Prevalence of past 6-month combustible tobacco use at 6 and 12-month follow-ups by baseline e-cigarette ever use among baseline never smokers
| Use in the prior 6 months | Baseline e-cigarette use | Difference in prevalence rates | |||
| Overall (n=2185) | Never use (n=1994) | Ever use (n=191) | % (95% CI) | P value | |
| 6-month follow-up | |||||
| Any combustible tobacco product, n (%)* | 90 (7.1) | 64 (5.5) | 26 (23.2) | 17.7 (9.8 to 25.6) | <0.001 |
| Combustible cigarettes, n (%)† | 63 (4.9) | 43 (3.7) | 20 (17.9) | 14.2 (7.0 to 21.4) | <0.001 |
| Cigars, n (%)‡ | 15 (1.2) | 11 (0.9) | 4 (3.6) | 2.7 (−0.8 to 6.2) | 0.014 |
| Hookah, n (%)§ | 33 (2.6) | 22 (1.9) | 11 (9.9) | 8.0 (2.4 to 13.6) | <0.001 |
| Number of different combustible tobacco products, n (%)† | <0.001 | ||||
| 0 | 1185 (92.9) | 1099 (94.5) | 86 (76.8) | ||
| 1 | 72 (5.6) | 55 (4.7) | 17 (15.2) | ||
| 2 | 15 (1.2) | 6 (0.5) | 9 (8.0) | ||
| 3 | 3 (0.2) | 3 (0.3) | 0 (0.0) | ||
| 12-month follow-up | |||||
| Any combustible tobacco product, n (%)¶ | 141 (13.8) | 101 (10.8) | 40 (44.4) | 33.6 (23.1 to 44.1) | <0.001 |
| Combustible cigarettes, n (%)¶ | 118 (11.5) | 85 (9.1) | 33 (36.7) | 27.6 (17.5 to 37.7) | <0.001 |
| Cigars, n (%)** | 18 (1.8) | 14 (1.5) | 4 (4.4) | 2.9 (−1.4 to 7.2) | 0.042 |
| Hookah, n (%)** | 47 (4.6) | 35 (3.8) | 12 (13.3) | 9.5 (2.3 to 16.6) | <0.001 |
| Number of different combustible tobacco products, n (%)¶ | <0.001 | ||||
| 0 | 884 (86.2) | 834 (89.2) | 50 (55.6) | ||
| 1 | 106 (10.3) | 74 (7.9) | 32 (35.6) | ||
| 2 | 28 (2.7) | 21 (2.2) | 7 (7.8) | ||
| 3 | 7 (0.7) | 6 (0.6) | 1 (1.1) | ||
*n=1276.
†n=1275.
‡n=1273.
§n=1270.
¶n=1025.
**n=1023.