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Abstract
Summary Asthma is an inflammatory disorder of the conducting airways which undergo distinct structural and functional changes, leading to nonspecifir BHR (bronchial hyper-responsiveness) and airflow obstruction that fluctuates over time. Based on the application of standardized methods to measure the prevalence of asthma and wheezing illness in children and adults, it appears that the global prevalence of asthma ranges from 1% to 18% of the population in different countries. In Egypt, a prevalence of 8.2% among school children aged 5-15 years old was reported Most, but not all, asthma is associated with atopy (the inherited predisposition to generate IgE against common environmental allergens).This has led asthma to be regarded largely as an allergic disorder along with other atopic diseases. However, asthma prevention has not been achieved with allergen-reduction strategies, once established there is no cure and there are currently no medications that can alter the naturalhistory of the disease. Asthma can no longer be considered simply in terms as a single cellular and mediator response to inhaled allergens, but a complex interaction between the inhaled environment and the formed elements of the airways. Of importance is the concept that the state of the airway epithelium and underlying mesenchyme (EMTU) may be crucial in translating the atopic phenotype into the lower airways, and this may vary over time and between patients giving rise to different subphenotypes with differing responses to treatment and natural histories. In primary care, in which most asthma patients are managed, the diagnosis of asthma is mainly symptom based. In this setting, the assessment of AHR and airway inflammation is not easy; therefore, these domains of asthma are not assessed. Lung function and SPT are not measured as recommended in guidelines. Diagnosing asthma in infants and children remains a challenge despite the new tools available. Clinical approach, predicting tests (eg, API), and a trial of bronchodilators or glucocorticosteroids are still helpful. In the future, research following epidemiologic studies, which tend to present a more accurate phenotypic approach, and the development of newer noninvasive diagnostic tools might be the key to opening a new avenue to early diagnosis and treatment. Management is primarily directed towards suppressing airway inflammation with inhaled corticosteroids and relieving bronchoconstriction with bronchodilators. Apart from corticosteroids, the only oral medications in widespread use are cysteinyl LT (leukotriene)receptor 1 antagonists that inhibit the bronchoconstrictor and inflammatory actions .All of these therapies exert their effect downstream of the origins of asthma. There is an urgent need to identify the underlying basis of asthma, understand the complex genetic and environmental influences, and develop appropriate treatment strategies. Although asthma may start at any time in life, the majority begins in early childhood, and, although it may spontaneously remit, longitudinal studies reveal that later relapses frequently occur. Severe irreversible airflow obstruction may develop despite apparently appropriate use of controller therapy, as advocated by international and national disease management guidelines. That is not to say that widespread adherence to anti-inflammatory controller therapy does not influence long-term outcomes of asthma; indeed, when treatment adherence is high, as in Finland, asthma mortality and morbidity can be dramatically reduced. The problem is that, in most countries of the world, treatment adherence is low, especially when inhaled drugs are involved on account of perceived fear of systemic side effects, addiction and concerns over acquisition of drug resistance.In low- and middle-income countries, inadequate diagnosis, the costs of drugs and poor education all contribute to poor disease management and overdependence on emergency interventions with the consequence of high mortality and morbidity. Connecting life-course studies with mechanistic research in wellphenotyped patients should provide much needed new insight into disease mechanisms and, hopefully, will lead to the identification of new therapeutic targets for disease prevention and treatment.