Changes in breathomics from a 1-year randomised 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 respiratorysymptoms in smokers invited to quit or reduce their cigarette consumption byswitching to ECs.MATERIALS AND METHODS: Prospective evaluation of cigarette consumption,fractional nitric oxide concentration in exhaled breath (FeNO), exhaled carbonmonoxide (eCO) and symptom scores was performed in a 1-year randomized,controlled trial of 'healthy' smokers receiving 2·4% nicotine, 1·8% nicotine orno nicotine ECs. FeNO and eCO data are presented on the basis of participants'pooled continuous smoking phenotype classification (failures, reducers andquitters).RESULTS: A significant effect of quitting classification was found on FeNo andeCO at all time points (P < 0·0001). Among quitters, FeNO (medians andinterquartile 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 wereobserved in failures and reducers. Improvements in FeNO and eCO levels werecorrelated with attenuations in symptom scores.CONCLUSIONS: Smokers invited to switch to electronic cigarettes who completelyabstained from smoking showed steady progressive improvements in their exhaledbreath measurements and symptom scores. FeNo and eCO normalization is highlysupportive of improved respiratory health outcomes and adds to the notion thatquitting from tobacco smoking can reverse harm in the lung.