We all know the phrase, “smoking kills.” Ever since the mid-1900s, doctors have been telling us of the many dangers associated with smoking tobacco, including increased mortality rates. The most influential of these studies, published in 1956, presented very strong evidence that over half of all smokers would one day die, due to complications from smoking. A newer study published in BMC medicine, claims that these mortality rates may be even higher, perhaps as a high as 66 percent. This means that two out of every three smokers will die from conditions caused by smoking, according to the research.
The National Centre for Epidemiology and Population Health at the Australian National University conducted the study in New South Wales, Australia. The study followed 204,953 men and women over the age of 45, and categorized them into three groups: smokers, past smokers, and never smokers – those who had never been a regular smoker, at any point.
During the study, researches found that the percentage of smokers was comparable between men and women. Current smokers were more likely to be younger than never smokers, and they were less likely to live in urban areas. Current smokers were also more likely to report consuming greater than 15 alcoholic beverages per week, and were more likely to have a higher body mass index, two factors which were accounted for when mortality rates were examined. They also had less education, and lower income than never smokers. Never smokers were more likely to hold private health insurance.
In epidemiological research studies, a term called person-years is often used. Person-years refers to the number of years studied for all participants added together; for example, a two-year study done on five people, would equal ten person years. In this study, a total of 874,120 person-years were examined, and 5,593 deaths occurred among the study population over those years.
Outcomes of these studies are usually reported in terms of relative risk, a term, which describes the proportion of risk of an outcome, due to a specific factor, examined in the study, such as smoking in this case. The study found that male and female smokers were 2.76 (male) and 2.95 (female) times more likely to die than never smokers. Past smokers were 1.27 (male) and 1.39 (female) times more likely to die than never smokers, which shows that quitting can greatly reduce the risk of death caused by smoking.
Researchers also took into account the number of cigarettes smoked daily. In participants who smoked 1-14 per day, there was a two-fold increase in mortality. In participants who smoked more than 25 per day, there was a four-fold increase in mortality. Both of these mortality rates were in comparison to never smokers.
As hinted to above, the study did show the quitting smoking, regardless of how late in life it happens, can greatly reduce the risk of death due to complications from smoking. In this study, researches found that in participants who had quit smoking between the ages of 45 and 54, their mortality rate was only 1.36 to 1.52 times higher than never smokers. As time passed and they kept away from the habit, these rates decreased even further.
As the first large-scale population study conducted on smoking in Australia, this will hopefully be eye opening to smokers. We all hear about how smoking kills, but when you see overwhelming evidence that 2 in 3 smokers will eventually die from smoking complications, it’s a sobering thought, one that hopefully will convince smokers to quit. It’s never too late, and the sooner one quits, the greater their risk of complications will decrease.