On 2018 Jan 26, Benjamin W Chaffee commented:

We appreciate the detailed reading of our publication.

In response, we note that a risk factor need not account for the majority of cases to be an important public health concern. Of all drivers involved in fatal traffic accidents in the United States, 79% were not impaired by alcohol.[1] Nonetheless, drinking and driving demands public health attention because of its indisputable and preventable contribution to traffic fatalities.

All risk factors for youth smoking that can be addressed through effective public policy merit attention, particularly if those factors are increasing in prevalence.

[1] National Highway Traffic Safety Administration. Traffic Safety Facts 2012 Data. DOT HS 811 870. https://crashstats.nhtsa.dot.gov Impaired by alcohol defined as blood alcohol concentration 0.08 or above.

On 2018 Jan 18, Brad Rodu commented:

Using youth data from Waves 1 and 2 of the Population Assessment of Tobacco and Health (PATH) survey, Watkins et al. reported that “[a]ny use of e-cigarettes, hookah, noncigarette combustible tobacco, or smokeless tobacco was independently associated with cigarette smoking 1 year later. Use of more than 1 product [polyuse] increased the odds of progressing to cigarette use.”

Watkins et al. focused almost exclusively on odds ratios, which is problematic because the size of the referent group of never tobacco users at Wave 1 (n= 9,058) is 36 to 97 times the size of the other tobacco use groups. This obscures the relative contributions of the groups to the outcomes, but they can be estimated using baseline numbers and adjusted odds ratios (Model 4) from eTable 10:

219 = 9058x + 255(2.12x) + 189(2.15x) + 114(3.08x) + 93(1.53x)

Of the 219 subjects reporting cigarette use in the past 30 days at follow-up, the numbers (percent) from each mutually exclusive tobacco-use group at baseline are: 175 never users (79.9%), 11 e-cigarette-only users (5.0%), 8 hookah-only users (3.7%), 7 other combustibles-only users (3.2%), 3 smokeless-only users (1.4%), and 15 polyusers (6.8%). These numbers are derived from the adjusted odds ratios and may vary slightly from the actual survey numbers, but the relative contributions of the groups will not change.

While teens who try one tobacco product are more likely to try another, the dominant gateway to cigarettes in the PATH youth survey was from no previous tobacco use.

Disclosure: BR is supported by unrestricted grants from tobacco manufacturers to the University of Louisville and by the Kentucky Research Challenge Trust Fund.

On 2018 Jan 18, Brad Rodu commented:

Using youth data from Waves 1 and 2 of the Population Assessment of Tobacco and Health (PATH) survey, Watkins et al. reported that “[a]ny use of e-cigarettes, hookah, noncigarette combustible tobacco, or smokeless tobacco was independently associated with cigarette smoking 1 year later. Use of more than 1 product [polyuse] increased the odds of progressing to cigarette use.”

Watkins et al. focused almost exclusively on odds ratios, which is problematic because the size of the referent group of never tobacco users at Wave 1 (n= 9,058) is 36 to 97 times the size of the other tobacco use groups. This obscures the relative contributions of the groups to the outcomes, but they can be estimated using baseline numbers and adjusted odds ratios (Model 4) from eTable 10:

219 = 9058x + 255(2.12x) + 189(2.15x) + 114(3.08x) + 93(1.53x)

Of the 219 subjects reporting cigarette use in the past 30 days at follow-up, the numbers (percent) from each mutually exclusive tobacco-use group at baseline are: 175 never users (79.9%), 11 e-cigarette-only users (5.0%), 8 hookah-only users (3.7%), 7 other combustibles-only users (3.2%), 3 smokeless-only users (1.4%), and 15 polyusers (6.8%). These numbers are derived from the adjusted odds ratios and may vary slightly from the actual survey numbers, but the relative contributions of the groups will not change.

While teens who try one tobacco product are more likely to try another, the dominant gateway to cigarettes in the PATH youth survey was from no previous tobacco use.

Disclosure: BR is supported by unrestricted grants from tobacco manufacturers to the University of Louisville and by the Kentucky Research Challenge Trust Fund.

On 2018 Jan 26, Benjamin W Chaffee commented:

We appreciate the detailed reading of our publication.

In response, we note that a risk factor need not account for the majority of cases to be an important public health concern. Of all drivers involved in fatal traffic accidents in the United States, 79% were not impaired by alcohol.[1] Nonetheless, drinking and driving demands public health attention because of its indisputable and preventable contribution to traffic fatalities.

All risk factors for youth smoking that can be addressed through effective public policy merit attention, particularly if those factors are increasing in prevalence.

[1] National Highway Traffic Safety Administration. Traffic Safety Facts 2012 Data. DOT HS 811 870. https://crashstats.nhtsa.dot.gov Impaired by alcohol defined as blood alcohol concentration 0.08 or above.