Abstract
OBJECTIVE: Reducing nicotine levels in cigarettes decreases smoking, which is enhanced by access to preferred-flavor e-cigarettes. Smoking increases risk of cardiopulmonary disease, but effects of very-low-nicotine-content cigarettes (VLNCs) in combination with e-cigarettes are unknown. Health effects of nicotine-reduction approaches must be examined. METHODS: Data were from three randomized controlled trials conducted at the University of Vermont, Brown University, and Johns Hopkins University (October 2020-November 2023). Effects, within vulnerable populations, of 16 weeks of normal nicotine content cigarettes (NNC), VLNCs only, VLNCs plus e-cigarettes in only tobacco flavor (VLNC+TF), or VLNCs in combination with the option to select from eight commonly preferred flavors (VLNC+PF) were tested. Cardiopulmonary measures included vital signs and subjective respiratory symptoms. Effect of experimental condition on outcomes were examined using multivariable linear mixed models controlling for baseline values, age, sex, study week, and vulnerable population (lower-educated women [n = 80], those with opioid use disorder [n = 74], or affective disorders [n = 172]). RESULTS: Most (243/326, 74.5 %) participants were high-risk for cardiopulmonary disease (i.e., hypertension). There were no significant effects of experimental condition on objective cardiac or pulmonary measures. Within respiratory symptoms there were significant effects of condition on subjective ratings of cough severity especially among patients with preexisting disease (F(3,48) = 4.02, p = 0.01, partial η(2) = 0.08) with higher severity ratings in the NNC and VLNC+PF compared to VLNC alone or VLNC+TF conditions (Ps < 0.05). CONCLUSIONS: Combining VLNCs with e-cigarettes in preferred flavors appears to have no adverse effects on objective cardiopulmonary measures but may increase subjective ratings of cough severity in higher-risk pulmonary subpopulations.