global strategy for asthma management and prevention

GINA_WR_2006.qxp:GINA_WR_2006.qxp 7/20/07 4:12 PM Page 9pollutants 115 , and even certain weather conditions, e.g.,thunderstorms 116 . More prolonged worsening is usuallydue to viral infections of the upper respiratory tract(particularly rhinovirus and respiratory syncytial virus) 117or allergen exposure which increase inflammation in thelower airways (acute on chronic inflammation) that maypersist for several days or weeks.Nocturnal asthma. The mechanisms accounting for theworsening of asthma at night are not completelyunderstood but may be driven by circadian rhythms ofcirculating hormones such as epinephrine, cortisol, andmelatonin and neural mechanisms such as cholinergictone. An increase in airway inflammation at night has beenreported. This might reflect a reduction in endogenousanti-inflammatory mechanisms 118 .Irreversible airflow limitation. Some patients with severeasthma develop progressive airflow limitation that is notfully reversible with currently available therapy. This mayreflect the changes in airway structure in chronic asthma 119 .Difficult-to-treat asthma. The reasons why somepatients develop asthma that is difficult to manage andrelatively insensitive to the effects of glucocorticosteroidsare not well understood. Common associations are poorcompliance with treatment and physchological andpsychiatric disorders. However, genetic factors maycontribute in some. Many of these patients have difficultto-treatasthma from the onset of the disease, rather thanprogressing from milder asthma. In these patients airwayclosure leads to air trapping and hyperinflation. Althoughthe pathology appears broadly similar to other forms ofasthma, there is an increase in neutrophils, more smallairway involvement, and more structural changes 100 .Smoking and asthma. Tobacco smoking makes asthmamore difficult to control, results in more frequentexacerbations and hospital admissions, and produces amore rapid decline in lung function and an increased riskof death 120 . Asthma patients who smoke may have aneutrophil-predominant inflammation in their airways andare poorly responsive to glucocorticosteroids.REFERENCES1. Reddel H, Ware S, Marks G, et al. Differences between asthmaexacerbations and poor asthma control. Lancet 1999; 353: 364-9.2. Masoli M, Fabian D, Holt S, Beasley R. The global burden ofasthma: executive summary of the GINA DisseminationCommittee report. Allergy 2004;59(5):469-78.3. Beasley R. The Global Burden of Asthma Report, Global Initiativefor Asthma (GINA). Available from http://www.ginasthma.org 2004.4. Yan DC, Ou LS, Tsai TL, Wu WF, Huang JL. Prevalence andseverity of symptoms of asthma, rhinitis, and eczema in 13- to14-year-old children in Taipei, Taiwan. Ann Allergy AsthmaImmunol 2005;95(6):579-85.5. 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Stabilization of asthma prevalenceamong adolescents and increase among schoolchildren(ISAAC phases I and III) in Spain. Allergy 2004;59(12):1301-7.9. Mahapatra P. Social, economic and cultural aspects of asthma:an exploratory study in Andra Pradesh, India. Hyderbad, India:Institute of Health Systems; 1993.10. Lai CK, De Guia TS, Kim YY, Kuo SH, Mukhopadhyay A,Soriano JB, et al. Asthma control in the Asia-Pacific region:the Asthma Insights and Reality in Asia-Pacific Study. J AllergyClin Immunol 2003;111(2):263-8.11. Lenney W. The burden of pediatric asthma. Pediatr PulmonolSuppl 1997;15:13-6.12. Neffen H, Fritscher C, Schacht FC, Levy G, Chiarella P,Soriano JB, et al. Asthma control in Latin America: the AsthmaInsights and Reality in Latin America (AIRLA) survey. RevPanam Salud Publica 2005;17(3):191-7.13. Weiss KB, Gergen PJ, Hodgson TA. An economic evaluation ofasthma in the United States. N Engl J Med 1992;326(13):862-6.14. Weinstein MC, Stason WB. Foundations of cost-effectivenessanalysis for health and medical practices. N Engl J Med1977;296(13):716-21.15. Weiss KB, Sullivan SD. The economic costs of asthma: a reviewand conceptual model. Pharmacoeconomics 1993;4(1):14-30.16. Action asthma: the occurrence and cost of asthma. West Sussex,United Kingdom: Cambridge Medical Publications; 1990.17. Marion RJ, Creer TL, Reynolds RV. Direct and indirect costsassociated with the management of childhood asthma. AnnAllergy 1985;54(1):31-4.DEFINITION AND OVERVIEW 9