Table 1.
Study/participant characteristics and descriptive statistics (mean (SD) or %) for plasma nicotine and puff topography
| Study N | E-cigarette-experienced users | E-cigarette-naïve cigarette smokers | E-cigarette-experienced users combined | E-cigarette-naïve cigarette smokers combined | Total sample | |||
|---|---|---|---|---|---|---|---|---|
| Spindle et al24 | Hiler et al6 | Hiler et al6 | Unpublished study #1 | Unpublished study #2 | ||||
| 30 | 33 | 31 | 13 | 23 | 63 | 67 | 130 | |
| Study characteristics | ||||||||
| Liquid nicotine concentration | 18 mg/mL | 36 mg/mL | 36 mg/mL | 36 mg/mL | 25 mg/mL | 18 and 36 mg/mL | 25 and 36 mg/mL | 18, 25, 36 mg/mL |
| Liquid PG/VG ratio | 55/45 | 70/30 | 70/30 | 70/30 | 70/30 | 55/45 and 70/30 | 70/30 | 55/45 and 70/30 |
| Liquid flavours | T | T and M | T and M | T and M | T and M | T and M | T and M | T and M |
| Presession nicotine/tobacco abstinence | Yes | Yes | Yes | No | No | Yes | Yes and no | Yes and no |
| Demographic/tobacco use characteristics | ||||||||
| % male | 96.7 | 81.8 | 58.1 | 76.9 | 70.0 | 88.0 | 66.0 | 77.0 |
| % white | 70.0 | 78.8 | 51.6 | 38.5 | 65.2 | 74.6 | 53.7 | 64.0 |
| % African-American or black | 6.7 | 12.1 | 35.5 | 61.5 | 34.8 | 9.5 | 40.3 | 25.4 |
| % all other races | 23.3 | 9.1 | 12.9 | 0.0 | 0.0 | 15.9 | 6.0 | 10.8 |
| Age (years) | 26.89 (7.12) | 30.31 (8.36) | 30.69 (10.05) | 41.5 (11.0) | 39.61 (14.47) | 28.7 (7.9) | 36.0 (12.7) | 32.4 (11.2) |
| FTND score | – | – | 4.71 (1.90) | 5.54 (1.71) | 5.22 (1.70) | – | 5.0 (1.8) | |
| Carbon monoxide (ppm) | 2.93 (2.21) | 3.00 (2.03) | 20.06 (5.68) | 18.23 (3.40) | 19.13 (7.05) | 3.0 (2.1) | 10.5 (10.0) | |
| Cigarettes/day | 0.03 (0.18) | 0.24 (0.75) | 16.71 (9.44) | 17.85 (6.60) | 16.65 (6.64) | 0.1 (0.6) | 16.9 (8.0) | |
| Years smoking | – | – | 9.30 (9.63) | 16.54 (12.38) | 19.58 (15.13) | – | 13.9 (12.8) | |
| Years e-cigarette use | 1.38 (1.02) | 1.44 (0.82) | – | – | – | 1.4 (0.9) | ||
| Millilitres liquid/day | 6.28 (5.65) | 3.55 (3.78) | – | – | 4.9 (4.9) | |||
| Mg/mL of own brand liquid | 8.50 (4.25) | 17.5 (5.40) | ||||||
| % menthol preference | 61 | 62 | 56 | 60 | ||||
| Nicotine/topography outcomes | ||||||||
| Prenicotine concentration (ng/mL) | 3.10 (3.91) | 4.34 (4.29) | 3.50 (2.99) | 14.25 (12.23) | 13.29 (8.43) | 3.75 (4.13) | 8.95 (9.00) | 6.43 (7.51) |
| Postnicotine concentration (ng/mL) | 11.79 (14.07) | 22.25 (18.62) | 10.36 (7.34) | 16.03 (11.71) | 15.10 (9.86) | 17.27 (17.30) | 13.04 (9.36) | 15.12 (13.93) |
| Nicotine increase (ng/mL) | 8.69 (11.32) | 17.91 (17.19) | 6.86 (7.11) | 3.65 (3.14) | 1.81 (7.61) | 13.52 (15.30) | 4.52 (7.07) | 8.91 (12.61) |
| Average puff volume (mL) | 96.81 (51.61) | 123.34 (168.06) | 68.30 (64.11) | 51.08 (34.81) | 53.42 (25.26) | 110.93 (127.35) | 59.85 (48.62) | 84.40 (98.00) |
| Average puff duration (s) | 4.47 (1.52) | 4.07 (1.60) | 2.21 (0.78) | 1.84 (0.52) | 2.52 (0.90) | 4.26 (1.56) | 2.24 (0.81) | 3.21 (1.59) |
*
Mean (SD) unless noted otherwise.
CO, carbon monoxide; FTND, Fagerström Test for Nicotine Dependence; M, menthol; PG/VG, propylene glycol/vegetable glycerin; T, tobacco.