The
U.S. Centers for Disease Control and Prevention released selected information
from the 2015 National Youth Tobacco Survey in April 2016 (here). The agency cherry-picked numbers from
previous surveys to portray e-cigarettes as a threat to teens, while ignoring
sharp declines in teen smoking (here, here and here).
Last
month, the CDC released the underlying 2015 NYTS data, ending an eight-month
embargo that prevented analysis by independent investigators.
The
agency traditionally reports current smoking and vaping numbers separately, ignoring
dual use and wrongly suggesting that the numbers are independent. In contrast, here I report exclusive users of
these products as well as dual users. I also
add important findings that the CDC omitted.
The
chart shows current use (that is, on one or more days in the past 30) of
cigarettes and e-cigarettes among middle and high school students over the
four-year period. The CDC emphasized the
large increase in e-cig use from 2011 to 2015.
As I noted earlier (here),
the large spike from 2013 to 2014 was likely due to a change in the NYTS
questions. It is clear that the increase
slowed during the last year, but prevalence of exclusive e-cig use among high
schoolers still increased from 8.2 to
10.6%; dual use declined marginally from 5.2 to 5.0%. The prevalence of exclusive smoking among
high school students was flat at 4.0%.
Given
that the CDC has relentlessly asserted that e-cigarettes are a gateway to
smoking, it is unsurprising that the agency did not publicize responses to two
questions in the 2015 survey that focused on which products students used
first. I report here for the first time
how high school students answered these questions, comparing two groups of current
smokers: those who only smoked cigarettes and dual users of cigarettes and
e-cigs.
The
question, “Which of the following tobacco products did you try first?” produced
these results:
Table 1. Percentage of High School Current Exclusive Smokers and Dual Users Who Tried Various Tobacco Products First, NYTS 2015 | ||
---|---|---|
Product | Exclusive Smokers | Dual Users |
Cigarettes | 60.2% | 66.8% |
Cigars | 11.3 | 6.0 |
E-cigarettes | 6.5 | 8.7 |
Smokeless tobacco | 9.1 | 7.6 |
Hookah | 4.5 | 6.7 |
Other products | 1.1 | 2.6 |
Not sure | 2.9 | 1.3 |
Never tried any product | 4.4 | 0.3 |
All | 100% | 100% |
Percentages
in bold: Exclusive smokers
significantly different than dual users.
The
table shows that there were no significant differences between exclusive
smokers and dual users in the product first used. Most had tried cigarettes first (60% and 67%
respectively); the rest had chosen cigars, smokeless, e-cigs and other products. There is little evidence here for the CDC’s
claim that e-cigarettes are a gateway to smoking.
A
question about initiation further exposed the relationship between cigarette
and e-cigarette use. Here is how current
exclusive smokers and current dual users responded:
Table 2. Relationship of Cigarette and E-Cigarette Use Among High School Current Exclusive Smokers and Dual Users, NYTS 2015 | ||
---|---|---|
Response | Exclusive Smokers | Dual Users |
Never tried cigs or e-cigs | 16.4% | 1.8% |
Only tried cigs | 19.8 | 2.7 |
Only tried e-cigs | 0.5 | 1.9 |
Tried cigs before ever tried e-cigs | 48.7 | 77.2 |
Tried e-cigs before ever tried cigs | 14.6 | 16.4 |
All | 100% | 100% |
Percentages
in bold: Exclusive smokers
significantly different than dual users.
This
table shows that large majorities of high school current exclusive smokers and
dual users started with cigarettes. Only
15-16% of these students are even eligible to be considered gateway cases, in
which users moved from vaping to smoking.
There
are troubling inconsistencies in these tables.
For example, 16% of current exclusive smokers – who only used cigarettes
in the past 30 days – responded that they never tried cigarettes (Table 2). Four percent of exclusive smokers responded
that they had never used any tobacco product (Table 1).
The
“Y” in NYTS stands for youth, and responses from these surveys are known to be inconsistent. In working with the data, if one eliminates
participants who gave inconsistent responses, there would be considerably fewer
valid participants. I discussed this problem
in 2015 (here), when I called
on the CDC to “issue a comprehensive report on the internal consistency and relative
validity of the NYTS data.” The agency appears to have ignored that issue.
1 comment:
They should also have asked how many actually use nicotine in their ecigs.
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