The public health implications of asthma

Bousquet, Jean; Bousquet, Philippe J.; Godard, Philippe; Daures, Jean-Pierre

7. Ronchetti R, Villa MP, Barreto M, Rota R, Pagani J, Martella S, et al. Is the increase in childhood asthma coming to an end? Findings from three surveys of schoolchildren in Rome, Italy. European Respiratory Journal 2001;17:881-6.

8. Lee SL, Wong W, Lau YL. Increasing prevalence of allergic rhinitis but not asthma among children in Hong Kong from 1995 to 2001 (Phase 3 International Study of Asthma and Allergies in Childhood). Pediatric Allergy and Immunology 2004;15:72-8.

9. Federico MJ, Liu AH. Overcoming childhood asthma disparities of the inner-city poor. Pediatric Clinics of North America 2003;50:655-75.

10. Ait-Khaled N, Enarson DA, Behbehani N, Yeung MC, Irisen E. The Asthma Workshop. Report of a workshop organised by the International Union Against Tuberculosis and Lung Disease, Paris, 1516 December 2000. International Journal of Tuberculosis and Lung Disease 2001;5:973-7.

11. Haahtela T, Laitinen LA. Asthma programme in Finland 19942004. Report of a Working Group. Clinical and Experimental Allergy 1996;26 Suppl 1:1-24.

12. Murray CJ. Quantifying the burden of disease: the technical basis for disability-adjusted life years. Bulletin of the World Health Organization 1994;72:429-45.

13. Enarson DA, Ait-Khaled N. Cultural barriers to asthma management. Pediatric Pulmonology 1999;28:297-300.

14. The Bamako initiative. Lancet 1988;2:1177-8.

15. Ait-Khaled N, Auregan G, Bencharif N, Camara LM, Dagli E, Djankine K, et al. Affordability of inhaled corticosteroids as a potential barrier to treatment of asthma in some developing countries. International Journal of Tuberculosis and Lung Disease 2000;4:268-71.

16. Sterckx S. Patents and access to drugs in developing countries: an ethical analysis. Developing World Bioethics 2004;4:58-75.

17. Ait-Khaled N, Enarson D. Management of asthma guidelines. Guide for low income countries. IUATLD. Frankfurt am Main: pmi-Verlag Gruppe; 1996.

18. Veron LJ, Blanc LJ, Suchi M, Raviglione MC. DOTS expansion: will we reach the 2005 targets? International Journal of Tuberculosis and Lung Disease 2004;8:139-46.

19. Vandenplas O, Toren K, Blanc PD. Health and socioeconomic impact of work-related asthma. European Respiratory Journal 2003;22:689-97.

20. Malo JL, Lemiere C, Gautrin D, Labrecque M. Occupational asthma. Current Opinion in Pulmonary Medicine 2004;10:57-61.

21. Liss GM, Tarlo SM, Macfarlane Y, Yeung KS. Hospitalization among workers compensated for occupational asthma. American Journal of Respiratory Critical Care Medicine 2000;162:112-8.

22. Weiss KB, Sullivan SD. The health economics of asthma and rhinitis. I. Assessing the economic impact. Journal of Allergy and Clinical Immunology 2001;107:3-8.

23. Birnbaum HG, Berger WE, Greenberg PE, Holland M, Auerbach R, Atkins KM, et al. Direct and indirect costs of asthma to an employer. Journal of Allergy and Clinical Immunology 2002;109:264-70.

24. Van Ganse E, Laforest L, Pietri G, Boissel JP, Gormand F, Ben-Joseph R, et al. Persistent asthma: disease control, resource utilisation and direct costs. European Respiratory Journal 2002;20:260-7.

25. Godard P, Chanez P, Siraudin L, Nicoloyannis N, Duru G. Costs of asthma are correlated with severity: a 1-year prospective study. European Respiratory Journal 2002;19:61-7.

26. Schwenkglenks M, Lowy A, Anderhub H, Szucs TD. Costs of asthma in a cohort of Swiss adults: associations with exacerbation status and severity. Value in Health 2003;6:75-83.

27. Bootman JL, Crown WH, Luskin AT. Clinical and economic effects of suboptimally controlled asthma. Managed Care Interface 2004;17:31-6.

28. Maziak W, Mutius Ev E, Keil U, Hirsch T, Leupold W, Rzehak P, et al. Predictors of health care utilization of children with asthma in the community. Pediatric Allergy and Immunology 2004;15:166-71.

29. Amre DK, Infante-Rivard C, Gautrin D, Malo JL. Socioeconomic status and utilization of health care services among asthmatic children. Journal of Asthma 2002;39:625-31.

30. Gendo K, Sullivan SD, Lozano P, Finkelstein JA, Fuhlbrigge A, Weiss KB. Resource costs for asthma-related care among pediatric patients in managed care. Annals of Allergy Asthma and Immunology 2003;91:251-7.

31. Yeatts K, Shy C, Sotir M, Music S, Herget C. Health consequences for children with undiagnosed asthma-like symptoms. Archives of Pediatric and Adolescent Medicine 2003;157:540-4.

32. Lodha R, Puranik M, Kattal N, Kabra SK. Social and economic impact of childhood asthma. Indian Pediatrics 2003;40:874-9.

33. Bodenheimer T, Wagner EH, Grumbach K. Improving primary care for patients with chronic illness: the chronic care model. Part 2. JAMA 2002;288:1909-14.

34. Shames RS, Sharek P, Mayer M, Robinson TN, Hoyte EG, Gonzalez-Hensley F, et al. Effectiveness of a multicomponent self-management program in at-risk, school-aged children with asthma. Annals of Allergy, Asthma and Immunology 2004;92:611-8.

35. Lyseng-Williamson KA, Plosker GL. Inhaled salmeterol/fluticasone propionate combination: a pharmacoeconomic review of its use in the management of asthma. Pharmacoeconomics 2003;21:951-89.

36. Sullivan SD, Buxton M, Andersson LF, Lamm CJ, Liljas B, Chen YZ, et al. Cost-effectiveness analysis of early intervention with budesonide in mild persistent asthma. Journal of Allergy and Clinical Immunology 2003;112:1229-36.

37. Feenstra TL, Rutten-Van Molken MP, Jager JC, Van Essen-Zandvliet LE. Cost effectiveness of guideline advice for children with asthma: a literature review. Pediatric Pulmonology 2002;34:442-54.

38. Beckham S, Kaahaaina D, Voloch KA, Washburn A. A community-based asthma management program: effects on resource utilization and quality of life. Hawaii Medical Journal 2004;63:121-6.

39. Cowan S, Ernst P, Cartier A, Boulet LP. A population-based evaluation of a regional asthma education centre. Canadian Respiratory Journal 2004;11:39-44.

40. Sullivan SD, Weiss KB, Lynn H, Mitchell H, Kattan M, Gergen PJ, et al. The cost-effectiveness of an inner-city asthma intervention for children. Journal of Allergy and Clinical Immunology 2002;110:576-81.

41. Webber MP, Carpiniello KE, Oruwariye T, Lo Y, Burton WB, Appel DK. Burden of asthma in inner-city elementary schoolchildren: do school-based health centers make a difference? Archives of Pediatrics and Adolescent Medicine 2003;157:125-9.

42. New inner-city asthma interventions put social workers in the driver's seat. Disease Management Advisor 2003;9:111-5.

43. Griffiths C, Foster G, Barnes N, Eldridge S, Tate H, Begum S, et al. Specialist nurse intervention to reduce unscheduled asthma care in a deprived multiethnic area: the east London randomised controlled trial for high risk asthma (ELECTRA). BMJ 2004;328:144.

44. Lindberg M, Ahlner J, Ekstrom T, Jonsson D, Moller M. Asthma nurse practice improves outcomes and reduces costs in primary health care. Scandinavian Journal of Caring Sciences 2002;16:73-8.

45. Kamps AW, Roorda RJ, Kimpen JL, Overgoor-van de Groes AW, van Helsdingen-Peek LC, Brand PL. Impact of nurse-led outpatient management of children with asthma on healthcare resource utilisation and costs. European Respiratory Journal 2004;23:304-9.

46. Villagra VG, Ahmed T. Effectiveness of a disease management program for patients with diabetes. Health Affairs (Millwood) 2004;23:255-66.

47. Briggs AH, Ades AE, Price MJ. Probabilistic sensitivity analysis for decision trees with multiple branches: use of the Dirichlet distribution in a Bayesian framework. Medical Decision Making 2003;23:341-50.

48. Price MJ, Briggs AH. Development of an economic model to assess the cost effectiveness of asthma management strategies. Pharmacoeconomics 2002;20:183-94.

49. Saint-Pierre P, Combescure C, Daures JP, Godard P. The analysis of asthma control under a Markov assumption with use of covariates. Statistics in Medicine 2003;22:3755-70.

(Submitted: 14 May 2004 Final revised version received: 26 December 2004 Accepted: 6 January 2005)

1 Correspondence should be sent to Dr Jean Bousquet at this address (email: jean.bousquet@wanadoo.fr).

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BOOKS & ELECTRONIC MEDIA

Creating knowledge-based healthcare organizations

Chun Wei Choo

Professor, Faculty of Information Studies, University of Toronto, 140, St. George Street, Toronto, ON, M5S 3G6, Canada (email: cw.choo@utoronto.ca)

Editors: Nilmini Wickramasinghe, Jatinder N. D. Gupta, Sushil Sharma
Publisher: Idea Group Publishing, Hershey, PA, USA; 2005
ISBN: 1-59140-459-2; hardback; 388 pages; price US$ 84.95

According to the editors, the aim of this book is to increase awareness in the health sector of the need to embrace knowledge management. On the one hand, healthcare is facing the twin challenges of escalating costs and increasing demands for quality. On the other, there is growing recognition that healthcare organizations are knowledge-intensive and that they need to manage their information- and knowledge-bases more effectively. The central message of the book is that by harnessing knowledge management strategies, processes, tools and techniques, healthcare organizations can create greater value by delivering higher quality services more cost effectively.

The book comprises 24 chapters written by 51 authors. It is divided into four sections, which form a logical sequence that moves along the path from concept to practice. The first section (Knowledge management in the healthcare industry) consists of four chapters and begins by introducing knowledge management as a set of principles and processes, before going on to outline the forces in healthcare that are driving the need to embrace it. The second section (Approaches, frameworks and tools to create knowledge-based healthcare organizations), at nine chapters the longest, introduces an array of knowledge management tools and techniques, and discusses the impact of the internet, the use of data mining and knowledge discovery tools, medical records management, evidence-based medicine, and quality management. Section three (Key issues and concerns of various knowledge management implementationsevidence from practice) consists of six case studies that cover a wide range of healthcare organizations: a national hospital in Japan, telemedicine in New Zealand, a disability service in Australia, public hospitals in Ireland, and the pharmaceutical industry in India. The final section (Managing knowledge as an asset in healthcare organizations) has six chapters, three of which deal with measuring the contribution of knowledge management to business performance.

The main strength of the book is its international approach, covering as it does research and case studies from Asia, Australia, Brazil, India, Ireland, Japan, Netherlands, New Zealand, Republic of Korea, and USA. There is a clear emphasis on systems and process architectures, planning frameworks, and data security. Useful chapters examine the connection between knowledge management and evidence-based medicine, quality management and patient safety.

The book generally presents a sanguine view of knowledge management that highlights the power of technology to manage data and information efficiently. However, managing information is not the same as managing knowledge. Effective knowledge management is highly contingent on a large number of non-technological conditions: the culture of the healthcare organization, the norms and status of different professions, the structure of the healthcare industry, and the regulatory and policy environment. The book could have benefited from a thoughtful consideration of these issues.

Bearing in mind its strengths and limitations, the reader who is looking for a book on knowledge management that relates directly to the healthcare arena, and who is particularly interested in the application of information systems in its support, will be well served by this monograph.

^rND^1A01^nRobert^sBeaglehole ^rND^1A01^nRobert^sBeaglehole ^rND^1A01^nRobert^sBeaglehole

BOOKS & ELECTRONIC MEDIA

A history of epidemiologic methods and concepts

Robert Beaglehole

Director, Chronic Diseases and Health Promotion, World Health Organization, 1211 Geneva 27, Switzerland (email: beagleholer@who.int)

Editor: Alfredo Morabia
Publisher: Birkhäuser, Basel; 2004
ISBN: 3-7643-6818-7; softcover; 405 pages; price Swiss francs 130

This enthralling book is divided into two parts. The first part consists of a 125-page essay by Professor Morabia on the evolution of epidemiologic methods and concepts. This essay builds on and provides an introduction to the second part a series of papers on epidemiology, most of which have been published over the last few years in the journal Social and Preventive Medicine.

The extended introductory essay outlines the work of people who contributed to the development and elucidation of epidemiologic methods and concepts. This book is essentially an epidemiologist's view of the development of ideas. The broader task of explaining the development of epidemiology and its connections to society at large is the task of historians of science (see, for example, the book by Vinten-Johansen et al. Cholera, chloroform, and the science of medicine: a life of John Snow, published by Oxford University Press in 2003).

Morabia's essay is fascinating. He is one of the very few practising epidemiologists with a deep interest in the history of epidemiologic methods. The particular combination of his interests gives a special credibility to his essay, which describes how epidemiologic thinking has developed from the 18th century around two key ideas: concepts concerned with populations and group comparisons the hallmarks of modern epidemiology. Without these two simple ideas, and their integration, we would still be struggling to make causal judgments in epidemiology. And without a strong basis for assigning causality, epidemiology would be powerless. The contributions published in this book demonstrate that epidemiology is continuing to evolve. Morabia asks interesting questions, for example, was Hippocrates an epidemiologist (clearly not) and does the Book of Daniel in the Bible describe the first epidemiologic trial (again, no). He also gives a compelling argument for the late emergence of epidemiology most likely because it was dependent on the development of the idea of probability.

The papers in the second part deal with material that will be familiar to most epidemiologists and covers ground ranging from Snow and Farr to the history of study designs, bias, confounding and causality. Richard Doll writes lucidly on the history of cohort studies, and a study of recent textbooks illustrates how new epidemiology is as a discipline and how its fundamental ideas have evolved rapidly over the last half century.

The justification proposed for the book is the idea perhaps difficult to examine formally that epidemiologists will be better scientists if they are aware of the origins of the ideas they use and how these ideas have evolved. The editor proposes that the book will be of interest to epidemiology students. Certainly, it will resonate with many post-graduate students though I doubt whether the average participant in a basic epidemiology course will engage with more than a few of the ideas presented.

The ideas aired in this book are of more than just of academic interest. However, we need to understand much more about how these ideas have been put to good use. I encourage Morabia for his next project to go beyond methodological considerations and consider the applications of epidemiology to efforts to improve population health.

^rND^1A01^nRita^sLuthra ^rND^1A01^nRita^sLuthra ^rND^1A01^nRita^sLuthra

LETTERS

Internet health learning to improve women's health

Rita Luthra

President, Women's Health and Education Center, 300 Stafford Street; Suite 265, Springfield, MA 01104, USA (email: rita@womenshealthsection.com)

Editor I wish to congratulate S. Yunkap Kwankam on his article. As he rightly says, "e-Health systems can improve access to information, thus increasing awareness of what is known in the health sciences, while selective dissemination by electronic means can facilitate targeting of information on those who either request it or are most likely to use it" (1).

The health and status of women is a very complex and a challenging issue for developing and industrialized countries alike. Women face enormous obstacles prejudice, ostracism, domestic violence, poverty, hunger and virtually no access to medical care and life-saving medicines.

Knowledge and understanding are preconditions for action at all levels of the health-care and other systems. Skilled attendants mean successful outcomes and education is for life. Internet has connected the world, and e-learning projects in obstetrics and gynaecology between the United States and developing countries are of mutual benefit and foster mutual respect. The United States is a vast multicultural society, and providing quality care to diverse populations requires much more than translating a foreign language. We should be willing to learn where each patient is "coming from", taking into account how culture, customs and community pressures affect her decision-making processes.

Of all the health statistics monitored by WHO, maternal mortality shows the largest discrepancy between developed and developing countries. Every day at least 1600 women die from complications of pregnancy and childbirth: 90% of these deaths occur in the developing countries.

Internet classrooms are the most cost-effective way to provide continuing medical education to the developing countries. The Women's Health and Education Center launched an e-learning project in association with the Department of Public Information of the United Nations on 24 October 2002 (http://www.WomensHealthSection.com). Two years later it had reached more than 100 countries and it is proving to be an excellent resource in the education of health-care providers and policy-makers who are working for Safe Motherhood. Connecting to the healthcare providers and getting the message across are essential.

The syllabus of our project is designed to stress common, everyday health-care issues in women's health. The text is divided into five sections to give a comprehensive overview of women's health-care: violence against women, obstetrics, gynaecology, uro/gynaecology, and health-care policies and women's health. A sub-section on obstetric fistula provides insight into this devastating problem in developing countries. We hope the sections will serve both as a comprehensive review and a reference to facilitate understanding of the disease process. Most of all, however, we hope that the contents will motivate future research that will further enhance the understanding of reproductive health.

Even though the main focus is on Safe Motherhood, sections on violence against women and health-care policies are included to assist the development of effective strategies for action. We believe meaningful programmes can be developed to reduce maternal mortality and morbidity in the developing countries.

Translation into different languages is definitely an important step to improve better understanding of the medical literature, and will help the health-care providers and policy-makers to express their needs and build networks. The languages chosen for our web site are those of the United Nations: Arabic, Chinese, English, French, Russian and Spanish. We believe this availability of medical scripts in cyberspace will improve people's relationship with the new medium and their ability to tap its potential.

Education is the best gift in life both to give and to receive. The developing countries and industrialized countries can both learn a great deal from each other's experiences with various social and health-care projects and programmes. In the United States, fascination with the technology seems to be endless. The development of technology has certainly enhanced our ability to diagnose and treat patients, to the extent that we almost defy death. The developing countries have done good job in many areas with limited technology and clinical medicine.

Investing in wireless Internet technology is the way forward to tackle maternal mortality and morbidity in the developing countries. Imagine sitting at home or in an office in the United States and teaching obstetrics, gynaecology and uro/gynaecology to the developing countries and learning from their perspectives too. By interacting with different cultures we will be able to understand different customs and learn to respect the diversity.

E-learning is the most cost-effective way of transmitting evidence-based medicine to the developing countries. Continuing medical education is a requirement in the United States, Canada and the United Kingdom for the renewal of medical licences, and this gives an incentive to stay up to date on medical advances. Continuing medical education regulations for health-care providers have been proposed in legislation in India, and many other developing countries could follow suit.

Continuing medical education is a lifetime commitment requiring knowledge of current trends and developments in the science, technology and economics of health care, and thereby improving the quality of health care. The convenience of provider-directed independent study activities allows health-care professionals to reach the learning goals that must be incorporated into their demanding professional schedules.

Competing interests: none declared.

References

1. Kwankam SY. What e-Health can offer. Bulletin of the World Health Organization2004;82:800-2.

^rND^1A01^nNiyi^sAwofeso ^rND^1A01^nNiyi^sAwofeso ^rND^1A01^nNiyi^sAwofeso

LETTERS

The place of leprosy in the controleliminationeradication spectrum

Niyi Awofeso

Associate Professor, School of Public Health and Community Medicine, University of New South Wales, Sydney 2052, Australia (email: niyi.awofeso@justicehealth.nsw.gov.au)

Editor I would like to expand on Lockwood & Suneetha's reflections on the leprosy elimination campaign (1), and in particular their statement that "leprosy is perhaps more appropriately classed as a chronic stable disease rather than as an acute infectious disease responsive to elimination strategies", by using the controleliminationeradication (CEE) paradigm that has served public health workers and surveillance experts so well in the fight against communicable diseases since the late 19th century (2).

Infectious disease "elimination" commonly refers to reducing the number of cases of disease to a small and routinely manageable number. Thus, prevalence trend is a key yardstick in the CEE paradigm. When leprosy elimination campaigns were put in place in the 1990s, their primary goals were to implement enhanced surveillance activities in order to detect leprosy cases promptly and to treat them immediately with multidrug therapy (3). Between 1985 and 2002, global leprosy prevalence fell by about 95% (1). In May 2001, the World Health Assembly affirmed that "the overall target, set ten years ago, for the global elimination of leprosy as a public health problem has been attained" (4).

"Control" is usually the first approach to cope with the deleterious effects of intractable infectious diseases such as tuberculosis and syphilis. When the prevalence and adverse effects are curtailed, the focus normally shifts from control to elimination. For example, as the prevalence of Chagas disease continues to fall in Central America, the focus has shifted from disease control to disease elimination, through vector control activities and the screening of blood banks (5).

Smallpox is probably the only human disease so far that has reached the "eradication" end of the spectrum (no cases reported since 1979), though dracunculiasis (guinea-worm disease) which, like leprosy, is a chronic stable disease and poliomyelitis are also inching very close to being eradicated. For instance, there are currently less than 800 incident cases of polio worldwide, and the formidable infrastructure for polio eradication makes it more likely than ever that the disease will be eradicated during this decade (6). Interestingly, erstwhile polio researchers expressed serious doubts concerning the feasibility of poliomyelitis elimination or eradication about a century ago, when poliovirus microbiology and vaccination were less well understood (7).

It is noteworthy that diseases that have progressed steadily from the control to the eradication ends of the spectrum are invariably those whose microbiology has been well delineated and for which effective control and treatment measures to interrupt transmission are available. The microbiology of leprosy is not yet fully elucidated, and it appears unlikely that multidrug therapy alone would prevent leprosy transmission (1). Given these gaps in current knowledge concerning microbiology and therapy, it is not surprising that the elimination stage appears to be the dead end for efforts to reduce the scourge of leprosy. While it would be counter-intuitive to go back to the control stage of the paradigm, given the tremendous progress made in case detection and treatment (especially since the introduction of multidrug therapy in the 1980s), it is also clear that unless we can bridge the gaps in our knowledge of leprosy microbiology and transmission mapping, leprosy elimination is unlikely to progress to leprosy eradication.

Rather than table a World Health Assembly resolution that leprosy has not been eliminated, as reportedly suggested by some evaluators of the Global Alliance for the Elimination of Leprosy (1, 8), it might be more productive to work towards overcoming our knowledge gaps with regard to leprosy microbiology and therapy. Unless extraordinary resources are provided for clinical and epidemiological research, leprosy will remain a disease that is eliminated but is far from eradicated. Such an approach might in fact stimulate interest among a new generation of researchers, and generate research funding from donors that hitherto appear reluctant to support leprosy research.

Competing interests: none declared.

References

1. Lockwood DNJ, Sunetha S. Leprosy: too complex a disease for a simple elimination paradigm. Bulletin of the World Health Organization 2005;83:230-5.

2. Dowdle WR. The principles of disease elimination and eradication. Bulletin of the World Health Organization 1998;76(suppl.2):22-5.

3. WHO Action Programme for the Elimination of Leprosy. Guidelines for carrying out leprosy elimination campaigns 1996. Leprosy Review 1999;70:408-27.

4. Leprosy: global target attained. Geneva: World Health Organization; 2001. World Health Assembly Press Release WHA54/2, 16 May 2001. Available from: http://www.who.int/inf- pr-2001/en/pr2001WHA-2.html

5. Schofield CJ, Dias JC. The Southern Cone initiative against Chagas disease. Advances in Parasitology 1999;42:1-27.

6. Aylward RB, Linkins J. Polio eradication: mobilizing and managing human resources. Bulletin of the World Health Organization 83;268-73.

7. Benison S. Polio research in the United States: appraisal and lessons. In: Holton G, editor. The 20th century sciences studies in the biography of ideas. New York: WW Norton & Company; 1972:308-43.

8. Baohong JI. Comments on the report entitled "Independent evaluation of the Global Alliance for the Elimination of Leprosy". Leprosy Review 2004;75:217-20.

^rND^1A01^nKnut^sLönnroth^rND^1A01^nMukund^sUplekar ^rND^1A01^nKnut^sLönnroth^rND^1A01^nMukund^sUplekar ^rND^1A01^nKnut^sLnnroth^rND^1A01^nMukund^sUplekar

LETTERS

Invest in breaking the barriers of publicprivate collaboration for improved tuberculosis care

Knut Lönnroth¹; Mukund Uplekar

TB Strategy and Operations, Stop TB Department, World Health Organization, 1211 Geneva 27, Switzerland (email: lonnrothk@who.int)

Editor Mahendradhata & Utarini rightly call for a an urgent move from feasibility studies of publicprivate collaboration in tuberculosis (TB) control to studies that analyse success factors as well as the cost and cost-effectiveness of such initiatives (1). WHO is currently coordinating a number of operational research initiatives that focus on these issues.

In the August 2004 issue of the Bulletin, we published a study on success factors for publicprivate collaboration in TB control (2). That analysis was based on project evaluations of four initiatives in three countries. We are continuously updating this analysis based on a rapidly growing body of data from more than 40 ongoing projects in 14 countries. A policy framework and tools to help implementation have been developed based on field experiences and operational research. Information about WHO's work on private sector involvement in TB control can be found on the web site: http://www.who.int/tb/dots/ppm.

Mahendradhata & Utarini highlight the fact that publicprivate collaboration for improved TB control takes place in a context of constrained resources and competing interests. Our analysis suggests that government investment is indeed crucial in order to ensure technical capacity-building in the private sector, managerial capacity-building in the public sector, improved supervision and quality control of private providers, and improved surveillance. Public funding is also needed in order to secure a supply of drugs and consumables free of charge to TB patients attending private clinics. While additional investments will be required, cost-effectiveness analysis of two collaborative projects in India has demonstrated that the amounts of such investments would be comparable, on a cost per successfully treated case basis, to those required by the public sector (3). From a societal perspective, a significant added value would be a substantial reduction in the financial burden on patients and, potentially, early detection and reduction in transmission of TB.

From documented experiences, what do we already know about why partnerships work? As expected, the determinants of success are precisely the factors that help to counter some of the well-known barriers to collaboration (4). First, a genuine commitment on the part of the public sector demonstrating that it is indeed interested in working with private providers; second, justifiable additional investments human and financial to help build the collaboration and contribute further to TB control; third, a proper situational analysis to develop a locally appropriate task-mix for public and private providers; fourth, orientation and training of both public and private providers to prepare them to work together; and finally, a built-in monitoring and evaluation system to continue to measure the benefits and to improve upon the collaboration (2, 5).

For Mahendradhata & Utarini's own project, if they intend to apply first what they mentioned first the strategy of strengthening regulatory structures then a word of caution is called for. Regulation of private providers is indeed crucial and must be dealt with. To begin with a heavy emphasis on "regulating" providers, however, could turn the project into a non-starter. Experience shows that in publicprivate partnership building, when to employ a strategy is as important as the strategy itself. This and similar potential stumbling blocks could be avoided if private providers are involved in the process right from the first step of planning an intervention and, more importantly, in a spirit of partnership.

Competing interests: The authors work with the PublicPrivate Mix for DOTS Initiative in the Stop TB Department at WHO.

References

1. Mahendradhata Y, Utarini A. Publicprivate partnership for tuberculosis control: the bill please? Bulletin of the World Health Organization 2005;83:78.

2. Lönnroth K, Uplekar M, Arora VK, Juvekar S, Lan NTN, Mvaniki D, et al. Publicprivate mix for improved TB control what makes it work? Bulletin of the World Health Organization 2004;82:580-6.

3. Cost and cost-effectiveness of Public-Private Mix DOTS: evidence from two pilot projects in India. Geneva: World Health Organization; 2004. WHO document WHO/HTM/TB/2004.337.

4. Involving private practitioners in tuberculosis control: issues, interventions, and emerging policy framework. Geneva: World Health Organization; 2001. WHO document WHO/CDS/TB/2001.285.

5. Practical tools for involvement of private providers in TB control A guide for NTP managers. Geneva: World Health Organization; 2003. WHO document WHO/CDS/TB/2003.325.

1 Correspondence should be sent to this author.

^rND^1A01^nStephanie A.^sJones^rND^1A02 A03^nGayle G.^sSherman^rND^1A04^nAshraf H.^sCoovadia ^rND^1A01^nStephanie A.^sJones^rND^1A02 A03^nGayle G.^sSherman^rND^1A04^nAshraf H.^sCoovadia ^rND^1A01^nStephanie A^sJones^rND^1A02 A03^nGayle G^sSherman^rND^1A04^nAshraf H^sCoovadia

LETTERS

Can clinical algorithms deliver an accurate diagnosis of HIV infection in infancy?

Stephanie A. Jones^I,1; Gayle G. Sherman^II; Ashraf H. Coovadia^III

^IMedical Officer, Wits Paediatric HIV Working Group, PO Box 2086, Fourways, Johannesburg 2055, South Africa (email: stephanie.jones@hivsa.com)
^IIAssociate Professor, Department of Molecular Medicine & Heamatology, University of the Witwatersrand and National Health Laboratory Services, Johannesburg, South Africa
^IIIPaediatrician, Coronation Hospital, Wits Paediatric HIV Working Group, Johannesburg, South Africa

Editor The Integrated Management of Childhood Illness (IMCI) guidelines established clinical criteria to identify children with suspected HIV infection for HIV testing and specific management. In an article published in the Bulletin, based on a study conducted in South Africa, Horwood et al. report that they have fine-tuned these criteria into a clinical algorithm (1). This algorithm has been incorporated into the 2003 edition of the South African IMCI guidelines to maximize identification of HIV infected children (1, 2). Horwood et al.'s study clinically assessed 690 hospital outpatients, aged 259 months, in an HIV prevalence setting of 28.7%. In the absence of screening questions, the clinical algorithm was applied and yielded a sensitivity of 70%, specificity of 80% and a positive predictive value (PPV) of 59%. The validity of the algorithm for the 226 infants (211 months), 38% of whom were infected, did not to differ from that for the other age categories (1).Validation of the clinical algorithm in different settings was invited (1).

Vertically exposed infants in prevention-of-mother-to-child transmission (PMTCT) programmes in low-resource settings rely on clinical assessments for HIV diagnosis since infants are first tested at 12 months of age using an HIV enzyme-linked immunosorbent assay (ELISA). The HIV prevalence among infants will vary according to the availability of PMTCT services and the mode of infant feeding. We carried out a study to establish an affordable and accurate diagnostic protocol for HIV using a cohort of 301 infants attending a PMTCT clinic at Coronation Women and Children's Hospital, a secondary- level hospital in Johannesburg, South Africa (3). At 12 months of age, the infant's true HIV-infection status was determined using polymerase chain reaction testing according to the Centers for Disease Control and Prevention guidelines, in conjunction with clinical assessments (4). In a predominantly exclusively formula-fed population, 26 patients (8.7%) were HIV positive (3). At the visits at 6 weeks and at 3, 7 and 12 months of age, 18 different doctors experienced in local paediatric HIV care and blinded to the HIV test results prospectively diagnosed the infant's HIV infection status based on clinical findings. Two-thirds of all clinical examinations were performed by paediatricians. The clinical findings were recorded on a structured data collection tool that concentrated on clinical features derived from Center for Disease Control (CDC) clinical guidelines (i.e., recurrent infections, weight gain, candidiasis, lymphadenopathy, hepatosplenomegaly) (4). The number of HIV-infected infants who were correctly clinically diagnosed in our study increased with age from 56% at 6 weeks of age to 93% at 12 months of age.

The performance of the IMCI algorithm in our study population was retrospectively assessed by applying our source data to the South African 2003 IMCI clinical algorithm which consists of asking, looking and feeling for eight features of symptomatic HIV without the screening questions (5).

The disturbing finding was that the algorithm would have detected only 17% of HIV-infected infants at 6 weeks of age. Even though the detection rate improved to 50% for infants aged 12 months, this was still much lower than the rate of 70 % reported by Horwood et al. (1). Retrospective application of the IMCI algorithm to clinical data collected by highly skilled personnel therefore yielded particularly poor sensitivity in detecting HIV infection throughout infancy.

A long-term prospective study in Rwanda has documented that HIV-infected children in Africa develop early morbidity and mortality (6). In our cohort, all 15 surviving HIV-infected infants available for assessment at 12 months of age were symptomatic and required specific medical interventions, e.g. antifungal treatment for oral thrush. Despite this clinical scenario, eight (53%) of the 12-month-olds would not have been detected by the IMCI algorithm. The high early mortality rate of HIV-infected infants is a further concern, particularly with the increasing availability of antiretroviral therapy. Of the 10 HIV-infected infants who died before their first birthday, 5 (50%) would have remained undiagnosed by the IMCI algorithm. The clinical assessments in our study missed 2 (20%) of these children. Like Horwood et al., we noted that the higher sensitivity of the doctors' clinical assessments was often attributable to the detection of hepatosplenomegaly, which is not included in the IMCI algorithm (1).

Clinical diagnosis of HIV infection in infancy remains a challenge. Additional prospective assessments of the IMCI clinical algorithm in vertically exposed infants in PMTCT settings with different HIV prevalence are required. It is a cause for concern that in our PMTCT setting the IMCI algorithm used by highly skilled clinical practitioners only identified approximately half of the infants experiencing HIV-related mortality and morbidity at 12 months of age. In an era of expanding antiretroviral scale-up programmes, clinical assessment remains an unacceptably insensitive diagnostic tool for ensuring that HIV-infected infants access care. A more pragmatic approach may be to invest in assessment of affordable, simple methods of testing for early diagnosis of infants rather than relying on clinical skills alone.

Competing interests: none declared.

References

1. Horwood C, Liebeschuetz S, Blaauw D, Cassol S, Qazi S. Diagnosis of paediatric HIV infection in a primary health care setting with a clinical algorithm. Bulletin of the World Health Organization 2003;81:858-66

2. World Health Organization, Regional Office for Africa. Report on the Workshop on Adaptation of IMCI Guidelines to include HIV/AIDS. Harare 18-23 June 2001.Available from: www.who.int/child-adolescenthealth/New_Publications/ HIV/report_HIV_Harare.htm (accessed 26 August 2004)

3. Sherman GG, Jones SA, Coovadia AH, Urban MF, Bolton KD. PMTCT from research to reality results from a routine service. South African Medical Journal 2004;94:289-92.

4. Centers for Disease Control. 1994 revised classification system for human immunodeficiency virus infection in children less than 13 years of age. Morbidity and Mortality Weekly Report 1994;(No. RR-12):1-10.

5. Integrated Management of Childhood Illness. South African Edition. South African Department of Health, Pretoria, South Africa. October 2003.

6. Spira R, Lepage P, Msellati P, Van der Perre P, Leroy V, Simonon A, et al. Natural history of human immunodeficiency virus type 1 infection in children: a five-year prospective study in Rwanda. Pediatrics 1999;104:e56.

1 Correspondence should be sent to this author.

^rND^1A01^nJean^sBousquet^rND^1A01^nPhilippe J.^sBousquet^rND^1A01^nPhilippe^sGodard^rND^1A02^nJean-Pierre^sDaures ^rND^1A01^nJean^sBousquet^rND^1A01^nPhilippe J.^sBousquet^rND^1A01^nPhilippe^sGodard^rND^1A02^nJean-Pierre^sDaures ^rND^1A01^nJean^sBousquet^rND^1A01^nPhilippe J^sBousquet^rND^1A01^nPhilippe^sGodard^rND^1A02^nJean-Pierre^sDaures

PUBLIC HEALTH REVIEWS

The public health implications of asthma

Incidences de l'asthme sur la santé publique

Repercusión del asma en la salud pública

Jean Bousquet^I,1; Philippe J. Bousquet^I; Philippe Godard^I; Jean-Pierre Daures^II

^IClinique des Maladies Respiratoires, Hôpital Arnaud de Villeneuve, CHU Montpellier, 34295- Montpellier-Cedex 05, France
^IIDépartement d'Information Médicale, Hôpital Gaston Doumerge, Nîmes, France

ABSTRACT

Asthma is a very common chronic disease that occurs in all age groups and is the focus of various clinical and public health interventions. Both morbidity and mortality from asthma are significant. The number of disability-adjusted life years (DALYs) lost due to asthma worldwide is similar to that for diabetes, liver cirrhosis and schizophrenia. Asthma management plans have, however, reduced mortality and severity in countries where they have been applied. Several barriers reduce the availability, affordability, dissemination and efficacy of optimal asthma management plans in both developed and developing countries. The workplace environment contributes significantly to the general burden of asthma. Patients with occupational asthma have higher rates of hospitalization and mortality than healthy workers. The surveillance of asthma as part of a global WHO programme is essential. The economic cost of asthma is considerable both in terms of direct medical costs (such as hospital admissions and the cost of pharmaceuticals) and indirect medical costs (such as time lost from work and premature death). Direct costs are significant in most countries. In order to reduce costs and improve quality of care, employers and health plans are exploring more precisely targeted ways of controlling rapidly rising health costs. Poor control of asthma symptoms is a major issue that can result in adverse clinical and economic outcomes. A model of asthma costs is needed to aid attempts to reduce them while permitting optimal management of the disease. This paper presents a discussion of the burden of asthma and its socioeconomic implications and proposes a model to predict the costs incurred by the disease.

Keywords: Asthma/epidemiology/therapy/economics; Workplace; Disease management; Epidemiologic surveillance; Health care costs; Cost of illness; World Health Organization; Socioeconomic factors; Forecasting/methods; Models, Theoretical (source: MeSH, NLM).

RÉSUMÉ

L'asthme est une maladie chronique très courante dans toutes les tranches d'âge, qui fait l'objet de diverses interventions cliniques et actions de santé publique. La mortalité comme la morbidité dues à l'asthme sont importantes. A l'échelle planétaire, le nombre d'années de vie corrigées de l'incapacité perdues à cause de l'asthme est similaire à celui résultant des diabètes, de la cirrhose du foie ou de la schizophrénie. Des programmes de prise en charge de l'asthme ont néanmoins permis de réduire la mortalité liée à l'asthme et la gravité de cette maladie dans les pays où ils ont été mis en uvre. Plusieurs obstacles s'opposent à la disponibilité, à l'accessibilité économique, à la diffusion et à l'efficacité de programmes optimaux de prise en charge de l'asthme, aussi bien dans les pays développés que dans les pays en développement. L'environnement de travail contribue pour une part importante à la charge générale d'asthme. Les malades atteints d'asthme professionnel présentent des taux d'hospitalisation et de mortalité plus élevés que les travailleurs en bonne santé. Il est absolument nécessaire que la surveillance de l'asthme s'intègre dans un programme mondial de l'OMS. Les coûts économiques de cette maladie sont considérables, tant par leur composante médicale directe (séjours hospitaliers et médicaments, par exemple), que par leur composante médicale indirecte (absences au travail et décès prématuré, par exemple). Les coûts directs sont conséquents dans la plupart des pays. En vue de réduire ces coûts et d'améliorer la qualité des soins, les employeurs et les responsables de programmes sanitaires étudient des moyens mieux ciblés pour maîtriser les coûts de santé en augmentation rapide. La mauvaise maîtrise des symptômes de l'asthme est un problème majeur, pouvant avoir des conséquences préjudiciables sur le plan clinique et économique. Il est nécessaire de disposer d'un modèle des coûts de l'asthme permettant d'étayer les tentatives pour les réduire et d'optimiser la prise en charge de la maladie. Le présent article décrit la charge que fait peser l'asthme sur la santé publique et les incidences socioéconomiques de cette maladie.

Mots clés: Asthme/épidémiologie/thérapeutique/économie; Poste travail; Gestion maladie; Surveillance épidémiologique; Coût soins médicaux; Coût maladie; Organisation mondiale de la Santé; Facteur socioéconomique; Prévision/méthodes; Modèle théorique (source: MeSH, INSERM).

RESUMEN

El asma es una enfermedad crónica muy común que afecta a todos los grupos de edad y constituye el objetivo de diversas intervenciones clínicas y de salud pública. Tanto la morbilidad como la mortalidad por asma son importantes. El número de años de vida ajustados en función de la discapacidad (AVAD) perdidos como consecuencia del asma en todo el mundo es similar al de la diabetes, la cirrosis hepática y la esquizofrenia. Sin embargo, los planes de tratamiento del asma han reducido la mortalidad asociada y su gravedad en los países donde se han aplicado. Hay varios obstáculos que reducen la disponibilidad, la asequibilidad, la difusión y la eficacia de los planes de tratamiento óptimo del asma tanto en los países desarrollados como en los países en desarrollo. El entorno de trabajo contribuye sensiblemente a la carga general de asma. Los pacientes con asma ocupacional tienen mayores tasas de hospitalización y mortalidad que los trabajadores sanos. La vigilancia del asma como parte de un programa mundial de la OMS es una necesidad esencial. El costo económico del asma es considerable, y ello incluye tanto los costos médicos directos (por ejemplo los de los ingresos hospitalarios y las preparaciones farmacéuticas) como los costos médicos indirectos (entre ellos las horas de trabajo perdidas y las muertes prematuras). Los costos directos son notables en la mayoría de los países. A fin de reducir los costos y de mejorar la calidad de la atención, los empleadores y los planes de salud están estudiando mecanismos más precisos para controlar unos costos sanitarios rápidamente crecientes. El control deficiente de los síntomas del asma constituye un serio problema que puede tener consecuencias clínicas y económicas adversas. Hace falta un modelo de los costos asociados al asma para coadyuvar a las iniciativas encaminadas a reducirlos sin dejar de aplicar un tratamiento óptimo contra la enfermedad. En este artículo se analizan la carga de asma y sus repercusiones socioeconómicas y se propone un modelo para predecir los costos que acarrea la enfermedad.

Palabras clave: Asma/epidemiología/terapia/economía; Lugar de trabajo; Manejo de la enfermedad; Vigilancia epidemiológica; Costos de la atención en salud; Costo de la enfermedad; Organización Mundial de la Salud; Factores socioeconómicos; Predicción/métodos; Modelos teóricos (fuente: DeCS, BIREME).

Introduction

Health economics is receiving more attention as decision-makers including purchasers, physicians and patients seek a more comprehensive understanding of the impact of adopting new health care strategies in developed and developing countries. Formal economic evaluation is playing an increasingly important role in health care decision-making, including that related to asthma (1).

Asthma, a chronic disease that affects both children and adults, has been the focus of clinical and public health interventions during recent years. In the present paper we discuss firstly the burden of asthma including the trends in prevalence, severity, mortality and disability-adjusted life years (DALYs) as well as the barriers to its optimal management. Secondly, the role of the workplace environment as a contributor to the general burden of asthma will be examined. Thirdly, surveillance of asthma as part of the WHO noncommunicable disease (NCD) surveillance programme for disease management will be examined. Finally, we review the direct and indirect costs of asthma and how they can be optimized and predicted.

Burden of asthma

Importance of noncommunicable diseases in developed and developing countries

There is no doubt that, for the next 1020 years, communicable diseases will remain the predominant health problem for the populations of many developing countries. Worldwide, NCDs represent 43% of the burden of disease and this is expected to increase in the future, particularly in developing countries (2). There is already evidence that the prevalence of certain NCDs, such as diabetes, asthma, chronic obstructive pulmonary disease (COPD), epilepsy and hypertension, is increasing rapidly in some low-income countries (3).

In developing countries, chronic respiratory diseases (CRDs) represent a challenge to public health because of their increasing frequency and severity, and the projected trends and economic impact (4, 5). Health care planners are also faced with the consequence of a dramatic increase in tobacco use and must establish priorities for the allocation of limited resources.

Trends in prevalence

Asthma is one of the most common chronic diseases in the world. It is estimated that around 300 million people in the world currently have asthma (6). In the global burden of asthma report of the Global Initiative for Asthma, the prevalence of asthma in different countries has been considered to range from 1% to 18% of the population (see Fig. 1; web version only, available: http://www.who.int/bulletin) (6).

The prevalence of asthma increases as communities adopt modern lifestyles and become urbanized (5). With the proportion of the world's population living in urban areas projected to increase from 45% to 59% in 2025, there is likely to be a marked increase in the number of people with asthma worldwide over the next two decades. It is estimated that there may be an additional 100 million people with asthma by 2025 (6).

However, the prevalence of asthma and allergy may decrease in children in some countries with a high prevalence of the disease (7). In some countries, an increasing prevalence of allergic rhinitis, but not asthma has been observed (8). It is therefore possible that the increase in the asthma epidemic is coming to an end in some countries (Fig. 2).

Trends in severity and mortality

Although the information on asthma mortality is unreliable in many countries, it is estimated that asthma accounts for about 250 000 deaths per year worldwide (6). There are large differences between countries, and, unexpectedly, the rate of asthma deaths does not parallel prevalence (Fig. 1). Many of the deaths are preventable, being due to suboptimal long-term medical care and delay in obtaining help during the final attack. The countries with the highest death rates are those in which controller therapy is not available (6). In the USA, death rates have increased within the past 20 years, but only in poor minority groups whose access to health care is inadequate (9). In many countries, deaths due to asthma have declined recently as a result of better management.

The number of hospitalizations of patients with asthma is another measure of asthma severity, but cannot be obtained in most developing countries (10). In countries where national asthma management plans have been implemented, hospitalization rates have decreased (11).

Childhood asthma accounts for many lost school days and may deprive the affected children of both academic achievement and social interaction.

Disability-adjusted life years

Collecting information on non-fatal health outcomes of disease and injury has been largely neglected in health planning because of the conceptual and definitional complexity of measuring morbidity and disability in populations. DALYs, which were launched by the World Bank and backed by WHO as a measure of the Global Burden of Disease (GBD), combine morbidity and mortality (12). The number of DALYs currently lost due to asthma worldwide has been estimated to be about 15 million per year (6). Worldwide, asthma accounts for around 1% of all DALYs lost, which reflects the high prevalence and severity of the disease. The number of DALYs lost due to asthma is similar to that for diabetes, cirrhosis of the liver and schizophrenia.

Barriers to successful management

Several barriers have been shown to reduce the availability, affordability, dissemination and efficacy of optimal asthma therapies (5, 6).

Economic and generic barriers. These include poverty, poor education, illiteracy, lack of sanitation and poor infrastructure (13).

Cultural barriers. These include multiplicity of languages, as well as religious and cultural beliefs (13).

Environmental barriers. These include tobacco smoking, indoor and outdoor pollution, occupational exposure and nutrition. Poor nutrition is common in developing countries, whereas obesity and overweight are increasing in high- and middle-income countries as well as in the urban areas of low-income countries.

Drug and device availability and accessibility. In many countries, there is still poor accessibility to drugs despite the Bamako Initiative launched over 15 years ago (14). There is also a lack of resources for the diagnosis of CRD in low-income countries. For CRD programmes to be effective, producers of high-quality generic drugs will need to be identified, and medications added to national lists of essential drugs and included in procurement procedures (15). The members of the World Trade Organization (WTO) issued a historic Ministerial Declaration in Doha in 2002 to protect public health and promote access to medicines for all (16).

Traditional medicine. In many countries, alternative and complementary medicine is commonly used. In developing countries with many traditional healers, traditional medicine is extremely important and may often be the only available therapy. Treatment with traditional medicines is usually the first step in the management of diseases because of beliefs of patients and taboos, the inaccessibility of health care and high drug costs. In many places, traditional and modern medicine have tended to work in tandem. Research is needed to assess the efficacy of traditional medicine alone or in combination with effective drugs in the treatment of persistent asthma. If efficacy is demonstrated, cost-effectiveness studies are critical and should be initiated. Because the cost of drugs is often high, the use of appropriate traditional medicine was promoted at the fifty-fifth World Health Assembly. Unfortunately, there have as yet been no large controlled studies on the efficacy of traditional remedies in treating CRD.

Large differences in health care systems. Differences exist even within high-income countries and are far more marked between middle- and low-income countries.

Gaps, relevance and the integration of different guidelines in developing countries. Most guidelines for CRD have been proposed for countries where all drugs are available and affordable. Moreover, they do not necessarily take into account economic and generic barriers, and are difficult to apply to the majority of the population of low-income countries. They therefore need to be adapted to the local conditions. For example, guidelines for asthma management in developing countries were proposed in the International Union for Tuberculosis and Lung Diseases (IUATLD) asthma guide (17).

The lack of symptom-based guidelines. There is a lack of symptom-based guidelines that can be applied, rather than disease-based approaches, to the management of all CRDs. The WHO practical approach to lung health (www.who.int/gtb/policyrd/PAL/assessments.htm) is a syndromic approach to the management of patients who attend primary health care facilities for respiratory symptoms. It targets the various health workers, nurses, doctors and managers in primary health care settings with successful tuberculosis (TB) control programmes in low- and middle-income countries (18). Such a symptom-based approach also needs to be developed and implemented in high-income countries using tools adapted to the local situation and health system.

Occupational asthma

Evidence is accumulating that the workplace environment contributes significantly to the general burden of asthma (19, 20), but information on prevalence is difficult to obtain in most countries. In both developed and developing countries, occupational asthma represents a public health problem with economic implications (5). If workers are removed from exposure to the trigger substance as soon as they start to develop symptoms, they are likely to make a complete recovery. If exposure continues, however, symptoms are likely to become increasingly severe and may persist after exposure to the offending substance has ended.

Patients with occupational asthma have higher rates of hospitalization and mortality than healthy workers (21).

WHO noncommunicable disease surveillance programme

Effective prevention strategies for NCDs do exist. However, they require specific data on risk factors so that priorities can be set appropriately and targeted interventions developed and monitored. The WHO Global NCD Risk Factor Surveillance Initiative responds directly to this need. This project is managed by the Cross Cluster Surveillance Initiative of the Noncommunicable Diseases and Mental Health cluster (ncd_surveillance@who.int).

The project will be considered successful, if, at the end of a 5-year period the following targets have been met.

The first global assessment of country-specific burden, patterns and trends in major risk factors and identification of the gaps to be filled has been published.

Half of the WHO Member States have conducted at least one survey following the WHO Global NCD Risk Factor Surveillance strategy.

The awareness of the potential usefulness of surveillance for NCD risk factors in public health decision-making is raised.

Other surveillance programmes have also been launched. The Centers for Disease Control and Prevalence (CDC) outlined a strategy to improve the timeliness and geographical specificity of asthma surveillance as part of a comprehensive public health approach to asthma surveillance.

Socioeconomic implications

Direct and indirect costs

The economic cost of asthma is considerable both in terms of direct medical costs (such as hospital admissions and the cost of pharmaceuticals) and indirect medical costs (such as time lost from work and premature death) (6, 22). Direct costs represent approximately 13% of total medical expenditures in most countries. In 1998, the economic burden of asthma in the United States was estimated to be US$ 12.7 billion. Indirect costs account for over 50% of the total costs. Asthma-related costs are largely attributable to pharmaceuticals, hospitalizations and visits to emergency departments as well as days of work lost (23). Intangible costs such as those incurred by a low quality of life are very difficult to measure. Both the direct and indirect costs of asthma to an employer are substantial (23).

The costs of asthma depend on severity of disease (24, 25) and the extent to which exacerbations are avoided or at least controlled (26). Patients with difficult-to-treat or suboptimally controlled asthma consume a disproportionate share of asthma health care resources (27).

Other factors that increase the costs related to asthma have been highlighted, for example, exposure to second-hand tobacco smoke increases health care utilization in children with asthma (28). Comorbidities such as allergic rhinitis increase asthma costs. In some studies, children of low socioeconomic status were likely to require more resources because of their asthma (29, 30).

Underdiagnosed asthma is common. Many children with underdiagnosed asthma miss school and require emergency department visits, although those with a current diagnosis of asthma report more utilization of resources (31).

In developing countries, childhood asthma has significant adverse effects on the child's daily activities, schooling, family life and finances. In India, the median monthly expenditure on a child's medication was reported to be rupees 333, i.e. about one third of monthly per capita income (32).

Attempts to improve patient care and reduce costs

In order to reduce costs and improve quality of care, employers and health plans are exploring more precisely targeted ways to control rapidly rising health costs. Disease management programmes, which focus on patients with chronic conditions such as asthma and diabetes, are gaining importance (33). Even though the chronic care model has the potential to improve care and reduce costs, several obstacles still hinder its widespread adoption.

National disease management plans for asthma now exist in many countries (11) and some have resulted in a dramatic reduction in mortality and severity, thereby reducing costs (11). For example, the French Government issued an initiative on 28 January 2002 for better management and prevention of asthma (http://www.sante.gouv.fr). This plan proposes several activities for the next 5 years: prevention at school, better care and management in emergency units, development of asthma education, consideration of occupational asthma and the proposal of guidelines for follow-up. The effectiveness of a multicomponent self-management programme in those at risk was demonstrated in school-aged children with asthma (34).

Poor control of asthma symptoms is a major issue that can lead to adverse clinical and economic outcomes. Although they are mostly observational, cost-effectiveness studies have provided sufficient evidence for the cost-effectiveness of treatment with inhaled steroids, combinations of inhaled corticosteroids and long-acting b₂-agonists (35). Early and long-term treatment with inhaled corticosteroids was found to be cost-effective in patients with mild persistent asthma of recent onset (36). Education and self-management programmes for people with severe asthma were also found to be cost-effective (3739).

The National Cooperative Inner-City Asthma Study (NCICAS) investigated the effectiveness of interventions. A multifaceted asthma intervention programme reduced the number of days on which symptoms occurred and was cost-effective for inner-city children with asthma. In children with more severe disease, the intervention was substantially more effective and reduced costs compared with those seen in control children (40). School-based health centres (41) and social worker-based intervention can boost outcomes and cut costs in inner-city dwellers with asthma (42). Specialist nurse interventions were found to reduce unscheduled asthma care in a deprived multiethnic area of London, England (43). Organizations serving this type of population in both developed and developing countries should consider such a strategy as part of a comprehensive disease-management programme for asthma.

In some countries, nurses are specialized in asthma care and care given by asthma nurses improves outcomes and reduces costs in primary health care (44). Moreover, it was shown that nurse-led outpatient management of childhood asthma can be provided at a lower cost than medical care by paediatricians (45).

Occupational asthma makes a substantial contribution to the total costs of the disease (20, 23). These costs are expected to rise with its increasing prevalence. Intervention strategies for effective prevention and control at the workplace (before asthma has developed) should lessen the burden of long-term illness and its impact on public health costs (19). Early recognition of occupational asthma is an essential step in preventing the onset of severe persistent asthma which could progress even after exposure to the hazardous occupational agent has ceased. Most patients with occupational asthma have rhinitis which often occurs before the onset of bronchial symptoms. In order to prevent the onset and progression of persistent asthma in subjects exposed to known risk factors, it is important to be able to detect the early stages of occupational asthma by identifying nasal symptoms.

Because many patients with asthma are elderly and may suffer from other NCDs, the integration of management programmes for multiple chronic diseases will be the next step in coordinating and improving the care of patients with multiple CRDs as well as in reducing costs (46). Clinical guidelines for CRDs and for other NCDs will need to be integrated into "meta-guidelines" that combine the contents of individual practice guidelines and can be easily applied by general practitioners and other health care workers.

Modelling of predicted costs

Sophisticated models for predicting asthma costs have been proposed. These include probabilistic sensitivity analysis for decision trees with multiple branches using the Dirichlet distribution in a Bayesian framework (47). A Markov model has been used to estimate the cost-effectiveness of alternative asthma treatments (48). However, these models only attempt to assess costs associated with medications and/or asthma exacerbations.

A more global model should be envisaged that would take into account the following.

The natural history of asthma which is a chronic-episodic disease characterized by acute, symptomatic episodes of varying severity (49).

The expected trends in prevalence and morbidity related to asthma within the next 15 years.

The role of indoor allergens (tobacco smoke) and outdoor environmental allergens (pollution), nutrition and occupation in the onset, severity and/or persistence of asthma. Changes in exposure should, however, be considered because the impact of these environmental factors and their comorbid effects are likely to change considerably within the next 15 years as a result of preventive measures (e.g. smoking cessation campaigns) and also because of the exposure to new (or as yet unidentified) causes.

Comorbidities (e.g. asthma and rhinitis, asthma and COPD in smokers) in terms of costs and of the efficacy of drugs in treating asthma.

Asthma affects quality of life, work and school. People with asthma have significant absenteeism from school and work. Patients with asthma and also with rhinitis have an impaired productivity at work or performance at school.

Ageing of the population is a phenomenon that will increasingly affect the management of asthma in the future.

The implementation of guidelines for the management of asthma has been shown to reduce the burden of the disease. In particular, morbidity and mortality from asthma have been reduced in some countries. However, patients' adherence to treatment is still poor. The impact of therapeutic strategies for asthma using published guidelines and the adherence of patients to treatment should also be included in the model. The model should incorporate treatment availability and trends which differ between countries.

It is important to model the socioeconomic costs of asthma according to the different health systems.

Conclusion

The burden of asthma is substantial due to its high prevalence, morbidity and mortality both in developed and developing countries. The trends in prevalence, severity and mortality show that currently the problem is increasing more in developing countries than in developed ones. Barriers to the optimal management of asthma exist throughout the world, but poorer access to, and availability of, drugs in developing countries is a cause of great concern. The workplace environment contributes significantly to the general burden of asthma. Patients with occupational asthma have higher rates of hospitalization and mortality than workers who don't suffer from the condition. The surveillance of asthma as part of a global WHO programme is essential for successful disease management. The economic cost of asthma is considerable both in terms of direct medical costs (such as hospital admissions and the cost of pharmaceuticals) and indirect medical costs (such as time lost from work and premature death). It is essential to attempt to reduce these costs. Poor control of asthma symptoms is a major issue that can lead to adverse clinical and economic outcomes. Models are needed to attempt to reduce asthma costs, while permitting optimal management of the disease.

Competing interests: none declared.

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