This startling statistic was announced by Tai Hing Lam MD when giving a presentation to the recent 15th World Conference on Tobacco or Health held in Singapore on 11th June 2012.
Smoking is a well established risk factor of premature death. However, most studies primarily relied on middle-aged adults. And also, until recently, these studies had only covered different diseases, risks and outcomes, but none had researched the data on what’s called All Cause Mortality – that’s the data available for death from all causes in a population – not just illness (without death), and not just for known smoking related diseases.
However, earlier this year, Gellert et al, conducted a meta analysis called, “Smoking and All Cause Mortality in Older People”, which focused on elderly people (≥60 years), not middle aged adults – that’s their definition of ‘elderly’ not mine!
A meta analysis is a study where the researchers collect together all the results of all the most reliable studies and research that has been done on a particular topic, and work out what the big picture really is. It’s a systematic review of all the reputable data, and should give a better overall idea of what is really going on.
And what they found was dramatic. We all know that smoking kills, but it kills someone else, right? Wrong.
1. Most smokers underestimate their own risks.
2. Many older smokers mistakenly believe that they are too old to quit and gain any benefit
3. Some smokers mistakenly believe that quitting itself could be harmful if they see deaths of old friends who had quit recently
4. Many smokers look at the few (lucky) people who have smoked all their lives, and yet have not got any nasty diseases, and think this means that they themselves are somehow immune
The researchers point out that this meta-analysis could under-estimate the true risks of smoking. This is because many smokers in some populations, especially those from Asia, often only start smoking later in life than smokers in the West. Therefore, they had not smoked for as many years as those in the United States and United Kingdom. That would tend to cause an under-estimation of the real risks of life long smoking, because smokers and research from all countries had been included in the data collection for this study.
This is what that Total Mortality Meta Analysis found:
RR is short hand for Relative Risk (see below). Based on 17 different cohort studies from 7 different countries, the
- RR for current smokers overall was 1.85
- RR for 60 to 69 years was 1.94
- RR for 70 to 79 years was 1.86
- RR for 80 years or older was 1.66
What does that mean? Statistics are not easy for anyone to get your head around, but I’ll try and explain:
The Concept of Absolute Risk vs Relative Risk
Absolute risk is any one person’s risk of something happening to them. It’s a direct measurement. These risks are not compared to any other risk: they are just the probability of something occurring. For example, the absolute risk of getting heads when you toss a coin is 50%. It’s also 50% for getting tails, or 1 in 2 chance. It stands on its own with no other sort of risk factored into it, or compared with it.
Relative Risk (RR) is a comparison between different levels of risk. In health statistics, it is usually a comparison of one population with a particular disease, compared to a similar group of people who do not have the disease.
In smoking, the relative risk is therefore your risk (as a smoker) compared to the risk of similar people who do not smoke. In this particular study, they looked at your Relative Risk of dying from smoking.
Relative risk is not the same as your Absolute Risk. Relative Risk compares the Absolute Risk of different 2 different groups of people: those people with the disease compared to those people without the disease. In other words:
Relative Risk compares
- the Absolute risk of a disease (or death) in exposed people (smokers) to
- the Absolute risk of a disease (or death) in un-exposed people (non smokers).
Because of something called The Attributable Fraction (I’ll take their word for it), the above results indicate the Relative Risk of Death from smoking is actually 1:2, with slight variation depending on your current age. This Relative risk can also be expressed as a ratio e.g. 1:2, or as a percentage 50%.
In other words, 1 in 2 smokers will die from their smoking, i.e. 50% of smokers will die (of something/anything) as a result of their smoking, one way or another, in the end.
But it ‘s not all bad news. The researchers also investigated the benefits of quitting.
Risk Reduction Gained From Quitting
The Risk Reduction from Quitting was calculated by Gellert et al, to be
- 21% for 60 to 69 years
- 27% for 70 to 79 years
- 24% for 80 years or older
Plus: those who quit before age 40 years, or well before, avoid most of the excess risk associated with smoking.
The above benefits of quitting are underestimated because some former smokers might have quit because of ill health, and hence would die more quickly than continuing smokers.
Dr Huan went on to say,
“For unknown reasons, such information and warning cannot be found in many websites to help smokers quit. Existing pictorial warnings also do not show or highlight this risk. The 1 in 2 risk has never been used as a key campaign message until recently.
In 2011, Ireland was the first country to use 1 in 2 for a major social marketing campaign resulting in wide media coverage and great increases in calls to the Quitline and demand for smoking cessation services.
For public health information and education, the great death risk of 1 in 2 to 2 in 3 should be highlighted consistently and widely. This warning could be placed on cigarette packages so that all smokers know that they are betting their lives on the toss of a coin”
The earlier World Health Organization statement “Tobacco kills up to one in every two users” of 2008, was based on a 1994 study by R. Peto who stated
“about half of teenagers who keep smoking steadily will eventually be killed by tobacco (about a quarter in old age plus a quarter in middle age).” This is based on the translation of the RR of 2 in the British doctor cohort with 40 years of follow-up.
This risk was underestimated, since results from the 50-year follow-up of that same group of British doctors, showed even greater risk of dying from smoking than the 40 year follow up:
that if smoking started at a young age, 2 in 3 smokers will be killed by smoking.”
The Messages Are Clear
- Smoking Kills
- 50% of Smokers Will Be Killed by Smoking (at least)
- The benefits of Quitting are real and worth having
- It’s never too late to Quit Smoking and get health benefits.
Gellert C, Schöttker B, Brenner H. Smoking and all-cause mortality in older people: systematic review and meta-analysis. Arch Intern Med. 2012;172(11):837-844
Howell F.HSE Social Marketing Working Group on Tobacco. 1 in every 2 smokers will die of a tobacco related disease: can you live with that? quit. Presented at: 15th World Conference on Tobacco or Health; Singapore; March 20-24, 2012
Peto R. Smoking and death: the past 40 years and the next 40. BMJ. 1994;309(6959):937-939
World Health Organizaiton. WHO Report on the Global Tobacco Epidemic, 2008: The MPOWER Package. Geneva, Switzerland: World Health Organization; 2008