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While there is no cure for asthma, symptoms can typically be improved.[130] A specific, customized plan for proactively monitoring and managing symptoms should be created. This plan should include the reduction of exposure to allergens, testing to assess the severity of symptoms, and the usage of medications. The treatment plan should be written down and advise adjustments to treatment according to changes in symptoms.[131]

There are significant obstacles to accurate calculation and reporting of asthma incidence and prevalence (Croisant, 2014). Within the United States, diagnostic criteria are fairly uniform; however, a lack of uniformity in reporting leads to complexity in data acquisition and analysis (Croisant, 2014). This is complicated further internationally by issues related to differences in training level of healthcare providers, diagnostic criteria, and access to medical care (Croisant, 2014). Despite the difficulties in consistency and accuracy of data on incidence and prevalence, there is widespread consensus that both have increased substantially since 1970, both in the United States and globally (Croisant, 2014).

United States
In the United States, the Centers for Disease Control and Prevention undertakes asthma surveillance programs (Croisant, 2014). Data is collected through surveys carried out by the National Center for Health Statistics (Croisant, 2014). State-level data are obtained through the Behavioral Risk Factor Surveillance System and the Asthma Call Back survey (Croisant, 2014).

International
Various surveys have been used to estimate the global burden of asthma (Croisant, 2014). These include the European Community Respiratory Health Survey and the International Study of Asthma and Allergies in Children (Croisant, 2014). In addition, the World Health Organization has conducted the World Health Survey, the results of which can be used to estimate both within country and between country comparisons (Croisant, 2014).

Demographics
In any context, the health burden of asthma is heterogeneous. This occurs because there are so many factors that influence the development of the condition. (Carr & Bleecker, 2016; Divekar & Calhoun, 2014). These include host, agent, genetic, and environmental factors (Divekar & Calhoun, 2014). Host factors include the individual’s geographic location, body weight, and nutrition status (Divekar & Calhoun, 2014). Agent factors involve the infections to which the individual has been exposed (e.g., Respiratory Syncytial Virus) (Divekar & Calhoun, 2014). Genetic factors refer to the susceptibility based on the presence of genes related to pathogenesis, while environmental factors include things such as air quality, pollen, molds, and weather (Divekar & Calhoun, 2014). The interaction of these effects leads to variable progression of the disease, resulting in wide population heterogeneity (Carr & Bleecker, 2016). The between country and within country variations in prevalence indicate that environment is an important aspect of asthma prevalence (Beasley, 1998).

Incidence and Prevalence
1 in 13 people in the United States have asthma. The overall prevalence is 7.8%. The prevalence is 8.4% in children and 7.6% in adults. The prevalence is 6.5% in males (9.9% in children and 5.4% in adults) and 9.1% in females (6.9% in children and 9.7% in adults).

Morbidity and Mortality
The economic burden of asthma in the United States is high. The cost of asthma, in terms of medical treatment and lost productivity, was estimated to be $56 billion in 2009 (Carr & Bleecker, 2016). Asthma exacerbations number some 40,000, including over 5,000 visits to an emergency department and more than 1,200 hospital admissions, per day (Carr & Bleecker, 2016). Asthma is also the leading cause of missed school days among school-aged children (Carr & Bleecker, 2016). The overall mortality rate from asthma is 10.3 per million (CDC 2017). The morality rate is 3.0 per million for children and 13.7 per million for adults (CDC 2017).

Trends
Between 2001 and 2009, asthma prevalence increased across all demographic groups (Carr & Bleecker, 2016). This trend is expected to continue.

Incidence and Prevalence
Globally, asthma affects as many as 334 million people (Global Asthma Network, 2014). The worldwide estimate of prevalence rate in children is around 14%, while it is estimated to be around 8.6% in young adults between the ages of 18 and 45 (Global Asthma Network, 2014). The five countries with the highest prevalence of asthma among 18-45 year olds are “Australia (21.5%), Sweden (20.2%), UK (18.2%), Netherlands (15.3%), and Brazil (13.0%)” (To, 2012). Generally, the highest prevalence rates are seen in Latin American; in English-speaking countries Europe, North America, and Australasia; and in South America (Global Asthma Network, 2014). The prevalence is lowest in the Indian subcontinent, Asia-Pacific, the Eastern Mediterranean, and Eastern Europe (Global Asthma Network, 2014). In a study of 18-45 year olds, the prevalence in African countries was generally on the lower end, averaging around 4% (To, 2012). There is heterogeneity in prevalence among Asian countries; however, the prevalence rate tends to be lower than in Western countries, averaging below 5% (Song, 2014). In Asia, the prevalence is somewhat higher in the elderly population (Song, 2014).

Morbidity and Mortality
Morbidity information is particularly difficult to estimate in low resource populations (Cruz 2007). Mortality is estimated to be approximately 250,000 people per year (Cruz 2007). The worldwide age adjusted mortality rate is estimated to be 170 per million for males and 90 per million for females, though there is wide between country variabilty in mortality rates (Global Asthma Network, 2014). There is not a linear relationship between prevalence and mortality because globally, mortality is inversely correlated with availability of health care services, particularly drug therapy (Cruz 2007).

Trends
In all countries, the prevalence of asthma has increased as the prevalence of atopy has also increased since approximately 1970 (Cruz 2007). Asthma appears to be increasing with urbanization globally (Cruz 2007). Although longitudinal data on Asian countries is less readily available, it does appear that prevalence is increasing as it is elsewhere (Song, 2014). It is expected that there will be an additional 100 million people living with asthma by 2025 (Cruz 2007). In high income countries, asthma intervention programs have reduced hospitalizations and mortality (Cruz 2007). Where mortality is decreasing in low resource settings, this is largely related to an increase in the availability of controller medications (Cruz 2007).

Race and Ethnicity
Minority status is a risk factor for increased prevalence of asthma (Milligan, Matsui & Sharma, 2016). The overall prevalence is 7.8% among non-Hispanic Whites (7.4% in children and 7.9% in adults) (CDC 2017). The overall prevalence among non-Hispanic Blacks is 10.3% (13.4% in children and 9.1% in adults) (CDC 2017). Among Hispanics the overall prevalence is 6.6% (8% among children and 5.9% among adults) (CDC 2017). The mortality rate attributable to asthma is substantial higher among non-Hispanic Blacks (CDC 2017). The mortality rate for non-Hispanic Whites is 8.4 per million and 7.3 for Hispanics, while it is 23.9 per million for non-Hispanic Blacks. Keet et al. performed a stratified analysis of asthma prevalence of over twenty-three thousand children in more than five thousand census tracts (2011). The analysis demonstrated a racial disparity in the prevalence of asthma (Keet et al., 2011). Overall, the highest prevalence was among non-Hispanic Blacks (17.1%, 95% CI, 15.6–18.8) and Puerto Ricans (19.8%, 95% CI, 16.6–23.5%), while non-Hispanic Whites (9.6%, 95% CI, 8.9–10.3%), Hispanics (8.8%, 95% CI, 7.8–10.0) and Asians (8.1%, 95% CI, 6.5–10.0) all had lower prevalence (Keet et al., 2011). Black race and Puerto Rican ancestry remained statistically significant even after controlling for “neighborhood poverty, urban/rural status, region, sex, age and birth in the U.S.” (Keet et al., 2011).

Urban-Rural
Landmark research resulting from the 1988 National Health Interview Study found a strong correlation between urban residence and asthma in children (Aligne et al., 2000). Various environmental factors have been proposed to explain the phenomenon. More recent research contradicts these findings (Keet et al., 2011). Keet et al. discuss the fact that early research on “urban asthma” was performed on urban centers where populations were disproportionately minority with high levels of poverty (2011). Shifting demographics, including the “suburbanization of poverty” and “reverse migration” of African Americans from the North to the less urban South, with Hispanics moving into urban centers, has resulted in a less easily stratified urban demographic (Keet et al., 2011). Consequently, in this research urban status was not an independent risk factor for asthma (Keet et al., 2011). In addition, research demonstrates that there are risk factors for asthma that are somewhat specific to rural environment. For example, increased exposure to livestock has long been associated with decreased prevalence of wheezing (Wong, 2008). On the other hand, pesticides are associated with increased risk of wheezing in farmers (Hoppin, 2017).

Poverty
Poverty appears to be an independent risk factor for asthma in the United States(Keet et al., 2011). Increases in income result in substantial reduction in asthma prevalence (CDC 2016b). Prevalence is 19.4% when income is under $15,000, but drops to 11.5% when income is over $75,000 (CDC 2016b).

Prematurity
Prematurity has been proposed as an independent risk factor for the development of asthma (Milligan, Matsui & Sharma, 2016). However, there is a high correlation between prematurity and other independent risk factors for asthma, such as race and poverty status (Milligan, Matsui & Sharma, 2016).

Obesity
Obesity is likewise considered to be an independent risk factor for asthma (CDC 2013). The obesity rate is substantially higher among people with asthma as compared to the rate among people who do not have asthma (CDC 2013).

Education
Higher education level appears to confer some protection from asthma (CDC 2016a). By education level, those without a High School diploma have the highest prevalence of asthma, at 15.2% (CDC 2016a). A high school degree reduces prevalence to 13.2%, and those with a college degree have a prevalence of 11.2% (CDC 2016a).

Urbanized/Westernized-Developing Countries
Asthma is considered to have “plateaued” in urbanized cultures and continues to increase in developing countries (Wong, 2013). However, in some very urban and economically developed cities in Asia, such as Singapore, Hong Kong, and Seoul, asthma prevalence rates remain substantially lower than in the United States and Europe (Wong, 2013). It is posited that this results from a “complex interplay between between genetic factors and changing environmental exposure.” (Wong, 2013).

Urban-Rural Locations
Internationally, variability in asthma prevalence of people with similar genetic background between urban and rural locations may help illucidate the extent of the role of racial and genetic factors (Wong, 2013). Research demonstrates a substantially higher prevalence of asthma among urban children compared to children living in rural environemnts in China (Wong, 2001). This increased prevalence is not seen among individuals who move to the city later in life, indicating the possibility of some early life protective factors (Wong 2001). Survey research in Northern Europe has failed to demonstrate an urban-rural gradient in asthma prevalence in that region, although the same research seems to indicate that exposure to livestock still seems to offer some protection (Timm et al., 2015).

Poverty
There are many aspects of asthma that are critically important in populations in poverty. Asthma inhibits a person’s ability to attend school and work (Cruz 2007). The costs of health care, such as doctor and hospital visits and medications, are expensive, individually and for the system (Cruz 2007). In low resources communities, this can have a significant negative effect on a child’s school and on a family’s income and finances (Cruz 2007). Prevalence has historically been higher in high-income countries, but recent decades have seen an increase in prevalence in low- and middle-income countries, with a plateau in rates in high-income countries (Carr & Bleecker, 2016). The result has been a reduction in the prevalence disparity (Carr & Bleecker, 2016).

Biomass Burning
There is a positive association between exposure to biomass burning and development of respiratory conditions. One study has demonstrated that exposure to burning of sugar cane increases risk of asthma symptoms in Honduran children (Herrara-Camino, 2014). Another study in China found an association between wheeze and gas cooking (Wong, 2004).

Location Specific
Some risk factors for asthma may be highly location specific. For example, gas released from volcanic activity in Hawaii may be associated with increased asthma prevalence in children (Tam, 2014).