Difficult-to-control asthma

Abstract

Purpose of review The aim of the present review is to discuss the epidemiology of inadequate asthma control with an examination of contributing environmental factors. Recent findings Despite advances in asthma therapies, a proportion of patients with asthma continue to have difficulty gaining adequate asthma control. Asthma severity and control in childhood is of particular importance as it translates to asthma morbidity in adulthood. Children with comorbid severe allergic rhinitis were more likely to have uncontrolled asthma. Recent data suggest that mouse allergen, more so than cockroach allergen, may be the most relevant urban allergen exposure. Tobacco smoke exposure, even passive exposure, leads to increased asthma symptoms and decreased response to inhaled corticosteroids. Efforts to ban smoking in public places have resulted in promising asthma results for entire populations. Energy saving efforts to tighten a home’s air leaks can lead to increased indoor pollutant levels and, therefore, must be accompanied by efforts to reduce, filter, or exchange indoor pollutants. Obesity is independently associated with decreased asthma control. Furthermore, the detrimental effects of pollutant exposure are enhanced in an overweight individual with asthma. Summary Lack of asthma control can be due to a complex web of factors including adherence, intrinsic factors, and environmental exposures. Further research on intervention strategies is needed to achieve improved rates of asthma control.

The association between environmental tobacco smoke exposure and childhood respiratory disease: a review

“…A 20% increased length of hospital stay was also found in ETS-exposed asthmatic children [57]. ETS exposure also impacts on asthma control with decreased response to inhaled corticosteroids and impaired histone deacetylase-2 function, possibly contributing to steroid resistance in asthmatic children [58]. In utero tobacco smoke exposure increased age-related airway hyperresponsiveness and reduced the efficacy of inhaled corticosteroids in asthmatic children [59].…”

Is allergic sensitization relevant in severe asthma? Which allergens may be culprits?

“…Cockroaches produce several allergens that induce sensitization, and exposure to high levels of cockroach allergens at home is a major risk factor for symptoms in sensitized individuals [68]. Recent data suggest that cockroach allergen may be a most relevant urban allergen exposure and may be related to asthma severity [69]. Indoor allergen exposure in inner-city areas has been of particular interest given that patients living in urban areas have increased asthma severity, decreased asthma control, and greater health care use [70].…”

New Insights into Cockroach Allergens

“…Ahluwalia et al observed that sensitization/exposure to both mouse and cockroach was associated with worse asthma in an inner-city community in Baltimore exposed to high levels of both allergens. However, mouse allergen appeared to be more strongly and consistently associated with poor asthma outcomes than cockroach allergen [16,17]. …”