Monday, September 29, 2008

SHS kills . . . twice?

According to anti-smoker crusaders, secondhand smoke can kill you. But, can it kill you if you’re already dead? Are anti-smokers so callous that they would kill a smoker twice for the same crime?

The latest report from Health Canada has slashed Smoking Attributable Mortality (SAM), from 47,000 to 37,000, with the stroke of a pen. In addition, the new format provides some insight into how they calculated the 37,000 deaths attributed to smoking.

According to StatCan, there were 17,188 lung cancer deaths in Canada in 2002. Health Canada estimates that 13,401 of these deaths (9,028 male; 4,373 female) were directly attributable to smoking.

They base these numbers on something called a Smoking Attributable Fraction (SAF). For lung cancer, this fraction (88.6% for males; 62.5% for females) is then multiplied by the total number of deaths recorded by StatCan for the time period being studied. The result is the estimated Smoking Attributable Mortality.

The fractions are so implausibly high because they include former smokers, albeit at a lower relative risk. Smoking prevalence rates for males in the study was 26.3% for current smokers, and 44.6% for former smokers. Former smokers were identified as anyone who had smoked 100 or more cigarettes in their life time. Only 29.1% of the adult male population (15 years of age plus) was identified as non-smokers.

But, here’s another sticking point. The SAF for lung cancer due to exposure to SHS is 1.5% for males and 1.4% for females. If you multiply the total number of lung cancer deaths as recorded by StatCan mortality tables (10,195 males; 6,993 females) by the appropriate SAF you get approximately 252 lung cancer deaths allegedly caused by exposure to secondhand smoke.

But, the vast majority of lung cancer deaths (roughly 75%) had already been attributed to active smoking. So, were some deaths actually counted twice; once due to active smoking and once due to secondhand smoke?

If the SAF represents the number of non-smokers allegedly killed by secondhand smoke, shouldn’t the calculation be confined to deaths among the non-smokers who succumbed to lung cancer?

After all, the Health Canada report says quite clearly: “Passive-smoking-attributable mortality (PSAM), was derived by applying age and sex specific relative risk and rates of mortality from lung cancer and ischemic heart disease (IHD) to the population of Canadians who have never smoked but who are exposed to environmental tobacco smoke (ETS) from spouses and other sources.”

Now, a year or two back, I would have accepted the report from Health Canada without question. But, after reading about hurricane force winds required to clear secondhand smoke from bars, the serious hazards from SHS posed to minor passengers driving in a convertible with the top down, people dropping dead from heart attacks after 30 minutes of secondhand smoke exposure, the deadly effect of smoker’s breath on children, etc., etc., etc, I’m inclined to be a little more skeptical.

Maybe someone with the proper credentials will enlighten me.

And, maybe they can also enlighten me about the number of deaths from Ishemic Heart Disease (IHD) attributed to SHS exposure in the over 80 crowd. According to StatCan 2002 mortality tables, 21,179 Canadians past the age of 80 died from IHD. That’s 52% of all deaths from IHD.

Now, here’s what I need help understanding. The statistics show that the same SAF used to calculate deaths due to SHS was used for the under 45 group as was used for the over 80 group. This indicates that exposure to SHS occurred at similar smoking prevalence levels and exposure levels for both age groups.

But most Canadians retire at 65 years of age, thus eliminating exposure in the workplace. In addition, smoking prevalence declines with age, from .307 for males aged 44 years to .075 for males over 80. A similar reduction can be seen in the female population. Percentage wise, the reduction in smoking prevalence, and therefore spousal exposure, is 75% in both females and males, by the time they reach 80.

So, shouldn’t the reduced exposure to SHS in both the workplace and the home be taken into consideration?

And, just what kind of numbers game are they playing when they tell us that, out of 21,179 total IHD deaths after the age of 80, they can pinpoint 279 as being due to SHS exposure. And, even if they could, if those non-smoking 80-year olds exposed to SHS are living to the same ripe old age as those not exposed, how can anyone reasonably argue SHS is a hazard?

Maybe my interpretation of the statistics is wrong. And, maybe cows really can jump over the moon. But given the exaggerations and distortions coming from the anti-smoker brigade, it’s difficult to trust anything they say. Sadly, this lack of confidence also applies to Health Canada, at least as far as smoking related issues.

Statistics can be a wonderful tool. They can also be a powerful weapon in the hands of the propagandist intent on spreading fear in an unsuspecting population. Fear makes it easy for people to surrender the civil liberties of others, in the name of the public good. They seldom consider the fact that they might be the next target group of the hate mongers.

But, right now I need a break. Let’s see . . . two fingers of Gordon Highlanders and a smoke should just about do it. While they’re both still legal.

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