An estimated 20% of individuals with asthma smoke cigarettes, and these individuals are characterized by unique clinical features, outcomes, and treatment needs.1 Compared with nonsmokers with asthma, smokers with asthma have elevated morbidity and mortality, worse asthma control, more frequent exacerbations and severe symptoms, and a greater incidence of life-threatening attacks.1

Individuals who smoke are also more likely to experience a more rapid decline in lung function and permanent chronic airflow obstruction, with a 3-fold risk of airflow obstruction in patients with nonatopic asthma, in particular.1 In addition, a recently published longitudinal study found that the incidence of new adult-onset asthma was 40% to 20% higher in active and passive smokers, respectively, compared with nonsmokers with asthma.2

Despite such findings, however, asthmatic smokers, and even former smokers, are typically excluded from trials investigating asthma therapies. As a result, there is a lack of clarity regarding optimal treatment options for these patients. According to a narrative review published in 2016 in Asthma Research and Practice, clinicians should emphatically encourage asthmatic smokers to stop smoking and provide information regarding the risks of smoking and benefits of quitting.1

Smoking Cessation in Patients With Asthma

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Studies have shown that smoking cessation in patients with asthma is associated with reduced asthma symptoms, improved lung function and quality of life, reduced use of rescue medications, improved airway hyperresponsiveness, and decreased hyperactivity. “A plausible explanation for the improvement in various outcomes is that there is a gradual and progressive reduction of proinflammatory effects in the airways related to the decreased inhalation of cigarette smoke,” the review investigators wrote.1

Clinicians should also inform patients that numerous cessation attempts may be necessary before they quit definitively, and clinicians should be familiar with basic behavioral techniques to help patients choose strategies to deal with smoking triggers and withdrawal symptoms. The first-line smoking cessation agents buproprion and varenicline have been shown to increase cessation success rates.1

One study examined the use of varenicline in smokers with asthma and found increased rates of cessation and improved airway hyperresponsivness compared with placebo.3 According to the review, “In general, the best strategy for preventing relapse and producing high long-term abstinence rates appears to be the combined use of the most effective cessation.”1

Limited data suggest that electronic nicotine delivery devices may be an effective harm reduction strategy in patients who have exceptional difficulty quitting smoking, although further research is needed in this area. In a retrospective study of 18 smokers with asthma, patients who switched from conventional to electronic cigarettes demonstrated improved asthma control and pulmonary function and decreased airway hyperreactivity.4

Treating Asthmatic Smokers

While corticosteroids should generally be included in the treatment strategy for most patients with asthma, study results indicate that up to one-third of asthmatic smokers do not respond to these drugs.5 “A possible mechanism for the corticosteroids insensitivity or resistance may be the increased airway mucosal permeability in smokers, which could lead to increased clearance of inhaled corticosteroids (ICS) from the airways,” the review investigators explained. “Smokers also have decreased histone deacetylase (HDAC) activity, which is necessary for corticosteroids to suppress cytokine production.”1