Tobacco threat still smokes like a dormant volcano

In 2006, I found myself caught within a crowd of 267,153 fellow New South Welshmen. No, it was not at a one-day cricket match or even a State of Origin rugby league clash.

All of us were aged 45 years or above — considerably above in my case. We comprised the subjects for a long-term survey from the Sax Institute, a public health research agency in Sydney, known as the 45 and Up Study.

It is technically described as a “cohort study randomly sampled from the general population of NSW”.

We all completed a health questionnaire and gave our consent to be followed by repeat surveys and linkage of our health databases. 

We were asked if we had ever been a regular smoker, at what age we started (if we had), when we quit (if we had) and how much we had smoked. At baseline, 7.7% of respondents (aged 38.5 years on average) said they were current smokers and 34.1% were past smokers. 

With a mean follow-up time of 4.3 years, there had been 5593 deaths. This was a frightening intimation of mortality for those of us in the study.  

When adjusted for other risk factors, current smokers vs never-smokers had about three times the risk of dying — a risk that increased with the heaviness of the smoking habit. “Smokers were estimated to have the same risks of death [about 10] years earlier than 75-year-old nonsmokers,” the study found.

The good news was that “for those smokers who quit before age 45, the death rates were similar to those seen in never-smokers. Mortality diminished progressively with increasing time since cessation of smoking”.

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The research team was led by Professor Emily Banks from the National Centre for Epidemiology and Population Health in Canberra and the Sax Institute. Renowned Australian epidemiologist Dame Valerie Beral from the Cancer Epidemiology at the University of Oxford was also part of the research group. The results were recently published in the journal BioMed Central.¹ 

"A mature epidemic of tobacco use is not a picnic ground any more than the side of a seemingly quiescent volcano. People who live near tobacco still die."

Dame Valerie has a serious track record for studying the health of women, especially using cohort studies similar to this one. The idea of such a study is to begin tracking people while they are well. Then when an illness befalls them, it’s easy to compare their prior history with that of a person who has remained well, looking for subtle differences in lifestyle, medications, occupation and so forth.  

The great virtue of cohort studies is the absence of bias in the selection of the study subjects. This makes the comparison of individuals years down the track easier: the researcher and the subject are blind at the start to the possible outcomes.

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The Sax team concluded that “up to two-thirds of deaths in current smokers can be attributed to smoking. Cessation reduces mortality …the earlier in life [the] greater [the] reduction”.

For those with an epidemiological bent, the study authors argue that smoking in Australia manifests characteristics of a mature epidemic. 

A mature epidemic is rather like a volcano on heavy doses of diazepam: low rate of current smoking; long duration and stable intensity of smoking among those who smoke; young and stable age of commencement; high prevalence of past smoking; and similar levels of relative risk from smoking in successive birth cohorts.

A mature epidemic of tobacco use is not a picnic ground any more than the side of a seemingly quiescent volcano. People who live near tobacco still die. And don’t kid yourself that it will never blow.

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Yes, we have made immense gains in tobacco control. Most people who quit smoking we know do so on their own — impressed, I imagine, by the overwhelming evidence about its harm. But quitting becomes easier if society does not tell people attractive lies about tobacco. Thank goodness we no longer advertise tobacco and so diminish the risk of seduction and deception.

But every smoker who can be urged and helped to quit smoking, when seen in general practice for example, is potentially a life saved.  

They are saved not only from death but also from a huge amount of suffering, and studies such as 45 and Up confirm that if you quit, the results are good.

Professor Leeder is an emeritus professor of public health and community medicine at the Menzies Centre for Health Policy at the University of Sydney. He is also editor-in-chief of the Medical Journal of Australia.

 

Published in Australian Doctor 11th March 2015