Page 12 - ADULT-ONSET ASTHMA PREDICTORS OF CLINICAL COURSE AND SEVERITY

ADULT-ONSET ASTHMA – PREDICTORS OF CLINICAL COURSE AND SEVERITY
EPIDEMIOLOGY AND RISK FACTORS OF ADULT-ONSET ASTHMA
Asthma is a common respiratory disease that affects 334 million people of all ages worldwide.1 Characteris cs of asthma are typical symptoms (wheezing, chest ghtness, shortness of breath), reversible airway obstruc on, bronchial hyperreac vity and chronic airway in amma on.2 Asthma has been regarded for a long me as a disease that develops in childhood. Gene c predisposi on, atopy and respiratory infec ons early in life have been established as the major risk factors for developing the disease.3, 4 The prognosis is generally considered favourable, up to 65% of children has “overgrown” their asthma when they are middle aged.5 However, since several decades a di erent asthma type that emerges in adulthood has been recognized, so called adult-onset asthma.6-9 This type of asthma di ers from childhood onset asthma with respect to epidemiology, risk factors, phenotypes, pathophysiology and probably also prognosis.10
Childhood asthma has an incidence of 3.7-5.2 per 1000 person-years and the incidence decreases with increasing age.3, 11 Boys are more prone to develop asthma in childhood than girls (4.5 vs 2.9/1000).3 On the contrary, the incidence of adult-onset asthma in women was es mated 4.6 per 1000 person-years and 3.6 per 1000 person-years in men in a pooled analysis of several popula on studies. A trend towards a higher incidence was seen with increasing age (see Figure 1).11, 12 Consequently the prevalence of asthma rises with age and ranges from 6-10% in older adults.13 In contrast to the limited number of risk factors for childhood asthma, a wide range of in uencing factors for the development of adult-onset asthma have been found. These include gene c factors,14, 15 exposure to occupa onal agents like wheat our and cleaning products,16, 17 air pollu on,18 cigare e smoke exposure,15, 19, 20 respiratory infec ons,21 NSAID hypersensi vity,22, 23 female sex hormones,24 stress25 and obesity.26, 27
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