Table 4. Hazard Functions in Cumulative Percentages (and 95% CIs) for Age of Cigarette Initiation Outcomes by Sexa.
| Age, y | Initiation of ever cigarette use, % (95% CI) | Initiation of past 30-d cigarette use, % (95% CI) | ||
|---|---|---|---|---|
| Boys | Girls | Boys | Girls | |
| 12 | 0 | 0 | 0 | 0 |
| 13 | 1.2 (0.8-1.5) | 1.5 (1.1-1.8) | 0.4 (0.2-0.5) | 0.7 (0.5-0.8) |
| 14 | 2.8 (2.4-3.3) | 3.0 (2.6-3.5) | 1.1 (0.8-1.4) | 1.4 (1.1-1.7) |
| 15 | 5.0 (4.4-5.6) | 5.5 (4.8-6.2) | 2.0 (1.5-2.5) | 2.7 (2.3-3.2) |
| 16 | 8.8 (7.9-9.7) | 8.4 (7.5-9.3) | 4.3 (3.6-5.0) | 4.3 (3.7-4.9) |
| 17 | 16.2 (14.5-17.8) | 14.6 (13.3-15.9) | 9.4 (8.1-10.8) | 8.7 (7.7-9.8) |
| 18 | 27.4 (25.1-29.6) | 21.6 (19.8-23.5) | 19.0 (17.1-21.0) | 13.7 (12.2-15.2) |
| 19 | 35.7 (32.3-39.2) | 25.9 (23.1-28.7) | 24.7 (21.8-27.6) | 16.7 (14.4-19.1) |
| 20 | NA | 31.1 (24.7-37.7) | 30.0 (21.7-38.4) | 17.9 (12.1-23.8) |
| 21 | NA | NA | NA | 28.4 (14.4-42.4) |
Abbreviation: NA, not available.
a
Population Assessment of Tobacco and Health (PATH) Study data reprinted with permission from the United States Department of Health and Human Services.18 Restricted file received disclosure to publish: February 10, 2020; February 17, 2020; February 28, 2020; March 06, 2020; May 01, 2020.