Asthma is a chronic
respiratory disease characterized by episodes or attacks of
inflammation and narrowing of small airways in response to
asthma "triggers." Asthma attacks can vary from mild to life-threatening
and involve shortness of breath, cough, wheezing, chest pain
or tightness, or a combination of these symptoms. Many factors
can trigger an asthma attack, including allergens, infections,
exercise, abrupt changes in the weather, or exposure to airway
irritants, such as tobacco smoke.
The burden from asthma in the United States has increased
over the past 2 decades. Trends from 1980 to 1999 are presented
in the CDC Asthma Surveillance Survey. This fact sheet presents
the most recent national data on asthma gathered by the Centers
for Disease Control and Prevention. Age-adjusted rates by
race/ethnicity and gender are presented in the charts and
may be used to compare asthma prevalence, morbidity and mortality
between race/ethnicity and gender groups. Crude rates by race/ethnicity
and gender are presented in Table 1 to show the actual burden
of asthma among subgroups of the population. To compare groups,
it is strongly recommended that age-adjusted estimates be
used.
Table 1. Crude rates for current asthma
and asthma attack prevalence, 2001, and health care utilization,
and mortality, 2000
Prevalence, 2001: Lifetime asthma
diagnosis, current asthma, and asthma attack prevalence
Respondents in the National Health Interview Survey are asked
if they were ever told by a health professional that they
had asthma. In 2001, 31.3 million people (114 people per 1,000)
had ever been diagnosed with asthma during their lifetime
(Figure 1). Among adults, 109 per 1,000 had a lifetime asthma
diagnosis (22.2 million) compared to 126 per 1,000 children
0-17 years (9.2 million). Non-Hispanic blacks were 4% more
likely to have ever been diagnosed with asthma than non-Hispanic
whites and about 30% more likely than Hispanics. Females were
about 10% more likely than males to ever have been diagnosed
with asthma.
Beginning with the 2001 National Health
Interview Survey (NHIS), it is possible to make estimates
of the population that reported having asthma at the time
of the interview. This is referred to as current asthma prevalence
and includes people who have been diagnosed with asthma by
a health professional and who still have asthma. In 2001,
73 people per 1,000 or 20.3 million people, had asthma at
the time of the interview (Figure 2). Rates decreased with
age; 87 per 1,000 children 0-17 years (6.3 million children)
had asthma compared to 69 per 1,000 adults 18 years and over
(14 million adults). When race/ethnicity is considered, current
asthma prevalence was about 10% higher among non-Hispanic
blacks compared to non-Hispanic whites and about 40% higher
compared to Hispanics. Females had a 30% higher prevalence
compared to males. However, this pattern was reversed among
children. The current asthma prevalence rate for boys aged
0-17 years (99 per 1,000) was over 30% higher than the rate
among girls (74 per 1,000).
Asthma attack prevalence, or the number
of people who had at least one asthma attack in the previous
year, is also available from the NHIS. The asthma attack prevalence
is a crude indicator of how many people have uncontrolled
asthma and are at risk for a poor outcome from asthma such
as hospitalization. In 2001, 43 people per 1,000 (12 million
people) had experienced an asthma attack in the previous year
(Figure 3). That is, about 60% of the people who had asthma
at the time of the survey had an asthma attack in the previous
year. Asthma attack prevalence also decreased with age; 57
per 1,000 children 0-17 years (4.2 million children) had an
asthma attack in the previous year compared to 38 per 1,000
adults aged 18 years and over (7.8 million adults). Non-Hispanic
blacks had an asthma attack prevalence about 20% higher than
non-Hispanic whites and almost 60% higher than Hispanics.
Females had an asthma attack prevalence almost 40% higher
than males.
Health Care Use, 2000
Health care use for asthma includes outpatient visits to doctors’
offices and hospital outpatient departments, visits to hospital
emergency departments (EDs), and hospitalizations. Information
about Hispanic ethnicity is not consistently available in
national health care utilization data, and therefore is not
presented. In 2000, there were 10.4 million outpatient asthma
visits to private physician offices and hospital clinics,
or 379 per 10,000 people (Figure 4). Children aged 0-17 years
had 4.6 million visits and an outpatient visit rate of 649
per 10,000 and adults 18 years and over had a rate of 285
per 10,000. Blacks had an office visit rate 40% higher than
whites, and females a 10% higher visit rate compared to males.
There were 1.8 million visits to EDs
for asthma in 2000, or 67 per 10,000 people (Figure 5). Children
aged 0-17 years had over 728,000 ED visits, a rate of 104
per 10,000. The ED visit rate was highest among children aged
0-4 years at 180 per 10,000. Adults 18 years and over had
54 ED visits per 10,000. The ED visit rate for blacks was
125% higher than that for whites, and for females, about 30%
higher than for males.
Mortality
In 2000, 4,487 people died from asthma, or 1.6 per 100,000
people (Figure 7). Among children, asthma deaths are rare.
In 2000, 223 children aged 0-17 years died from asthma, or
0.3 deaths per 100,000 children compared to 2.1 deaths per
100,000 adults aged 18 and over. Non-Hispanic blacks were
the most likely to die from asthma and had an asthma death
rate over 200% higher than non-Hispanic whites and 160% higher
than Hispanics. Females had an asthma death rate about 40%
higher than males.
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