Changes in breathomics from a 1-year randomized smoking cessation trial of electronic cigarettes.

Background: Electronic cigarette (EC) use is an emerging behaviour that has been shown to help smokers to reduce cigarette consumption. The aim of this study was to illustrate long-term changes in exhaled breath measurements and respiratory symptoms in smokers invited to quit or reduce their cigarette consumption by switching to ECs. Materials and methods: Prospective evaluation of cigarette consumption, fractional nitric oxide concentration in exhaled breath (FeNO), exhaled carbon monoxide (eCO) and symptom scores was performed in a 1-year randomized, controlled trial of ‘healthy’ smokers receiving 2·4% nicotine, 1·8% nicotine or no nicotine ECs. FeNO and eCO data are presented on the basis of participants’ pooled continuous smoking phenotype classification (failures, reducers and quitters). Results: A significant effect of quitting classification was found on FeNo and eCO at all time points (P < 0·0001). Among quitters, FeNO (medians and interquartile range) rose from 5·5 (4·5–6·9) ppb to 17·7 (13·3–18·9) ppb by week 52. Baseline eCO (medians and interquartile range) decreased from 17 (12–20) ppm to 3 (1–4) ppm by week 52. No significant changes in FeNO and eCO levels were observed in failures and reducers. Improvements in FeNO and eCO levels were correlated with attenuations in symptom scores. Conclusions: Smokers invited to switch to electronic cigarettes who completely abstained from smoking showed steady progressive improvements in their exhaled breath measurements and symptom scores. FeNo and eCO normalization is highly supportive of improved respiratory health outcomes and adds to the notion that quitting from tobacco smoking can reverse harm in the lung.