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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