Biologic Mechanisms of Environmental Tobacco Smoke in Children with Poorly Controlled Asthma: Results from a Multicenter Clinical Trial

Abstract

Background Environmental tobacco smoke (ETS) negatively affects children with asthma. The prevalence of ETS exposure among children with poor asthma control may be changing. Importantly, the mechanisms by which ETS worsens asthma control are poorly understood. Objective We describe how ETS affects gastroesophageal reflux (GER), respiratory infections, and leukotriene production among children with poor asthma control. Methods We analyzed data from 306 children between 6 and 17 years of age with poorly controlled asthma enrolled in a 6-month clinical trial. We evaluated prevalence and determinants of ETS exposure by interview, questionnaire, and urinary cotinine and the association of ETS exposure on leukotriene production, respiratory infections, GER, lung function, and asthma control. We used multivariable linear, logistic, and Poisson regressions to assess outcomes. Results ETS prevalence estimates ranged from 6% to 30%. Children with domestic indoor exposure had worse asthma control (c-Asthma Control Test, 17.8 vs 21.5; P = .04), worse FEV1 % predicted (84.1 vs 90.7; P = .02), and a trend for increased mean urinary leukotriene E4. ETS from any setting was associated with increased symptomatic respiratory infections (adjusted incidence rate ratio: 1.30; P =.02). However, children exposed to ETS did not have symptoms or pH probe results, suggestive of heightened GER. Conclusions Domestic smoking exposure was associated with both higher rates of symptomatic respiratory infection and poorer asthma control despite generally intensive controller therapy. ETS exposure is common among asthmatic children with poor control and may worsen asthma control by promoting respiratory infections. Further investigation is required to elucidate ETS mechanisms in poor asthma control.

Factors associated with high short-acting β2-agonist use in urban children with asthma

“…10, 21-23 Indoor SHS exposure, particularly maternal smoking, was associated with a 52% increased risk of wheeze and 20% increased risk of asthma at age 5-18 years, 24 and any home SHS exposure was associated with increased asthma symptoms. 25 Identifying factors associated with frequent SABA medication use, indicative of poor asthma control, including allergen sensitization and indoor exposures to allergens and SHS may be helpful in targeting individualized environmental control as well as community level asthma interventions for inner-city families. Therefore, the objective of this study was to examine factors, including allergic sensitization and second hand smoke (SHS) exposure, associated with high SABA use among low-income inner-city children with frequent ED visits for asthma.…”

Biomarkers of asthma and allergic airway diseases

“…58 Urinary LTE4 concentrations also have been associated with acute exacerbations of asthma 59 and the degree of airflow limitation, 57 but some confounding of the biomarker might exist. Recent studies have suggested that LTE4 concentrations are increased in response to environmental tobacco smoke exposure 60 ; however, increased LTE4 concentrations are still predictive of future exacerbations in children with asthma exposed to secondhand smoke. 61 Other prospective clinical trials in which urinary LTE4 was assessed as a biomarker remain promising.…”

Passive smoking interference with wheezing and asthma: short review of current knowledge

“…In addition, other genes with potential interactions with tobacco smoking and risk for asthma exacerbations have been identified in candidate gene linkage approaches [19][20][21][22].…”