Asthma is a common disorder that affects approximately 15 million Americans. Although the largest effects of asthma are on quality of life (e.g., chronic activity limitations, missed school days, poor self-perceived health), dangerous asthma exacerbations are quite common. In the United States, asthma exacerbations account for 2 million emergency department visits annually, and 500,000 hospitalizations. More than 5,500 Americans actually die from asthma every year. These are preventable deaths. In monetary terms, asthma costs at least $6 billion per year, with more recent estimates from the NIH exceeding $11 billion. Approximately 50% of the economic impact is associated with emergency department visits, hospitalization, and death - in other words, expenditures related to asthma exacerbations rather than the management of chronic, stable asthma. No matter how you describe it, the problem is big and . it's growing.

Over the last 20 years, the prevalence of asthma in the US has increased dramatically. In the early 1970s, a national survey by the Public Health Service estimated that 3% of the US population has asthma. The most recent figures put asthma prevalence at somewhere between 4 to 8%. An exact estimate is not available. If one assumes 6%, this would represent a 100% increase in asthma prevalence over the past 25 years. If we put this in absolute terms, that means an additional 8 to 10 million Americans with asthma. Several studies suggest that the increase has been greater among children than adults. For example, between 1980 and 1994, asthma increased 160% among children age 0-4 and 74% among children age 5-14. Among adults age 35-64, the increase was 59%. The increase also has been greater among women than men. For example, between 1980 and 1994, asthma increased 92% among women and 60% among men. Although data are less consistent, it appears that asthma prevalence also may be rising more among African-Americans and Hispanics than among whites. For decades, African Americans have had consistently higher asthma prevalence rates than whites.

Although some portion of the increase may be due to improved recognition of asthma, the increases are much too large for this explanation alone. The speed of the epidemic also argues against a genetic explanation, though genetic tendencies toward asthma undoubtedly play a role. Thus, the dramatic increase in asthma prevalence is most likely due to widespread changes in behavioral and environmental causes for asthma. Differences in asthma prevalence (or severity) across different geographic areas provide important clues regarding the causes of asthma, and can assist health planners responsible for controlling the current epidemic. For example, at a global level, many have observed that asthma tends to be more common in developed nations, where indoor living, lack of exposure to certain childhood infections, sedentary living, and obesity are more common. Could these factors be related to asthma? Similar studies also indicate that asthma is largely an urban phenomenon. For example, more than 20% of US asthma deaths in one year occurred in New York City and Chicago, even though these places had only 7% of Americans with asthma. Why? What is it about these places that increases risk?

As with other chronic diseases, many different factors are probably responsible. Some of the factors that have been related to asthma, and which require further study, include: increased rates of prematurity (and premature infant survival), decreased rates of breastfeeding, unfavorable changes in the outdoor environment (e.g., air pollution), unfavorable changes in the indoor environment (e.g., smoking, indoor allergens, irritant gases), changes in socioeconomic status, changes in diet and physical activity (and development of obesity), and changes in the medical care environment (i.e.access to medical care, pharmacotherapy). Surprisingly, in 1999, we still lack a good understanding of how these factors relate to one another and of their relative importance in causing asthma. Further research is urgently needed in this arena, with particular attention to the role of early life factors, cockroach allergen, childhood infections, and obesity. For an American child in the inner city, living in a run-down tenement building, spending hours upon hours watching television, afraid to go outside due to the fear of violence . one can easily imagine his or her dramatically increased risk of developing asthma. The more we understand this complex picture, the better we can identify potential targets for intervention and assist those responsible for designing and implementing such programs.

With the exception of asthma mortality, considerably less data are available about acute asthma - that is, asthma exacerbations that require modification of chronic asthma management. Although such exacerbations often can be managed by patients without contact with doctors or the hospital system - if patients are properly instructed - many(possibly most) asthma exacerbations in the US continue to generate acute asthma "encounters" such as urgent office visits, ED visits, and hospitalizations.

I strongly encourage you to dedicate more federal funds toward studying this problem. Specifically, we need to support researchers who are quite eager to tackle this problem but lack the resources to conduct the clinical research that is required. For example, what can we do to better treat and prevent these asthma attacks? Among patients who experience near-fatal events, what can we do to prevent them from returning for another hospital admission, or, even worse, dying from this very treatable disease?

Emergency department visits provide a window into the magnitude and nature of the problem. In the US, emergency department visits have climbed from 1.2 million in the late 1980s to almost 2 million this year. In response to this situation, a group of emergency physicians formed a voluntary organization called the Multicenter Airway Research Collaboration (or MARC). With the assistance of a small grant from the National Heart, Lung, and Blood Institute, and several unrestricted grants from industry, I and my colleagues have managed to build a network of more than 80 emergency departments across North America that conducts research on asthma exacerbations (http://healthcare.partners.org/marc).

Preliminary data from this collaboration reveal several important findings. For example, more than 90% of children who present to the emergency department with an asthma attack actually have a primary care provider. Despite this, two-thirds go directly to the emergency department when having problems with their asthma and one-third rely on the emergency department for all of their asthma medications. Since emergency physicians are trained to manage emergencies, with little emphasis on preventive medicine, this may explain why most of these children are not on any preventive medications. There is a strong interest among academic emergency physicians to better understand how to make this cultural change, how to link better with primary care doctors, how to approach the emergency department visit as a "teachable moment" .. These efforts need your support.

The apparent overall increase in asthma morbidity and mortality, and differential asthma burden in specific sociodemographic groups, all have important implications for clinical care, research, and health policy. At a patient level, the relative lack of attention to epidemiological and clinical issues, particularly the management of asthma exacerbations, has led us to provide relatively unfocused therapy for a remarkably diverse group of patients. Indeed, one might marvel at how well current therapies work for what is, undoubtedly, a mixture of asthma subtypes. A better understanding of the biological and environmental causes of asthma would allow us to better target treatments for these asthma subtypes. Identification of the factors that have led to the current asthma epidemic and, more specifically, to the increased burden in specific demographic groups, also may have direct implications for clinical care (e.g., asthma prevention in high-risk individuals). Clearly, more research is needed in this arena. At a societal level, current efforts to describe the US asthma burden are sufficient to provide us with gross estimates but little more. Asthma affects at least 5% of all Americans, is increasing, and already exacts an enormous toll on American society - in terms of direct health care costs, as well as missed school and work days. The problem is of sufficient magnitude that it merits increased attention from the health policy planners. We can and must do something to reduce this burden of suffering.

Better asthma surveillance data also are needed to assist effective health policy planning, including the provision of adequate access to health care. Numerous studies suggest that specific groups (i.e., children, women, African Americans, and inner city inhabitants) bear a disproportionate percentage of the US asthma burden, and that public health efforts might be best focused on these populations. Research is needed on the most effective educational and interventional strategies for each group, particularly in the emergency department where a large number of these high-risk patients routinely seek care.

There is persuasive evidence that asthma prevalence is rising in the US and, for that matter, worldwide. Despite numerous research challenges, methodologically strong research can and must be conducted to reduce the burden of asthma exacerbations on the US health care system. The frequency of asthma exacerbations is rising, as demonstrated by dramatic increases in the annual number of asthma-related emergency department visits. The distribution of asthma varies dramatically by age, sex, race, and socioeconomic status. Although every demographic group is affected, certain groups (i.e., children, women, African Americans, and inner city inhabitants) appear to bear a disproportionate percentage of the asthma burden in the US. It is difficult to ascribe the current asthma epidemic to any single underlying factor; however, environmental factors, such as indoor allergens and obesity, and unequal access to medical care clearly play major roles. Greater funding is urgently needed to study the causes and treatments of asthma. Furthermore, we should strive to broadly implement effective treatment and preventive measures, promoting equal access to these benefits for all Americans.

Reprinted with permission.