EPA's Report on the Environment: External Review Draft
Note to reviewers of this draft revised ROE: This indicator reflects data through 2010. EPA anticipates updating this indicator in 2014.
Asthma is a chronic respiratory disease characterized by inflammation of the airways and lungs. During an asthma attack, the small airways leading to the air sacs in the lungs are constricted and inflamed, and as a result, less air is able to flow out of the lungs. Asthma attacks can cause a multitude of symptoms ranging in severity from mild to life-threatening. These symptoms include wheezing, breathlessness, chest tightness, and coughing. Currently, there is no cure for asthma; however, people who have asthma can still lead productive lives if they control their asthma (NHLBI, 2012). Taking medication and avoiding contact with environmental “triggers” can help control asthma.
A family history of asthma contributes to susceptibility, but mostly what causes the development of asthma is unknown. Environmental exposures such as environmental tobacco smoke, dust mites, cockroach allergen, outdoor air pollution (e.g., ozone, particulate matter), pets, and mold are considered important triggers of an asthma attack (CDC, n.d., 2012; U.S. EPA, 2005, 2007).
Statistics for lifetime diagnosis prevalence, current asthma prevalence, and asthma attack prevalence are based on national estimates from the National Health Interview Survey (NHIS), conducted by the Centers for Disease Control and Prevention’s (CDC’s) National Center for Health Statistics (NCHS). The NHIS is the principal source of information on the health of the civilian non-institutionalized population of the U.S. and since 1960 has been one of the major data collection programs of NCHS. For this indicator, lifetime asthma diagnosis is defined as the number of adults/children who reported that they had ever been told by a doctor or other health practitioner that they had asthma. To determine current asthma prevalence, adults/children who had ever received an asthma diagnosis from a healthcare practitioner were asked whether they still have asthma. Asthma attack prevalence is based on the number of adults/children with an asthma diagnosis who reported an asthma episode or attack in the past 12 months.
What the Data Show
From 2008 to 2010, approximately 8.2 percent of the U.S. population reported that they currently have asthma (NCHS, 2012c; data not shown). Reported asthma rates are highest in the child and adolescent population.
In adults, an increase in asthma prevalence rates (i.e., lifetime diagnosis) is evident from 1997 to 2001, with some decrease after 2001 and subsequent increase after 2003 (Exhibit 1). From 1997 to 2010, the prevalence rates range from a low of 85 cases per 1,000 in 1999 to a high of 131 cases per 1,000 in 2009. Asthma was consistently higher among adult females than males. The asthma prevalence rates (i.e., ever had asthma) also consistently decrease in older populations. In 2010, the age-specific rates were 136 (ages 18-44 years), 121 (ages 45-64), 117 (ages 65-74 years), and 105 (ages 75+ years) cases per 1,000. These prevalence rates represent a small decrease compared to the previous year (i.e., 2009).
Exhibit 2 compares asthma rates across racial and ethnic groups for the 2008–2010 time period. The lifetime asthma diagnosis in adults was highest among blacks (142 cases per 1,000), followed by American Indians/Alaska Natives (129 cases per 1,000), whites (127 cases per 1,000), and Asians (92 cases per 1,000). Blacks reported the highest rate of current asthma prevalence across racial groups (91 cases per 1,000), followed by American Indians/Alaska Natives (84 cases per 1,000), whites (75 cases per 1,000), and Asians (48 cases per 1,000). Asthma attack prevalence rates were highest among American Indians/Alaska Natives, but otherwise followed a similar pattern to the reporting of current asthma prevalence.
Exhibit 2 also compares all three asthma prevalence categories for total Hispanics, non-Hispanic whites, and non-Hispanic blacks. For lifetime asthma diagnosis in adults, 102 cases per 1,000 were reported in total Hispanics, 133 cases per 1,000 in non-Hispanic whites, and 142 cases per 1,000 in non-Hispanic blacks.
In 2010, over 10 million children within the U.S. (age 0-17 years) were reported as ever having a diagnosis of asthma and over 4 million reported experiencing an asthma episode or attack during the previous 12 months (NCHS, 2012b; data not shown).
As shown in Exhibit 3, asthma prevalence rates increased on average approximately 4 percent per year between 1980 and 1996 (Akinbami et al., 2009). Rates in subsequent years (1997-2010), reported in two of the three asthma categories (current asthma and asthma attack prevalence), show no sharp upward or downward change through most of the time period. More fluctuation is reported for lifetime asthma, with rates ranging from a low of 108 cases per 1,000 in 1999 to a high of 138 cases per 1,000 in 2008 and 2009. Since tracking began in 2001, current asthma prevalence has ranged from approximately 83 cases per 1,000 (2002) to 96 cases per 1,000 (2009). Between 1997 and 2010, asthma attack prevalence rates have varied slightly, with the lowest rate of 52 per 1,000 occurring in 2005 and again in 2007 and the highest rate of 58 cases per 1,000 occurring in 2002. As shown in Exhibit 4, male children consistently had higher rates of asthma prevalence than female children, a pattern opposite of that reported in adults.
The overall pattern of asthma prevalence across races in children during 2008–2010 is similar to that seen in adults (Exhibit 5). This is true, even when comparing lifetime and current asthma prevalence in black children with American Indian/Alaska Native children. During the 2008-2010 period, reported lifetime asthma diagnosis was highest among black children (213 cases per 1,000), followed by American Indians/Alaska Natives (131 cases per 1,000), whites (122 cases per 1,000), and Asians (104 cases per 1,000). This exhibit also shows a similar pattern observed among children as seen with adults, with a higher number of cases of lifetime asthma, current asthma, and asthma attack observed among non-Hispanic blacks than non-Hispanic whites and total Hispanics.
The NHIS questionnaire underwent major changes in 1997, and the data presented focus on surveys conducted from 1997 to the most currently available release (2010). The redesigned NHIS is different in content, format, and mode of data collection from earlier versions of the survey. Due to changes in methodology 1997-2010 NHIS estimates are not directly comparable to pre-1997 NHIS estimates.
- Prevalence data reported in the NHIS are based on self-reported responses to specific questions pertaining to airway-related illnesses, and are subject to the biases associated with self-reported data. Self-reported data may underestimate the disease prevalence being measured if, for whatever reason, the respondent is not fully aware of his/her condition.
- Except where otherwise noted, all prevalence data are based on crude rates and are not age-adjusted, as CDC did not report age-adjusted data prior to 2002 in the data sources used for this indicator. Because the possible influence of subgroup age structure has not been removed, the reported disease prevalence rates across time or within different race and gender subgroups may reflect differences in the age distribution of the populations being compared.
Asthma prevalence data were obtained from annual reports published by NCHS (NCHS, 2002a-d; 2003a-f; 2004a,b; 2005a,b; 2006a-d; 2007a,b; 2008a,b; 2009a,b; 2010a,b; 2012a,b), which summarize health statistics compiled from the NHIS (http://www.cdc.gov/nchs/nhis/nhis_series.htm). Race and ethnicity data were obtained from CDC’s online “Health Data Interactive” (NCHS, 2012c) (http://www.cdc.gov/nchs/hdi.htm). The data used by CDC to create the asthma tables in “Health Data Interactive” originate from the NHIS. The pre-1997 data also originate from the NHIS, as compiled by NCHS in Akinbami et al. (2009).
For More Information
- CDC National Health Interview Survey Data, Asthma
- CDC's "Health Data Interactive"
- EPA: America's Children and the Environment
- National Surveillance of Asthma: United States, 2001-2010
- EPA's "Asthma Facts"
- Learn how this indicator fits into a conceptual diagram for: Tropospheric Ozone
- This indicator relates to: Disease and Conditions
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