Asthma Epidemiology

Summary

Although asthma remains poorly defined , major advances are being made in understanding its epidemiology . The condition varies greatly in prevalence but is now common in many countries , both developed and developing . Evidence from objective tests suggests that this is not a matter of reporting bias . The prevalence of the disease has been increasing over the last half a century . Asthma is the most prevalent chronic disease of children and is the number one reason for school absence , emergency room and hospital admissions . At least part of this increase appears to be related to an increase in sensitivity to common allergens . There is a strong genetic contribution to asthma , but it seems increasingly likely that this is due to a large number of gene polymorphisms . It is also clear that the variation in prevalence  of the disease is largely accounted for by changes in the environment .

 Environmental risk factors that are currently under discussion include changes in life styles ( urban or rural ) . diet , lack of infections , particularly gut infections in early life , exposure to allergens , cigarette smoking and air pollution ( indoor and outdoor ) . Such factors may influence either the likelihood of becoming sensitized to allergens or the risk of developing  asthma if sensitized . To maximize the value of epidemiological research . the International study of Asthma and Allergies in Childhood (ISAAC) was designed in 1992 to study the prevalence of asthma . allergic rhinitis and eczema in different countries of the world including Iran. Also , the National Asthma Registry has been approved by the Committee of Iranian Asthma and Allergy . to be investigated with the collaboration  of the Immunology.  Asthma and Allergy Research Institute (IAARI) .

longitudinal studies show that a topic asthma in childhood generally persists into adult life. There is mixed evidence as to whether asthmatic patients on average have a more rapid decline in lung function over the time than would be expected , but some studies suggest that this is so. Death from asthma is rare in early childhood but becomes more common with increasing age . The mortality rates of asthma among people of 5 to 34 years old have risen markedly each year from 1979 to 1995 . In the younger age groups , the mortality rates have changed relatively a little over the past century , though there have been periods of mortality . These  increased have been associated with changes in treatment practice . Other environmental factors associated with asthma deaths are suggested by sea sol variations.

Asthma is very costing and drains the nation’s health-care budget. Both the direct and indirect costs of asthma is increasing worldwide . Although appropriate management of people with asthma should decrease the overall cost of the disease in the society , the most important benefit would be the improved health and well being of people with asthma and their families.