Jane Brody falsely reported in her November 12 New
York Times “Personal Health” column that, according to the National Survey on
Drug Use and Health (NSDUH), the smoking prevalence among young adults (age
18-25 years) is 40% (here). The error was picked up by the
American Council on Science and Health (here), and the Times later posted a correction, noting that the rate is 34%. (The
original number was the prevalence of all tobacco use, rather than the
prevalence of smoking.)
But is 34% the accurate figure? Perhaps; it depends on which federal survey
is used.
Anti-tobacco forces have for years selectively used
two sets of numbers based on two federal surveys in a manner that recalls the
schoolyard taunt, “Are you bragging or complaining?” When zealots brag about how regulation,
legislation and litigation have driven down smoking rates, they use the
CDC-supported National Health Interview Survey (NHIS). According to the 2010 NHIS, the prevalence of
smoking among young adults (18-24 years) was 20% (here). But when they complain that smoking
rates are too high, and demand more regulation, legislation and litigation,
they use the NSDUH, which produces higher estimates than NHIS – in this case
34%.
Why does this matter? Using Jane Brody’s corrected percentage from
NSDUH, the number of young adult smokers (18-24 years) in the U.S. is
10,489,854; using NHIS, the number is 6,165,090.
With respect to variability, this difference of 4.5
million smokers is huge, and here’s why.
NSDUH estimates are higher because it counts as a
smoker anyone who answers “yes” to this question: "During the past 30
days, have you smoked part or all of a cigarette?” The comparable question in the NHIS is, "Do
you now smoke cigarettes every day or some days?"
I published a formal study of this problem in 2009 (abstract
here), and I wrote a blog post about it (here). At that time, I calculated that there
were 9 million more smokers of all ages nationally in NSDUH compared with NHIS.
How can the federal government develop effective
policies to help American smokers when the government can’t even develop and
employ consistent estimates of how many Americans smoke?
I am grateful to Jane Brody for bringing attention
to this egregious problem.
1 comment:
This is an ongoing issue that still hasn't grabbed the attention of researchers and practitioners. What are seemingly minute discrepancies in questioning across surveys clearly leads to big differences - in the case of NSDUH vs. NHIS, 14% points! I wonder what the prevalence rates would look like if the NSDUH used a combination of two questions like the CDC - ironically, the NSDUH actually includes the same question as the NHIS that asks whether a respondent has smoked 100 cigarettes in their lifetime, yet it is not used to define current smoking. Like your 2009 study, Ryan et al. (http://www.hindawi.com/journals/jeph/2012/918368/) also explore prevalence rates using 2008 NSDUH and NHIS data, noting that certain subpopulation estimates become comparable when using a modified NSDUH smoking definition. Why SAMHSA does not adopt this more comparable definition remains a mystery.
Another frequently unmentioned issue is what I call the prevalence smokescreen: although prevalence rates have dropped over the past several decades, this is actually due to population growth. In fact, the absolute number of smokers has remained relatively stable, but unfortunately, many folks in public health still attribute this reduced prevalence to the success of anti-smoking campaigns and programs. Not to say these sorts of efforts are frivolous, but it's clear that there's more than meets the eye.
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