Introduction: E-cigarettes have potential to support tobacco cessation or reduction, but how nicotine content affects smokers' subjective perceptions and use of e-cigarettes, rather than tobacco, is unclear.
Method: Thirty-five adult daily smokers who had not previously tried e-cigarettes were recruited from two cities in New Zealand in 2016-2017. Smokers were given four e-cigarette cartridges (0, 6, 12, and 18 mg nicotine) in a randomized, blinded order over four 2-week periods. Daily cigarette smoking and e-cigarette use was monitored using ecological momentary analysis and participants completed the modified Cigarette Evaluation Questionnaire after each 2-week period.
Results: Mean cigarettes per day decreased by 37% (9.69 to 6.09) when e-cigarettes were available relative to baseline (p = .008). Nicotine-containing cartridges (>0 mg) were associated with greater use (p = .023) and craving reduction (p = .026) than 0 mg. Alleviation of withdrawal symptoms (p = .048) and taste and enjoyment factors (p = .039) predicted e-cigarette use.
Conclusion: Availability of e-cigarettes reduced cigarette smoking behavior regardless of nicotine content, and e-cigarette use was greater with nicotine-containing cartridges. First-time users' e-cigarette use can be predicted using subjective ratings and more research is required to clarify the effect of nicotine content on subjective perceptions and use.
Implications: For low-moderate dependence smokers, availability of e-cigarettes may reduce cigarette smoking behavior regardless of nicotine content, but the availability of nicotine-containing cartridges may promote greater e-cigarette use. First response to trialing e-cigarettes is an important factor in determining subsequent experimental and possibly longer-term use.