Would You Believe 40 Percent?

Remember that unpublished study claiming that a smoking ban in Helena, Montana, cut heart attacks in half? It has now been published—in the British Medical Journal, no less. Along the way, the authors' confident assertions have become much more cautious.

Last year Stanton Glantz, the California anti-smoking activist who helped prepare the study, said it showed that "banning secondhand smoke...immediately starts saving lives." Richard Sargent, a local physician and smoking ban proponent who was the lead author, said Helena's ordinance "led to an immediate and dramatic decline in the number of heart attacks."

By contrast, the published study concludes that "laws to enforce smoke-free workplaces and public places may be associated with an effect on morbidity from heart disease." Sargent et al. cite "Helena's small size" (and the correspondingly tiny numbers of heart attacks seen there each month) as "an important limitation of the study." They note that a before-and-after study such as this one cannot prove causation, since "there is always the chance that the change we observed was due to some unobserved confounding variable or systematic bias." And they concede that "we did not make any direct observations to measure how much the exposure to secondhand smoke was reduced during the months when the law was enforced."

Another striking change: The 60 percent drop that Sargent et al. attributed to the ban last year has become a 40 percent drop—a number that is still preposterously large, even if you accept the anti-smoking movement's claims about the effects of secondhand smoke. As I noted last year, the American Heart Association blames secondhand smoke for about 5 percent of heart disease deaths.

"The effect associated with the smoke-free law may seem large," Sargent et al. admit. But they claim it is consistent with epidemiological research indicating that exposure to secondhand smoke is associated with a 30 percent increase in heart attack risk (a number that is itself implausibly high, since smoking, which involves much higher levels of exposure, is associated with a heart disease risk increase of about 70 percent). "If all this effect were to occur immediately," Sargent et al. write, "we would expect a fall of –.30 X 40.5 = –12.2 in admissions during the six months the law was in effect, which is within the 95% confidence interval for the estimate of the effect (a drop of –32.23 to –0.8 admissions)."

Here Sargent et al. make a calculation error that someone at the BMJ should have caught. If secondhand smoke increased the incidence of heart attacks by 30 percent, and if this effect could be reversed immediately, and if Helena's ban completely eliminated secondhand smoke (which it didn't, since it did not apply to private residences), the drop would be 23 percent, not 30 percent, meaning nine fewer heart attacks rather than the 12 that Sargent calculate or the 16 that they report. Notice, too, how wide the confidence interval is, ranging from less than one to more than 32, which reflects the small sample size.

Hedging their bets, Sargent et al. note that a smoking ban not only reduces exposure to secondhand smoke; it also encourages smokers to quit or cut back. "While both of these effects are probably occurring," they say, "we do not have a large enough sample size to estimate their relative contribution to our results." In other words, the reduction in heart attacks could have occurred partly or entirely among people who stopped smoking because of the ban, in which case it might have nothing to do with secondhand smoke—a pretty important concession given the way anti-tobacco activists (including Glantz's friends at Americans for Nonsmokers' Rights) are using the study to push for more smoking bans.

But even if Helena's ordinance caused every smoker in town to quit (which it assuredly didn't), it still could not possibly be responsible for a 40 percent drop in heart attacks, unless smoking's contribution to heart disease is twice what the CDC says it is. An immediate 40 percent drop in heart attacks across the whole population also implies a much more dramatic effect than is seen in studies of people who quit smoking.

Sargent et al.'s final defense is that the numbers are unimportant. Co-author Robert Shepard, another local physician and smoking ban advocate, told the Helena Independent Record: "I've said all along that it doesn't matter whether the drop is 60 or 80 or 40 percent. The important thing is, the drop isn't zero." Sargent added: "What's the right answer? I don't know. I can tell you with confidence that it's between 24 and 87 percent."

It's a mystery where those numbers came from. But does Sargent really think it's possible that secondhand smoke, smoking, or both together account for something like nine out of 10 heart attacks? "It will take four or five studies to figure it out," he said, "and they will have to be done in communities bigger than Helena." They will also have to be done by researchers who are interested in finding the truth, as opposed to ammunition for their cause.

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  • ||

    I still don't understand why that is.


    Take a look on any given piece of earth and count how many butts you see, especially at the beach or on the sidewalks. The other day, I saw a guy dump his whole car ashtray onto the parking lot of a Starbucks.

    At least, this is what gives me a little sympathy for the anti-smoking crowd. However, the anti-prohibition part of me keeps me biased against their crusade.

  • Mo||

    s.a.m.
    If anti-smoking initiatives focused on the litter, you'd probably have quite a few smkers in your circle as well. Using made up health statisitics and "for the children" arguments to prevent litter is a weak, passive-aggressive way of stopping the problem. Fine people for littering because it sure as hell isn't limited to smokers. I saw a guy throw out his fast foor bags in a parking lot before, but that doesn't make me sympathetic to anti-fast food activists.

  • ||

    I think Jacob conflates chronic heart disease caused by long term exposure to second hand smoke (the subject of the CDC's figures) with the inducement of an acute condition - a heart attack - in people who already have heart disease, brought on by an incident of breathing air fouled with the nasty stuff in second hand smoke (the subject of the Helena study).

    Good catch on the calculation error, though.

  • ||

    Even though the study is obviously meaningless, there's nothing that will undo the damage done by the fact that newspapers were willing to promote this sort of absurdity and that they will, no doubt, not bother to report that most of what was said was essentially false. If Phillip Morris came out today with a study that "proved" that cigarettes are actually not responsible for any illnesses, and then that study was shown to be as invalid as this one is at a later date, guess which side of the study the news would show? The anti-smoking side, of course. I still don't understand why that is.

  • ||

    Somebody should do a study of monomania.

  • ||

    Irrespective of whether the data is correct, second hand smoke has virtually been eliminated from the workplace, unless one works in a nightclub or bar.

    Rather than fight it, I'm working on a a false study to prove that second hand farts are dangerous, and must be removed from the workplace. And I don't want all you flatulators blocking the front entrance, either.

  • Fort Liberty||

    This reminds me of one of my favorite jokes:

    "Did you know that 50% of all American school children have a below-average reading level?"

  • ||

    Might I suggest an update?

    "Did you know that 50% of Americans have below-average math skills?"

    "That can't possibly be true!"

  • Michael J. McFadden||

    If you visit bmj.com and look below the stack of blue menu items you will find the link for ONLINE studies that will take you to the April 5th "Reduced Incidence..." Helena study.

    Click on "Abstract" and then click on "Read Responses" to see the study soundly criticized.

    While there are a number of legitimate scientific criticisms of the study itself, I firmly believe (and responded at the BMJ) that the most important fact about this study is that it clearly and without possible argument shows the outright fraud perpetrated by the Antismoking Crusade when it comes to secondary smoke.

    Many prominent figures in the Antsmoking community came out during the past year with declarations that this study proved and/or affirmed the "deadliness" of secondary smoke. The study itself, now that it has been made public, clearly states that it SPECIFICALLY did NOT examine the effect of secondary smoke on nonsmokers because it would have shown NO RESULTS.

    Even the CEO of the American Heart Association, M. Cass Wheeler, came out in a press release titled (in big bold print) �NEW STUDY LINKS SECONDHAND SMOKE TO HEART ATTACKS� with the statement that �Banning smoking is the only logical response to the scientific evidence concerning the dangers of secondhand smoke."

    Doing a study and then encouraging and promulgating fraudulent statements about the contents of that study for over a year in order to force the passage of laws in frightened communities should be treated as an outright crime and those responsible for it held to full account.

    Michael J. McFadden
    Author of "Dissecting Antismokers' Brains"
    http://www.Antibrains.com

  • ||

    Someone should, indeed, do a study on monomania. Those who monomanically attempt to contradict the growing scientific evidence that secondhand smoke harms health would be excellent subjects.

    Your right to swing your fist ends where my nose begins. So does your right to spread poison.

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