Phenotypes, Risk Factors, and Mechanisms of Adult‐Onset Asthma

Abstract

Asthma is a heterogeneous disease with many phenotypes, and age at disease onset is an important factor in separating the phenotypes. Genetic factors, atopy, and early respiratory tract infections are well-recognized factors predisposing to childhood-onset asthma. Adult-onset asthma is more often associated with obesity, smoking, depression, or other life-style or environmental factors, even though genetic factors and respiratory tract infections may also play a role in adult-onset disease. Adult-onset asthma is characterized by absence of atopy and is often severe requiring treatment with high dose of inhaled and/or oral steroids. Variety of risk factors and nonatopic nature of adult-onset disease suggest that variety of mechanisms is involved in the disease pathogenesis and that these mechanisms differ from the pathobiology of childhood-onset asthma with prevailing Th2 airway inflammation. Recognition of the mechanisms and mediators that drive the adult-onset disease helps to develop novel strategies for the treatment. The aim of this review was to summarize the current knowledge on the pathogenesis of adult-onset asthma and to concentrate on the mechanisms and mediators involved in establishing adult-onset asthma in response to specific risk factors. We also discuss the involvement of these mechanisms in the currently recognized phenotypes of adult-onset asthma.

Higher mortality of adults with asthma: A 15‐year follow‐up of a population‐based cohort

“…The increased prevalence of asthma and allergic diseases is a major public health problem affecting 1%‐18% of the population worldwide . Late‐onset asthma is frequently associated with female gender, obesity, depression, gastroesophageal reflux disease, chronic obstructive pulmonary disease (COPD), and higher rate of hospitalizations . Asthma is also shown to be associated with increased risk of coronary heart disease, cerebrovascular disease, and heart failure .…”

Daily physical activity and lung function decline in adult-onset asthma: a 12-year follow-up study

“…Over the past years researchers have identified several phenotypes of asthma revealing the heterogeneity of the disease [5,6]. Age of onset of asthma has been found as a key differentiating factor between the phenotypes.…”

“…Age of onset of asthma has been found as a key differentiating factor between the phenotypes. It has been shown recently that the adult-onset phenotypes differ vastly from childhood-onset asthma [5,6]. Childhood asthma is often an atopic disease characterized by high numbers of bronchial eosinophils and high serum levels of IgE with a good response to glucocorticoid treatment.…”

“…In contrast, patients with disease onset at adulthood have often more severe asthma that rarely remits [7]. Recently, asthma diagnosed at adult-age has been shown to constitute a majority among all new cases of asthma [8], and it seems that several lifestyle factors such as cigarette smoking and obesity are major factors in adult-onset asthma [6,9]. Since the concept of adult-onset phenotypes is rather new, only few studies exist on it and there is no clear consensus on the best therapy for these patients.…”

Determinants of persistent asthma in young adults

“…Common features include fluctuating respiratory symptoms associated with variable airflow limitation and bronchial hyperresponsiveness (BHR) due to inflammation of the airways. The age of asthma onset is an important factor for dividing the phenotypes and a major determinant of the prognosis [3–5], but the prognosis for adult-onset asthma is only sparsely documented [6]. In a prospective study of individuals with adult-onset asthma higher age, higher body mass index (BMI) and low lung function were associated with greater asthma severity, while non-sensitisation and a normal lung function were predictors for remission [7].…”