As of 2011, ~235 million people worldwide were affected by asthma, and approximately 250,000 people die per year from the disease. Low and middle income countries make up more than 80% of the mortality. Rates vary between countries with prevalences between 1 and 18%. It is more common in developed than developing countries. One thus sees lower rates in Asia, Eastern Europe and Africa. Within developed countries it is more common among those who are economically disadvantaged while in contrast in developing countries it is more common amongst the affluent. The reason for these differences is not well known. While asthma is twice as common in boys as girls, severe asthma occurs at equal rates. Among adults, however, asthma is twice as common in women as men.
Increasing frequency
Rates of asthma have increased significantly between the 1960s and 2008 with it being recognized as a major public health problem since the 1970s. Some 9% of US children had asthma in 2001, compared with just 3.6% in 1980. The World Health Organization reports that some 10% of the Swiss population have asthma as of 2007, compared with 2% some 25–30 years ago. In the United States the age-adjusted prevalence of asthma increased from 7.3 to 8.2 percent during the years 2001 through 2009.
Region specific data
United States
Asthma affects approximately 7% of the population of the United States and causes approximately 4,210 deaths per year. In 2005, asthma affected more than 22 million people, including 6 million children, and accounted for nearly 500,000 hospitalizations that same year. In 2010, asthma accounted for more than one-quarter of admitted emergency department visits in the U.S. among children aged 1–9 years, and it was a frequent diagnosis among children aged 10–17 years. From 2000 through 2010, the rate of pediatric hospital stays for asthma declined from 165 to 130 per 100,000 population, respectively, whereas the rate for adults remained about 119 per 100,000 population. Asthma prevalence in the U.S. is higher than in most other countries in the world, but varies drastically between ethnic populations. Asthma prevalence is highest in Puerto Ricans, African Americans, Filipinos, Irish Americans, and Native Hawaiians, and lowest in Mexicans and Koreans. Rates of asthma-related hospital admissions in 2010 were more than three times higher among African American children and two times higher for African American adults compared with White and Asian and Pacific Islander people. Also, children who are born in low-income families have higher risk of asthma. Asthma prevalence also differs between populations of the same ethnicity who are born and live in different places. U.S.-born Mexican populations, for example, have higher asthma rates than non-U.S. born Mexican populations that are living in the U.S.
United Kingdom
Asthma affects approximately 5% of the United Kingdom’s population. In England, an estimated 261,400 people were newly diagnosed with asthma in 2005; 5.7 million people had an asthma diagnosis and were prescribed 32.6 million asthma-related prescriptions.
Canada
Data depicts an increasing trend in asthma prevalence among Canada’s population. In 2000-2001 asthma prevalence was monitored at 6.5%; by 2010-2011 a 4.3% increase was shown, with asthma prevalence totaling 10.8% of Canada's population. Furthermore, asthma prevalence varies among the provinces of Canada; the highest prevalence is Ontario at 12.1%, and the lowest is Nunavut at 3.8%. Though there is an overall decrease in the incidence of new asthma cases in Canada, prevalence is rising. This can be attributed to a decrease in case-specific mortality due to improved management and control of asthma and its symptoms.
Latin and Central America
It is approximated that 40 million Latin Americans live with asthma. In some reports, urban residency within Latin America has been found to be associated with an increased prevalence of asthma. Childhood asthma prevalence was found to be higher than 15 percent in a majority of Latin American countries. Similarly, a study published relating to asthma prevalence in Havana, Cuba estimated that approximately 9 percent of children under the age of 15 are undiagnosed for asthma, possible due to lack of resources in the region.
Asia
Data regarding the epidemiology of asthma in the continent of Asia as whole is scarce, particularly regarding adult populations. However, similarly to much of the rest of the globe, prevalence of childhood asthma appears to be rising. Systematic childhood studies, such as the International Study of Asthma and Allergies in Childhood, provide data regarding the epidemiology of asthma among Asia's youth population. Asthma prevalence among Asia’s adult population is less clear in comparison due to the comparatively higher monitoring of younger populations. However, the data available points to a positive correlation between age and asthma prevalence. Findings indicate that the prevalence of asthma among the Asian adult population is less than 5%; while findings pertaining to elderly populations illustrate a rate somewhere between 1.3-15.3%.
International migration
In a review of studies on the prevalence of asthma among migrant populations, those born in high-income countries were found to have higher rates of asthma than migrants. Second-generation migrants had a higher risk of asthma than first-generation migrants, and the prevalence of asthma increases with longer time of residence in the host country. This confirms the role of the environment in the development of asthma.
