(Chest. 2006;130:4S-12S.)
© 2006
American College of Chest Physicians
The Global Burden of Asthma*
Sidney S. Braman, MD, FCCP
* From the Division of Pulmonary and Critical Care Medicine, Brown University, Rhode Island Hospital, Providence, RI.
Correspondence to: Sidney S. Braman, MD, FCCP, Professor of Medicine, Brown University, Rhode Island Hospital, Division of Pulmonary and Critical Care Medicine, 593 Eddy St, Providence, RI 02903-4923; e-mail: sidney-braman{at}brown.edu
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Abstract
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There has been a sharp increase in the global prevalence, morbidity, mortality, and economic burden associated with asthma over the last 40 years, particularly in children. Approximately 300 million people worldwide currently have asthma, and its prevalence increases by 50% every decade. In North America, 10% of the population have asthma. Asthma is underdiagnosed and undertreated, although the use of inhaled corticosteroids has made a positive impact on outcomes. The increasing number of hospital admissions for asthma, which are most pronounced in young children, reflect an increase in severe asthma, poor disease management, and poverty. Worldwide, approximately 180,000 deaths annually are attributable to asthma, although overall mortality rates have fallen since the 1980s. Most asthma deaths occur in those 
45 years old and are largely preventable, frequently being related to inadequate long-term medical care or delays in obtaining medical help during the last attack. The financial burden on patients with asthma in different Western countries ranges from $300 to $1,300 per patient per year, disproportionately affecting those with the most severe disease. There are a number of significant barriers to reducing the burden of asthma, particularly in developing countries, where many patients have limited access to care and essential medications. The Global Initiative for Asthma has outlined a six-point patient management plan to address the effective handling of the increased number of patients in primary care. The plan focuses on patient education, written treatment plans, and ongoing communication and review with patients and their providers.
Key Words: asthma management • economic costs • morbidity • mortality • prevalence • respiratory disease
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Introduction
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The definition of bronchial asthma has been refined considerably since it was described in 1892 by Sir William Osler1 as: "... a neurotic affection characterized by hyperemia and turgescence of the mucosa of the smaller bronchial tubes and a peculiar exudate of mucin. The attacks may be due to direct irritation of the bronchial mucosa or may be induced reflexly, by irritation of the nasal mucosa, and indirectly, too, by reflex influences from stomach, intestines or genital organs." William Osler was, perhaps, one of the finest physicians in the English-speaking world at the turn of the twentieth century and an expert in the diagnosis of diseases of the cardiovascular and pulmonary systems. Over the years, researchers chiseled away at Osler’s definition and, by the mid-twentieth century, asthma was known as "... a disease characterized by widespread narrowing of the airways which alters in severity spontaneously or in response to specific treatment" (1959)2 and "... characterized by increased responsiveness of the trachea and bronchi to various stimuli" (1962).3 Today, asthma is defined as a chronic inflammatory disorder of the airways that affects adults and children of all ages (Table 1
).4
Improvements in asthma care were rapid during the second half of the twentieth century, and 1989 saw the inauguration of the Global Initiative for Asthma (GINA), regarded as the most authoritative road map for asthma care. GINA is a collaboration between the National Heart, Lung, and Blood Institute, the National Institutes for Health, and the World Health Organization in an effort to raise awareness of the increasing prevalence of asthma. The goals of asthma treatment, as laid out in the GINA workshop report, are shown in Table 2
.5 Essentially, the cornerstones of asthma management are an objective assessment, physician/patient partnership, control of environmental influences, and pharmacologic therapy.5
Asthma can place considerable limitations on the physical, emotional, social, and professional lives of sufferers, and these may be greater when symptoms are not adequately controlled. Children can become very distressed by their disease, with considerable absences from school and reduced participation in family life. There has been a sharp increase in the global prevalence, morbidity, mortality, and economic burden associated with asthma since the 1960s, particularly in children.46 Although asthma is most common in developed (westernized) countries, it is becoming increasingly common in developing countries, which is most likely related to the increased urbanization of communities. Four recent surveys, Asthma in America,7 Asthma Insights and Reality in Europe,89 Asthma Insights and Reality in Asia-Pacific,10 and Asthma Insights and Reality in Japan11 highlighted the fact that asthma is underdiagnosed and undertreated, with considerable room for improvement in asthma control (Fig 1
). Furthermore, there is a considerable communication "gap" between what physicians (providers) do and what their patients actually perceive that they do (Fig 2
).7 For example, 70% of physicians said that they had developed a written action plan for and with their patients, while only 27% of patients claimed that this was actually the case.
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Asthma Prevalence Initiatives
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Since 1989, GINA has collected asthma prevalence data from various surveys throughout 20 geographic regions, and compiled them to produce the Global Burden of Asthma report4 that was released in February 2004. Survey questionnaires were based on the symptom of "wheeze," which is a key symptom for identification of individuals with asthma. Wheezing occurring at any time over a 12-month period has good specificity and sensitivity for bronchial hyperresponsiveness and a diagnosis of asthma in adults and children. Most of the data were obtained from two key surveys: the International Study of Asthma and Allergies in Childhood6 (patients aged 6 to 7 years and 13 to 14 years), and the European Community Respiratory Health Survey12 (adults aged 20 to 44 years). Data in these two surveys were collected in a standardized manner between centers and in different countries.
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Global Asthma Prevalence
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Approximately 300 million people worldwide currently have asthma, with estimates suggesting that asthma prevalence increases globally by 50% every decade.4 Prevalences are high (> 10%) in developed countries and, although data are still missing (including data for much of Africa), rates are increasing in developing regions as they become more westernized (Fig 3
).4 There have also been sharp increases in South Africa and the countries of the former Eastern Europe, including the Baltic States. The most striking increases are seen among children (Fig 4
), with prevalence rates of > 30% in some areas (English-speaking populations), although the disease is also on the increase in the elderly.413
Prevalence in Developed Countries
The highest asthma prevalences are found in the United Kingdom (> 15%), New Zealand (15.1%), Australia (14.7%), the Republic of Ireland (14.6%), Canada (14.1%), and the United States (10.9%).4 One person in 10 has asthma in North America, approximately 35.5 million individuals. Certain ethnic groups, such as African Americans and Hispanics, have an even higher prevalence. In Western Europe, almost 30 million individuals now have asthma and the prevalence rate has doubled over the last decade.14 In the United Kingdom, one estimate suggests that 3.4 million people, namely 1 in every 7 children aged 2 to 15 years (1.5 million) and 1 in every 25 adults (1.9 million), have asthma symptoms requiring treatment.14 In Japan, the number of asthma patients treated by medical facilities is > 100 cases/d/100,000 population; 30 years ago, it was just 3 cases/d/100,000 population.4
Prevalence in Developing Countries
In developing regions (Africa, Central and South America, Asia, and the Pacific), asthma prevalence continues to rise sharply with increasing urbanization and westernization. Estimates suggest that > 40 million individuals in South and Central America and > 50 million individuals in Africa currently have the disease. High prevalences have been reported in Peru (13.0%), Costa Rica (11.9%), and Brazil (11.4%).4 In Africa, asthma prevalence is highest in South Africa (8.1%), perhaps the most westernized of the African countries.4 Almost 44 million people in the East Asia/Pacific region have asthma, although the prevalence rates vary markedly throughout the region. In Asia, increased prevalences are likely to be particularly dramatic in India and China. For example, a 2% increase in prevalence in China would lead to an additional 2 million asthma sufferers.
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Why Is Asthma Prevalence Increasing?
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Although understanding of many aspects of asthma has improved over the past decades, the fundamental causes of the disorder and the reasons for its increased prevalence remain largely unknown. Interestingly, the increase in asthma prevalence has been associated with a rise in atopic sensitization and a parallel increase in other allergic conditions (eg, eczema and rhinitis). Allergic sensitization appears to begin in utero. There is, undoubtedly, a genetic component to asthma, and it seems possible that changing patterns of environmental influences, such as exposure to microorganisms, pollutants, indoor and outdoor allergens, and diet, exert a strong influence on the development of the disease in susceptible individuals. It is also possible that the current definition of asthma (Table 1) is more inclusive, capturing patients who may not previously have been classified as having this disease.
Another influence on prevalence rates may be the fact that epidemiologic studies1516 indicate that children do not appear to be "growing out" of asthma. Although asthma may "disappear" in 30 to 50% of children, it does tend to reappear in adulthood; and even among those who do not have clinical symptoms, lung function may remain altered.15 Two thirds of asthmatic children still have symptoms at age 21 years, and 5 to 10% of those with "trivial" asthma as children will have severe disease as adults.16 This underlines the importance identifying and treating childhood disease.
Asthma prevalence in the elderly may actually be underestimated. In this population, lung function testing is more limited and patients are also less likely to complain about respiratory symptoms, regarding them, perhaps, as simply related to increasing age. Furthermore, asthma symptoms often overlap with those of other diseases commonly found among the elderly, including cardiovascular disease and COPD.13
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Morbidity and Mortality
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Most cases of asthma are diagnosed and managed at a primary care level. Current statistics show that there is significant morbidity and mortality among asthma sufferers, as illustrated in Figure 5
with data compiled by the National Asthma Campaign, a patient-support organization in the United Kingdom.14
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Figure 5. Estimate of asthma morbidity and mortality in a primary care organization (n = 330,000) in the United Kingdom. GP = general practitioner. Reproduced with permission from the European Respiratory Society.14
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Internationally, trends indicate an increasing number of hospital admissions for asthma, which is most pronounced in young children, and which reflects an increase in severe asthma, poor disease management, and poverty.1718 In Europe, acute asthma is the most common cause of hospital admission among children of all ages.14 In North America, while the number of hospital admissions for respiratory disease in general has fallen, the number of admissions for asthma has increased. In the United States, there was a 200% increase in hospitalization rates for adults with asthma and a 50% increase for asthmatic children between the 1960s and the 1980s.19 Furthermore, the rates of hospital admission for patients of color are 50% higher than for white patients and up to 150% higher if these patients are children.18 There are multiple reasons for these differences in admission rates, probably reflecting poverty, poor education, and inadequate access to medical care, in addition to the possible influences of ethnicity.
According to the recent Asthma in America survey,7 over a 12-month period approximately 9% of asthma patients required hospitalization, 23% needed emergency department treatment, and 29% had to have an unscheduled emergency appointment because of their asthma. Similarly, in the Asthma Insights and Reality in Europe survey,9 up to 27% of the UK sample needed acute health-care services for their asthma over the past year, including hospital, emergency department, and urgent care visits.
Worldwide, approximately 180,000 deaths are attributable to asthma each year,20 although there is considerable regional variation in mortality rates (Fig 6
).4 Overall mortality rates have fallen since the 1980s. This may be related to changes in asthma management, specifically in the increased use of management guidelines and inhaled corticosteroids.4 By contrast, trends for asthma mortality in the United States (approximately 5,000 deaths annually) show a progressive increase over the last 2 decades, with the highest rates among African-American and Hispanic populations, as well as in those who are poorly educated, live in large cities, or who are financially disadvantaged. In Europe, age-standardized mortality rates per 100,000 (1989 data) were as low as 0.08 for Greece and as high as 1.0 for England and Wales. Other countries with high mortality rates are Ireland (0.97), Luxembourg (0.91), West Germany (0.80), Belgium (0.78), and France (0.65).14 Most asthma deaths occur in those aged 45 years and are largely preventable, frequently being related to inadequate long-term medical care or to delays in obtaining medical help during the last attack. In a confidential inquiry into asthma deaths in Wales, 73.1% (n = 38) of the 52 patients < 65 years old who died from asthma were currently using inhaled corticosteroids, 4 patients were prescribed inhaled corticosteroids but charts suggested that the patients were noncompliant, and 21 patients were previously admitted to the hospital for asthma during the past 12 months.21 It seems that the underuse of corticosteroids—possibly related to noncompliance—played a causative role in the deaths of some patients.
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Economic Burden
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Globally, the economic costs associated with asthma exceed those of tuberculosis and HIV/AIDS combined.20 Developed economies can expect to spend 1 to 2% of their health-care budget on asthma.4 Investigations have shown22 that the financial burden on patients with asthma in different Western countries ranges from $300 to $1,300 per patient per year. In the United States, the total direct medical and indirect economic costs (ie, loss of school or work days, lost productivity, premature retirement) of asthma were approximately $12 billion in 1994, representing an increase of > 50% from just 10 years before, mainly because of an increase in indirect economic costs.18 The indirect costs represent not just costs relating to the patient but, if the patient is a child, also to their family; in England, 69% of parents or partners of parents of asthmatic children reported having to take time off work because of their child’s asthma, and 13% had lost their jobs.14
In Europe, the total cost of asthma currently hovers at approximately 
17.7 billion ($21.65 billion) per year. Outpatient costs account for the highest proportion at approximately 3.8 billion ($4.65 billion), followed by expenses for antiasthma drugs (3.6 billion, or $4.4 billion). Inpatient care accounts for a relatively minor cost of just 0.5 billion ($0.61 billion). As poor asthma control is responsible for significant work impairment, productivity losses add up to 9.8 billion ($11.99 billion) per year.14
The economic burden of asthma disproportionately affects those with the most severe disease. In both Western and developing countries, patients with severe asthma are responsible for approximately 50% of all direct and indirect costs, even though this patient population represents just 10 to 20% of all asthma sufferers.718 By contrast, the 70% of asthma patients with "mild" disease account for only 20% of total asthma costs.18 The impact of disease severity on costs has been quantified in a cohort of 318 asthmatic patients followed up prospectively for 1 year.23 Patients presenting with a broad range of asthma severity (intermittent, mild persistent, moderate persistent, severe persistent) were recruited by chest physicians throughout France and treated for 1 year according to customary clinical practice and international treatment guidelines. The overall costs of asthma, including individual direct costs (Fig 7
), indirect costs, and intangible quality of life costs, were all related to asthma severity.23 The authors23 commented that this was the first study in asthma patients that combined rigorous disease severity classification with the costs of asthma in large numbers of patients receiving real-world treatment.
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Reducing the Global Burden of Asthma
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Unfortunately, there are a number of significant barriers to reducing the burden of asthma (Table 3
).4 For the governments of much of the population of the world, asthma is not a health-care priority. In developing countries, many patients have very limited access to care and essential medications. In addition, asthma management must compete for access to this limited medical care and funding with other illnesses. For example, in Africa the most urgent health-care priorities are poor nutrition, poor housing, and infectious diseases (especially HIV/AIDS). However, even in developed countries, access to care and ongoing management may be suboptimal.7 The increasing prevalence of asthma implies a larger population of patients to manage, more patients with severe disease, a higher morbidity and mortality, and increasing expenditure. Underdiagnosis of asthma and the underuse of controller medication also complicate the picture, making early therapeutic intervention difficult and leading to increased exacerbations.
GINA guidelines stress that until there is a greater understanding of the factors that cause asthma, and measures become available to reduce its prevalence, the focus should be on cost-effective management approaches that are available to as many patients as possible. In addition to more research on the fundamental causes and pathogenesis of asthma, there are also urgent needs for the following: (1) effective patient management systems, particularly in primary care; (2) better (and more prompt) diagnosis; (3) better implementation of guidelines; and (4) more appropriate referral and treatment, including use of controller medications.
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GINA: Six-Point Asthma Management Program
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As part of its commitment to reducing the global burden of asthma, GINA has outlined a six-point patient management plan to address one of the greatest challenges: the effective handling of the increased numbers of asthma patients in primary care (Table 4
).4 The plan focuses on patient education, written medication plans, and ongoing communication and review with patients and their providers. The introduction of specialist asthma nurses in some European countries (eg, the United Kingdom, Sweden, and the Netherlands) has shown that this approach may reduce the burden on primary care physicians while improving overall patient care and conferring economic advantages.2425
As previously highlighted, the Asthma in America survey7 clearly demonstrated the gap in patient/provider communications, illustrating two different perspectives on asthma care. Patient education needs to start at the time of diagnosis and be integrated into every step of asthma care with the goal of guided self-management. Adherence, in particular, should be encouraged by maintaining clear, open lines of communication (Table 5
).
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Participant Feedback and Discussion
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Various aspects of Dr. Braman’s presentation were put to the participants of the American College of Chest Physicians symposium, with a specific focus on experiences in their own clinical practices. Questions addressed to the participants included the following: - What percentage of your clinical practice is dedicated to treating asthma?
- What percentage of your patients have asthma that is intermittent, mild persistent, moderate persistent, or severe persistent?
- Is there a consistent referral base from primary care?
- At what stage do you generally see referred patients?
- How do you see the growing burden of asthma in emerging countries?
- In general, there was widespread agreement with the data presented by Dr Braman?
Among the patients seen by participants in clinical practice, up to 60% of pediatric and 30% of adult patients have asthma. A proportion of patients included in global asthma prevalence statistics may actually have COPD because differential diagnosis of asthma from COPD or chronic asthma-like bronchitis remains a problem, even in countries considered to be leaders in asthma care (eg, Germany). Participants considered that up to 30% of patients may actually have both asthma and COPD. Overall, in the participants’ experience, 20 to 30% of patients have intermittent or mild persistent asthma, 50% have moderate persistent asthma, and 10 to 30% will have severe persistent disease. In line with the increasing incidence of asthma worldwide, highlighted by GINA, participants believed that they were now seeing more patients with asthma in their practices, typically 20 to 30% of all adult and 60% of all pediatric consultations.
Overall, it was believed that primary care physicians acknowledge their time constraints and recognize that more services may be available to asthma patients under specialist care, so these may act as drivers for referral, particularly among pediatric patients. Primary care physicians appear to be reluctant to make a diagnosis of a chronic disease in children. Feedback from the participants suggested that patients tend to be referred when they have either been classified as "uncontrolled" or during/following an acute exacerbation. While primary care physicians are likely to manage patients with mild persistent asthma, most patients with moderate persistent and severe persistent asthma are referred for specialist care. Approximately one third of participants thought that primary care physicians were "excellent" in their management of asthma, and two thirds thought them to be "reasonable." However, it was strongly believed that care systems need to be updated to support primary care physicians more effectively. In some situations, the involvement of specialist asthma nurses would greatly benefit physicians, particularly for patient evaluation and for the provision of education and advice.
In developing countries, public sectors are completely overwhelmed and the majority of patients will receive inadequate asthma care. In this setting, increasing urbanization is driving further increases in asthma incidence rates with consequent rises in morbidity and mortality rates. Thus, asthma needs to be recognized as a health priority in the developing world. In developed countries, issues relate more to the provision of ongoing management in primary care. Strategies to address this may include financial compensations for additional services, or financial incentives to set up such services. However, any financial systems need to be linked to improved outcomes and supported by high-quality training and educational resources.
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Conclusions
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Despite considerable knowledge with regard to the pathologic basis of asthma, the ongoing increases in asthma prevalence—and subsequent increases in morbidity and mortality—cannot yet be explained. In addition, the GINA goals of asthma management are not being achieved, with considerable underdiagnosis and underappropriate or inappropriate treatment. A significant proportion of patients are receiving only basic care and are not able to benefit from therapeutic advances. For the majority of the population of the world, asthma is a low public heath priority. The diversity of health-care systems worldwide and large variations in access to care require that asthma management guidelines to be tailored to local needs. More cooperation is imperative between health-care officials and primary and secondary care providers in order to develop individualized asthma management programs that will work at a local level.
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Acknowledgements
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The author thanks Carole Manners, PhD, for writing and editorial support in the development of this article.
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Footnotes
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Abbreviation: GINA = Global Initiative for Asthma
Dr. Braman has no conflict of interest or financial investment that would pertain to the substance of this article. However, he has been a consultant and has been on the speakers bureau of GlaxoSmithKline, Altana Pharma, BI, and Schering Plough Inc.
Received for publication July 2, 2005.
Accepted for publication March 20, 2006.
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References
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- Osler, W (1892) The principles and practice of medicine. D Appleton and Company. New York, NY:
- Ciba Guest Symposium.. Terminology, definitions and classifications of chronic pulmonary emphysema and related conditions. Thorax 1959;14,286-299[Medline]
- American Thoracic Society, Medical Section of the National Tuberculosis Association.. Chronic bronchitis, asthma, and pulmonary emphysema: a statement by the Committee on Diagnostic Standards for Non-tuberculous Respiratory Diseases. Am Rev Respir Dis 1962;85,762-768[ISI]
- Masoli, M, Fabian, D, Holt, S, et al Global Initiative for Asthma (GINA) program: the global burden of asthma: executive summary of the GINA Dissemination Committee report. Allergy 2004;59,469-478[CrossRef][ISI][Medline]
- Global Initiative for Asthma. GINA workshop report: global strategy for asthma management and prevention. Available at: http://www.ginasthma.com/wr_clean.pdf. Accessed October 22, 2004
- The International Study of Asthma and Allergies in Childhood (ISAAC) Steering Committee.. Worldwide variations in the prevalence of asthma symptoms: the International Study of Asthma and Allergies in Childhood (ISAAC). Eur Respir J 1998;12,315-335[Abstract]
- Asthma in America: a landmark survey. GlaxoSmithKline, 1998. Available at: http://www.asthmainamerica.com. Accessed May 15, 2006
- Asthma insights and reality in Europe: the Asthma Insights and Reality in Europe (AIRE) Study. Available at: www.asthma.ac.psiweb.com/. Accessed June 21, 2006
- Rabe, KF, Vermeire, PA, Soriano, JB, et al Clinical management of asthma in 1999: the Asthma Insights and Reality in Europe (AIRE) study. Eur Respir J 2000;16,802-807[Abstract]
- Lai, CK, De Guia, TS, Kim, YY, et al Asthma control in the Asia-Pacific region: the Asthma Insights and Reality in Asia-Pacific Study. J Allergy Clin Immunol 2003;111,263-268[CrossRef][ISI][Medline]
- Adachi, M, Morikawa, A, Ishihara, K Asthma insights and reality in Japan (AIRJ). Arerugi 2002;51,411-420[Medline]
- European Commission. European community respiratory health survey. Available at: www.ecrhs.org/. Accessed October 23, 2004
- Braman, SS Asthma in the elderly. Clin Geriatr Med 2003;19,57-75[CrossRef][ISI][Medline]
- European lung white book. 2003 European Respiratory Society and the European Lung Foundation. Brussels, Belgium:
- Martin, AJ, Landau, LI, Phelan, PD Asthma from childhood at age 21: the patient and his disease. BMJ (Clin Res Ed) 1982;284,380-382[ISI][Medline]
- Gerritsen, J, Koeter, GH, Postma, DS, et al Prognosis of asthma from childhood to adulthood. Am Rev Respir Dis 1989;140,1325-1330[ISI][Medline]
- Mitchell, EA International trends in hospital admission rates for asthma. Arch Dis Child 1985;60,376-378[Abstract]
- Beasley, R The burden of asthma with specific reference to the United States. J Allergy Clin Immunol 2002;109(5 Suppl),S482-S489
- Evans, R, III, Mullally, DI, Wilson, RW, et al National trends in the morbidity and mortality of asthma in the US. Prevalence, hospitalization and death from asthma over two decades: 1965–1984. Chest 1987;91(6 suppl),65S-74S
- World Health Organization. WHO factsheet 206: bronchial asthma. Available at: www.who.int/mediacentre/factsheets/fs206/en. Accessed October 23, 2004
- Burr, ML, Davies, BH, Hoare, A, et al A confidential inquiry into asthma deaths in Wales. Thorax 1999;54,985-989[Abstract/Free Full Text]
- Sullivan, S, Elixhauser, A, Buist, AS, et al National Asthma Education and Prevention Program working group report on the cost effectiveness of asthma care. Am J Respir Crit Care Med 1996;154,S84-S95[ISI][Medline]
- Godard, P, Chanez, P, Siraudin, L, et al Costs of asthma are correlated with severity: a 1-yr prospective study. Eur Respir J 2002;19,61-67
- Lindberg, M, Ahlner, J, Ekstrom, T, et al Asthma nurse practice improves outcomes and reduces costs in primary health care. Scand J Caring Sci 2002;16,73-78[CrossRef][ISI][Medline]
- Kamps, AW, Brand, PL, Kimpen, JL, et al Outpatient management of childhood asthma by paediatrician or asthma nurse: randomised controlled study with one year follow up. Thorax 2003;58,968-973[Abstract/Free Full Text]
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Abstract
Introduction
