaska Native

Asian

Multiple race

Total Hispanic

Puerto Rican

Mexican

Less than 100% poverty

100% to less than

200% poverty

200% or more

of poverty

Figure 2. Asthma prevalence, by selected demographic characteristics: United States, average annual 2008–2010

NOTES: Asthma prevalence refers to percentage of people who have ever been diagnosed with asthma and still have asthma. Access data table for Figure 2 at: 

http://www.cdc.gov/nchs/data/databriefs/db94_tables.pdf#2. 

SOURCES: CDC/NCHS, Health Data Interactive and National Health Interview Survey.

Percent

95% confidence interval.
NCHS Data Brief ■ No. 94 ■ May 2012

■  3  ■

Asthma prevalence was higher for groups with lower income-to-poverty level ratios: While 

11.2% of those with incomes less than 100% of the poverty level had asthma, asthma prevalence 

was 8.7% for persons with incomes 100% to less than 200% of the poverty level, and 7.3% for 

persons with incomes at least 200% of the poverty level.

Asthma health care encounters per 100 persons with asthma declined 

in primary care settings and were stable for emergency department (ED) 

visits and hospitalizations, while asthma death rates per 1,000 persons with 

asthma declined.

Asthma visits in primary care settings (physician offices and hospital outpatient departments) 

per 100 persons with asthma declined from 2001 to 2009 (Figure 3). Asthma ED visits and 

hospitalizations per 100 persons with asthma were stable from 2001 to 2009. Asthma death rates 

per 1,000 persons with asthma declined from 2001 to 2009. 

Figure 3. Asthma health care encounters per 100 persons with asthma, and asthma deaths per 1,000 persons with 

asthma: United States, 2001–2009

0.1

1

10

100

2001 2002 2003 2004 2005 2006 2007 2008 2009

Rate (log scale)

Emergency department visits per 100 persons with asthma

Office and outpatient visits per 100 persons with asthma

Hospitalizations per 100 persons with asthma

Deaths per 1,000 persons with asthma

Year

NOTE: Access data table for Figure 3 at: http://www.cdc.gov/nchs/data/databriefs/db94_tables.pdf#3.

SOURCES: CDC/NCHS, National Ambulatory Medical Care Survey, National Hospital Ambulatory Medical Care Survey, National Hospital Discharge Survey, 

National Vital Statistics System, and National Health Interview Survey.

For the period 2007–2009, asthma health care encounters per 100 persons 

with asthma varied by demographic characteristics. 

The rates of health care encounters per 100 persons with asthma across all health care settings 

(Figure 4) were similar for males and females, and for black and white persons, but the rate for 

children was higher than that for adults. 

Asthma encounter rates for each setting (primary care, ED, and hospital) were also similar for 

males and females (Figure 4). 

Asthma visit rates in primary care settings per 100 persons with asthma were similar for black 

and white persons. However, black persons had a higher asthma ED visit rate and a higher asthma 

hospitalization rate than white persons. 
NCHS Data Brief ■ No. 94 ■ May 2012

■  4  ■

Figure 4. Asthma health care encounters per 100 persons with asthma: United States, 2001–2009

NOTE: Access data table for Figure 4 at: http://www.cdc.gov/nchs/data/databriefs/db94_tables.pdf#4. 

SOURCES: CDC/NCHS, National Ambulatory Medical Care Survey, National Hospital Ambulatory Medical Care Survey, National Hospital Discharge Survey, and 

National Health Interview Survey. Rate

0

20

40

60

80

100

Total Male Female White Black Child Adult

Hospitalizations

Emergency 

department visits

Physician office or

hospital outpatient 

department visits

Children aged 0–17 years with asthma had a higher asthma visit rate for primary care settings and 

a higher ED visit rate than adults aged 18 and over. Asthma hospitalization rates per 100 persons 

with asthma were similar between adults and children.

Asthma death rates per 1,000 persons with asthma were higher for females, 

black persons, and adults.

The asthma death rate per 1,000 persons with asthma was 0.15 for the period 2007–2009. Asthma 

death rates per 1,000 persons with asthma were more than 30% higher for females than males, 

Figure 5. Asthma deaths per 1,000 persons with asthma, by selected demographic characteristics: United States, 

average annual 2007–2009

NOTE: Access data table for Figure 5 at: http://www.cdc.gov/nchs/data/databriefs/db94_tables.pdf#5.

SOURCES: CDC/NCHS, National Vital Statistics System and National Health Interview Survey.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Rate

Total Male Female White Black Child Adult 0–14

years

15–34

years

35–64

years

65 years

and over
NCHS Data Brief ■ No. 94 ■ May 2012

■  5  ■

75% higher for black persons than white persons, and almost seven times higher for adults than 

children. The highest rate was for adults aged 65 and over (0.58 per 1,000 persons with asthma) 

(Figure 5). 

Summary

Asthma prevalence increased from 2001 to 2010: An estimated 25.7 million persons had asthma 

in 2010. Certain demographic groups had higher asthma prevalence: children aged 0–17 years, 

females, black persons, persons of multiple race, Puerto Rican persons, and persons with a 

family income below the poverty level. This report examines rates for asthma outcomes (health 

care encounters and death) for persons with asthma rather than for the general population. Rates 

for the general population represent the burden of asthma in the United States. Rates for the 

population with asthma take into account changes in asthma prevalence over time and differences 

in asthma prevalence among demographic groups. From 2001 to 2009, rates for ED visits and 

hospitalizations per 100 persons with asthma remained stable, while rates for asthma visits in 

primary care settings (physician offices or hospital outpatient departments) and asthma deaths 

declined. For the period 2007–2009, asthma visit rates (per 100 persons with asthma) in primary 

care settings for black persons were similar to those for white persons, but rates for asthma ED 

visits, hospitalizations, and death (per 1,000) were higher. Compared with adults, children aged 

0–17 years had a higher rate for asthma visits in primary care settings and EDs, but had a similar 

hospitalization rate and a lower asthma death rate. 

Definitions

Asthma prevalence: Based on an affirmative response to the following National Health Interview 

Survey (NHIS) questions: For adults, “Have you ever been told by a doctor or other health 

professional that you had asthma?” and “Do you still have asthma?”; and for children, “Has a 

doctor or other professional ever told you that [sample child] had asthma?” and “Does [sample 

child] still have asthma?”

Poverty status or percentage of poverty level: Based on family income, family size, and the 

number of children in the family, and for families with two or fewer adults, on the age of the 

adults in the family. The poverty level is based on a set of income thresholds that vary by family 

size and composition. Families or individuals with income below their appropriate thresholds are 

classified as below the poverty level. These thresholds are updated annually by the U.S. Census 

Bureau to reflect changes in the Consumer Price Index for all urban consumers (2). Estimates by 

poverty status from NHIS are based on both reported and imputed family income (3).

Asthma health care encounter: Based on an International Classification of Diseases, Ninth 

Revision, Clinical Modification (ICD–9–CM) code of 493 as the first-listed diagnosis from the 

National Ambulatory Medical Care Survey (NAMCS), National Hospital Ambulatory Medical 

Care Survey (NHAMCS), and National Hospital Discharge Survey (NHDS). For this report, 

office visits and outpatient department visits were combined because both occur in primary care 

(nonemergent) settings. 

Asthma death: Based on an ICD–10 code of J45 or J46 as the underlying cause of death from the 

National Vital Statistics System (NVSS).
NCHS Data Brief ■ No. 94 ■ May 2012

■  6  ■

Data sources and methods

NHIS data were used to estimate asthma prevalence. NHIS collects information about the health 

and health care of the civilian noninstitutionalized U.S. population. Data for this report were 

taken from the sample adult and sample child components that collect detailed information 

about health conditions, including asthma, for a randomly selected adult or child. For further 

information about NHIS including the questionnaire, see the NHIS website (available from http://

www.cdc.gov/nchs/nhis.htm).

NAMCS data were used to estimate visits to private physician offices. NAMCS is an annual 

probability survey of nonfederal office-based physicians who provide direct patient care in the 

50 states or the District of Columbia, excluding radiologists, anesthesiologists, and pathologists. 

Patient information is abstracted from medical records and includes demographics, diagnoses, 

medications, and procedures. Additional information can be found on the Ambulatory Health 

Care Data website (available from http://www.cdc.gov/nchs/ahcd.htm).

NHAMCS data were used to estimate visits to hospital outpatient departments and hospital 

EDs. NHAMCS is a national probability sample survey of in-person visits made to EDs and 

outpatient departments of nonfederal short-stay hospitals in the United States. Patient information 

is collected from medical records and includes demographics, diagnoses, medications, and 

procedures. More information can be found at the Ambulatory Health Care Data website 

(available from: http://www.cdc.gov/nchs/ahcd.htm).

NHDS data were used to estimate inpatient hospitalizations. NHDS collects information from 

a national sample of inpatient stays in nonfederal short-stay hospitals in the United States. 

Patient information is collected from medical records and automated data files and includes 

demographics, length of stay, diagnoses, and procedures. For more information, visit the NHDS 

website (available from http://www.cdc.gov/nchs/nhds.htm).

The mortality component of NVSS data was used to calculate asthma death rates. Data are based 

on information from all death certificates filed in the 50 states and District of Columbia. For more 

information, visit the NVSS Mortality Data website (available from http://www.cdc.gov/nchs/

deaths.htm).

Data from NHIS, NAMCS, NHAMCS, and NHDS are based on nationally representative 

samples. For these surveys, sample weights are used to produce national estimates. Dataweighting procedures are described in more detail elsewhere (4–6). Point estimates and estimates 

of corresponding variances for this analysis were calculated using SUDAAN software (7) to 

account for the complex sample designs of each survey. The Taylor series linearization method 

was used for variance estimation.

Differences between percentages and rates were evaluated using two-sided significance tests 

at the 0.05 level. Terms such as “higher than” and “less than” indicate statistically significant 

differences. Terms such as “similar” and “no difference” indicate that the statistics being 

compared were not significantly different. Lack of comment regarding the difference between 

any two statistics does not necessarily suggest that the difference was tested and found to be not 

significant.
NCHS Data Brief ■ No. 94 ■ May 2012

■  7  ■

Rates in this report are expressed relative to the estimate of the number of people with asthma 

from NHIS, and, therefore, account for prevalence differences over time and among subgroups. 

This approach is in contrast to the more common presentation of rates for the general population 

that reflect the overall burden of asthma in the United States. Population-based rates do not 

take into account increasing asthma prevalence over time or prevalence differences among 

demographic groups. Rates per 100 persons with asthma, however, can be used to directly 

compare the risk of an outcome (e.g., hospitalization or death) for subgroups due to factors other 

than a difference in current asthma prevalence. The population reference group for the prevalence 

estimates (civilian noninstitutionalized population) is different than the reference groups for 

hospital data (civilian population) and for mortality data (residential population). Therefore, the 

rates per 100 with asthma for these two outcomes may be slightly overestimated. Standard errors 

for the asthma-specific rates, which use the number of persons with asthma in the denominator 

rather than a population constant, were calculated using formulae for ratios assuming that 

covariance equals zero (8). 

All estimates shown in this report have a relative standard error less than or equal to 30%. 

Trends were tested with weighted least squares regression models of the log of each outcome 

using Joinpoint software (9) to determine whether an apparent change over time was statistically 

significant, taking into account the standard error for each data point. 

About the authors

Lara J. Akinbami and Xiang Liu are with the Centers for Disease Control and Prevention’s (CDC) 

National Center for Health Statistics, Office of Analysis and Epidemiology. Jeanne E. Moorman, 

Cathy Bailey, Hatice S. Zahran, Michael King, and Carol A. Johnson are with CDC’s National 

Center for Environmental Health and the National Asthma Control Program.

References

1. National Heart, Lung, and Blood Institute, National Institutes of Health. National Asthma 

Education and Prevention Program. Expert Panel Report 3: Guidelines for the diagnosis and 

management of asthma. NIH Publication No. 07–4051. 2007.

2. U.S. Census Bureau. Poverty. 2011. Available from: http://www.census.gov/hhes/www/

poverty/.

3. Schenker N, Raghunathan TE, Chiu PL, et al. Multiple imputation of family income and 

personal earnings in the National Health Interview Survey: Methods and examples. National 

Center for Health Statistics. 2010. Available from: http://www.cdc.gov/nchs/data/nhis/tecdoc4.

pdf.

4. Botman SL, Moore TF, Moriarity CL, Parsons VL. Design and estimation for the National 

Health Interview Survey, 1995–2004. National Center for Health Statistics. Vital Health Stat 

(2)130. 2000.

5. National Center for Health Statistics. Ambulatory Health Care Data: Estimation procedures. 

Available from: http://www.cdc.gov/nchs/ahcd/ahcd_estimation_procedures.htm [Accessed 

1/25/12].
U.S. DEPARTMENT OF

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PENALTY FOR PRIVATE USE, $300

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PERMIT NO. G-284

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6. Dennison C, Pokras R. Design and operation of the National Hospital 

Discharge Survey: 1988 redesign. National Center for Health Statistics. Vital 

Health Stat 1(39). 2000.

7. SUDAAN, release 10.0 [computer software]. Research Triangle Park, 

NC: RTI International. 2008.

8. Kish L. Survey Sampling. 1st ed. New York, NY: John Wiley & Sons, Inc. 

1965.

9. National Cancer Institute. Joinpoint regression program. 2011. Available 

from: http://srab.cancer.gov/joinpoint/.

Suggested citation

Akinbami LJ, Moorman JE, Bailey C, et al. 

Trends in asthma prevalence, health care 

use, and mortality in the United States, 

2001–2010. NCHS data brief, no 94. 

Hyattsville, MD: National Center for Health 

Statistics. 2012.

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

Edward J. Sondik, Ph.D., Director

Jennifer H. Madans, Ph.D., Associate 

Director for Science

Office of Analysis and Epidemiology

Jennifer H. Madans, Ph.D., Acting Associate 

Director

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DHHS Publication No. (PHS) 2012–1209

CS231460