Effect of smoking abstinence and reduction in asthmatic smokers switching to electronic cigarettes: evidence for harm reversal.

Electronic cigarettes (e-cigs) are marketed as safer alternatives to tobacco cigarettes and have shown to reduce their consumption. Here we report for the first time the effects of e-cigs on subjective and objective asthma parameters as well as tolerability in asthmatic smokers who quit or reduced their tobacco consumption by switching to these products. We retrospectively reviewed changes in spirometry data, airway hyper-responsiveness (AHR), asthma exacerbations and subjective asthma control in smoking asthmatics who switched to regular e-cig use. Measurements were taken prior to switching (baseline) and at two consecutive visits (Follow-up/1 at 6 (±1) and Follow-up/2 at 12 (±2) months). Eighteen smoking asthmatics (10 single users, eight dual users) were identified. Overall there were significant improvements in spirometry data, asthma control and AHR. These positive outcomes were noted in single and dual users. Reduction in exacerbation rates was reported, but was not significant. No severe adverse events were noted. This small retrospective study indicates that regular use of e-cigs to substitute smoking is associated with objective and subjective improvements in asthma outcomes. Considering that e-cig use is reportedly less harmful than conventional smoking and can lead to reduced cigarette consumption with subsequent improvements in asthma outcomes, this study shows that e-cigs can be a valid option for asthmatic patients who cannot quit smoking by other methods.