Smoking is even more dangerous than we realised

The UK government has finally decided to push ahead with legislation on plain packaging for cigarettes before the general election in May. This comes after years of inexcusable delay and extensive lobbying by the tobacco industry. In a brazen attempt to bully the government, the tobacco companies have even threatened to sue for damages if such legislation is introduced. Plain packaging is already required in Australia (and is now being introduced in Ireland) and has been shown to be an effective anti-smoking measure (evidence of which can be found here, here, here and here).

We are all fully aware that smoking is one of the most dangerous activities that you can do, but recent work has emphasised just how dangerous. Two studies (one in the New England Journal of Medicine, the other in BMC Medicine) have shown that smoking is associated with more diseases than previously thought, and plays a role in far more deaths. The first study was carried out in Australia, and followed over 200,000 people for 4 years to assess the effect of smoking on their lifespan. This was a well carried out, prospective study (see below for explanation). They found that death rates in smokers were 3-times higher than in non-smokers, and that smokers die an average of 10 years before their non-smoking counterparts. Furthermore, up to 67% of deaths in smokers can be attributed to their habit. To put it simply, for every three people you see smoking outside a pub, two of them will eventually die from a smoking related illness if they don’t quit. It’s a shocking toll.

The second study was a meta-analysis (see below for explanation) of 5 previous US studies, including nearly a million people. They showed that at least 30 diseases are associated with smoking, including cancers of almost every site (pancreas, bladder, breast, kidney…). It’s a terrifying list, which I have included below, but there is some good news. The BMC Medicine study confirmed that if somebody stops smoking, not only will the damage stop accumulating, but the body can begin to heal itself. The earlier the smoker quits the better, and those who quit early have the same lifespan as non-smokers.

These studies emphasise the need for continued efforts to reduce the levels of smoking. Measures such as the plain packaging of cigarettes, and the banning of smoking in cars are positive steps. The UK government’s vote on the issue before will take place before May, so hopefully there will be progress soon. Fingers crossed.

Diseases associated with smoking

Laryngeal cancer – 103.8 times more likely to die from than non-smokers

Lung cancer – 22.9

Lip and oral cavity cancer – 5.6

Oesophageal cancer – 5.1

Urinary bladder cancer – 3.9

Pancreatic cancer – 1.9

Liver cancer – 1.8

Stomach cancer – 1.7

Colorectal cancer – 1.6

Breast cancer – 1.3

Kidney and renal pelvis cancer – 1.2

Acute myeloid leukaemia – 1.1

Rare cancers – 1.1

Cancers of unknown site – 2.7

Chronic obstructive pulmonary disease (COPD) – 25.0

Aortic aneurysm – 10.1

Ischemic disorders of the intestine – 6.1

Other arterial disease – 5.6

Ischemic heart disease – 3.0

Liver cirrhosis – 2.6

Infection – 2.5

Hypertensive renal disease – 2.4

Unknown causes – 2.2

Stroke – 2.1

Atherosclerosis – 2.1

Other digestive diseases – 2.1

Additional rare causes – 2.0

Other heart disease – 1.9

Pneumonia, influenza, and TB – 1.9

Hypertensive heart disease – 1.9

Other respiratory diseases – 1.9

Renal failure – 1.9 Diabetes – 1.5

Further Explanation

Prospective study: This is the gold standard of medical studies. In a prospective study, people are recruited to look specifically at a certain thing (in this case, the effect of smoking on lifespan). The study is planned ahead of time, and controls are put into place to ensure the highest quality data. This differs from a retrospective study, where data that has already been gathered is analysed to draw conclusions about a certain outcome. This type of study can be prone to significant bias, because unlike a prospective study, you cannot control the population you are studying. It is also more difficult to separate correlation from causation using a retrospective study. It is far easier and cheaper than a prospective study however, and very often the only option.

Meta-analysis: This type of study involves the combining of several studies in the hope of revealing patterns in the results of those studies. A meta-analysis allows the study of far larger numbers of people, but can be severely affected if one or more of the individual studies is poorly carried out.

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