IMPORTANCE Electronic cigarettes (e-cigarettes) for smoking cessation remain controversial. OBJECTIVE To evaluate e-cigarettes with individual counseling for smoking cessation. DESIGN, SETTING, AND PARTICIPANTS A randomized clinical trial enrolled adults motivated to quit smoking from November 2016 to September 2019 at 17 Canadian sites (801 individuals screened; 274 ineligible and 151 declined). Manufacturing delays resulted in early termination (376/486 participants, 77% of target). Outcomes through 24 weeks (March 2020) are reported. INTERVENTIONS Randomization to nicotine e-cigarettes (n = 128), nonnicotine e-cigarettes (n = 127), or no e-cigarettes (n = 121) for 12 weeks. All groups received individual counseling. MAIN OUTCOMES AND MEASURESThe primary end point was point prevalence abstinence (7-day recall, biochemically validated using expired carbon monoxide) at 12 weeks, changed from 52 weeks following early termination. Participants missing data were assumed to be smoking. The 7 secondary end points, examined at multiple follow-ups, were point prevalence abstinence at other follow-ups, continuous abstinence, daily cigarette consumption change, serious adverse events, adverse events, dropouts due to adverse effects, and treatment adherence. RESULTS Among 376 randomized participants (mean age, 52 years; 178 women [47%]), 299 (80%) and 278 (74%) self-reported smoking status at 12 and 24 weeks, respectively. Point prevalence abstinence was significantly greater for nicotine e-cigarettes plus counseling vs counseling alone at 12 weeks (21.9% vs 9.1%; risk difference [RD], 12.8 [95% CI, 4.0 to 21.6]) but not 24 weeks (17.2% vs 9.9%; RD, 7.3 [95% CI,). Point prevalence abstinence for nonnicotine e-cigarettes plus counseling was not significantly different from counseling alone at 12 weeks (17.3% vs 9.1%; RD, 8.2 [95% CI, -0.1 to 16.6]), but was significantly greater at 24 weeks (20.5% vs 9.9%; RD, 10.6 [95% CI, 1.8 to 19.4]). Adverse events were common (nicotine e-cigarette with counseling: 120 [94%]; nonnicotine e-cigarette with counseling: 118 [93%]; counseling only: 88 [73%]), with the most common being cough (64%) and dry mouth (53%).CONCLUSIONS AND RELEVANCE Among adults motivated to quit smoking, nicotine e-cigarettes plus counseling vs counseling alone significantly increased point prevalence abstinence at 12 weeks. However, the difference was no longer significant at 24 weeks, and trial interpretation is limited by early termination and inconsistent findings for nicotine and nonnicotine e-cigarettes, suggesting further research is needed.

The body composition of 40 healthy elderly and 20 healthy young subjects was determined and compared. It was found that the age-related changes were more marked in females than in males. Total body water was decreased as a consequence of diminished lean body mass. Extracellular fluid volume remained unchanged, while plasma volume increased. Thus, the liquid components of lean body mass were redistributed between the intracellular and extracellular spaces. The elimination kinetics of isotopes were not significantly different between young and aged subjects, except the elimination of radiosulfate.

The predictive values of the equations of Moore et al. and Hume and Weyers and the measured values of body composition were compared in healthy, carefully selected aged and young subjects of both sexes. In the case of young subjects, these prediction equations seem to be adequate, even if this could not be affirmed with certainty by our results. The equations of Moore et al. were found not to be adequate for elderly males, while they were only suitable for the determination of intracellular components in elderly females.

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