Table:
Baseline characteristics
| Cigarette substitute group (n=130) | ENDS with 0 mg/mL nicotine group (n=130) | ENDS with 8 mg/mL nicotine group (n=130) | ENDS with 36 mg/mL nicotine group (n=130) | Overall (n=520) | |
|---|---|---|---|---|---|
| Age, years | 46·1 (12·4) | 45·7 (11·4) | 45·6 (11·7) | 47·4 (11·1) | 46·2 (11·6) |
| Sex | |||||
| Female | 79 (61%) | 80 (62%) | 80 (62%) | 67 (52%) | 306 (59%) |
| Male | 51 (39%) | 50 (38%) | 50 (38%) | 63 (48%) | 214 (41%) |
| Ethnicity | |||||
| White non-Hispanic | 83 (64%) | 92 (71%) | 87 (67%) | 88 (68%) | 350 (67%) |
| Black non-Hispanic | 39 (30%) | 33 (25%) | 37 (28%) | 36 (28%) | 145 (28%) |
| Other | 8 (6%) | 5 (4%) | 6 (5%) | 6 (5%) | 25 (5%) |
| Some college education or higher | 76 (58%) | 72 (55%) | 83 (64%) | 79 (61%) | 310 (60%) |
| Income >US$39 999* | 51 (40%) | 47 (37%) | 51 (41%) | 60 (46%) | 209 (41%) |
| Cigarettes smoked per day, mean over 7 days† | 18·37 (7·13) | 18·79 (8·35) | 19·45 (8·73) | 17·76 (6·52) | 18·59 (7·74) |
| Exhaled CO, ppm | 23·65 (12·54) | 23·35 (12·23) | 21·84 (9·80) | 21·94 (10·48) | 22·69 (11·32) |
| Penn State Cigarette Dependence Index score | 13·4 (3·0) | 13·7 (2·7) | 13·2 (3·0) | 13·2 (3·2) | 13·4 (3·0) |
| Menthol cigarette smoking | 87 (67%) | 88 (68%) | 81 (62%) | 77 (59%) | 333 (64%) |
| Use of other tobacco products in past 30 days | 4 (3%) | 9 (7%) | 10 (8%) | 8 (6%) | 31 (6%) |
| Urinary total NNAL, pg/mg creatinine | |||||
| Median (IQR) | 441·42 (683·19) | 499·76 (612·20) | 419·97 (835·64) | 544·38 (825·33) | 473·18 (710·61) |
| Geometric mean (95% CI) | 404·22 (33047–49444) | 440·69 (366·42–530·01) | 425·04 (347·34–520·11) | 432·73 (339·33–551·83) | 425·45 (383·64–471·81) |
| Urinary cotinine, ng/mg creatinine | |||||
| Median (IQR) | 1641·21 (2018·30) | 1593·17 (1564·13) | 1733·97 (2057·46) | 1871·47 (2137·68) | 1662·45 (1908·58) |
| Geometric mean (95% CI) | 1441·56 (1227·93–1692·35) | 1444·53 (1241·45–1680·83) | 1729·53 (1493·97–2002·23) | 1658·74 (1411·23–1949·67) | 1563·39 (1447·38–1688·70) |
Data are mean (SD) or n (%) unless otherwise stated. Demographic characteristics and use of other tobacco products were assessed by self-report at the in-person screening visit (1 week before randomisation). Cigarettes smoked per day, exhaled CO, Penn State Cigarette Dependence Index score, menthol cigarette smoking status, urinary total NNAL, and urinary cotinine were assessed at the baseline visit (at randomisation). There were no significant differences in baseline characteristics between groups (p>0·05 for each characteristic). ENDS=electronic nicotine delivery system. ppm=parts per million. NNAL=4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol.
Two participants in the cigarette substitute group, three in the 0 mg/mL group, and five in the 8 mg/mL group had missing income data.
Calculated using self-reported timeline follow-back for the 7 days before the randomisation visit (collected in-person at randomisation).