Table 1.
Participant Characteristics
| Variable | Control Participants (n = 114) | ENDS Users (n = 164) | Cigarette Users (n = 117) | P Valuea (Group Effect) | Pairwise Comparisons |
|---|---|---|---|---|---|
| Demographics | |||||
| Age, y | 30.8 ± 11.9 | 27.4 ± 10.6 | 42.8 ± 13.8 | < .001 | S > C > E |
| Female sex | 57 (50.0) | 64 (39.0) | 52 (44.4) | .190 | NA |
| Race or ethnicity | < .001 | ||||
| Black | 5 (4.4) | 4 (2.4) | 47 (11.9) | S > C, E | |
| White | 79 (69.3) | 141 (86.0) | 65 (55.6) | E > C > S | |
| Other | 30 (26.3) | 19 (11.6) | 14 (12.0) | C > E, S | |
| Nicotine-containing product use measurements | |||||
| Exhaled carbon monoxide, ppm | 0.00 (1.00) | 0.00 (1.00) | 18.00 (17.00) | < .001 | S > C, E |
| Serum cotinine, ng/mLb | 1.99 (0.00) | 179.00 (166.00) | 213.50 (157.00) | < .001 | S, E > C |
| Serum nicotine, ng/mLb | 1.99 (0.00) | 1.99 (1.01) | 1.99 (2.76) | < .001 | S > E > C |
| Urinary nicotine, ng/mL | 0.00 (0.00) | 4.00 (4.00) | 5.00 (4.00) | < .001 | S > E > C |
| Smoking history | |||||
| Years | 0.00 (0.00) | 0.00 (5.00) | 21.00 (24.00) | < .001 | S > E > C |
| Pack-y | 0.00 (0.00) | 0.00 (5.25) | 24.00 (25.00) | < .001 | S > E > C |
| Vaping history | |||||
| Years | 0.00 (0.00) | 4.00 (3.00) | 0.00 (0.00) | < .001 | E > S, C |
| Vaping-y | 0.00 (0.00) | 9.00 (11.00) | 0.00 (0.00) | < .001 | E > S, C |
| ENDS type | |||||
| Third generation | NA | 29 (18) | NA | NA | NA |
| Fourth generation | NA | 135 (82) | NA | NA | NA |
Data are presented as No. (%), mean ± SD, or median (interquartile range), unless otherwise indicated. For baseline measurements, we constructed a series of analyses of covariance models adjusted for age, sex, and race or ethnicity. To constrain the false discovery rate at 0.05, the Benjamini and Hochberg procedure was applied to the set of 24 tests of between-group differences before the product challenge in Table 2.28 C = control participants; E = electronic nicotine delivery system users; ENDS = electronic nicotine delivery system; NA = not available; ppm = parts per million; S = cigarette users.
Based on Kruskal-Wallis overall test for group differences in distribution for quantitative measures and χ2 tests for categorical measurements.
For these assays, the minimum value was coded as 1.99 when the concentration was less than the threshold of detection (< 2 ng/mL).