Benefits of quitting smoking
Compared to never-smokers, long-term daily cigarette smokers suffer higher early mortality from smoking-induced diseases. Ex-smokers have a longer average survival than continuing smokers. Particularly convincing evidence comes from a longitudinal study of UK male doctors. It was found that the mortality of the smokers was almost double that of never-smokers and that COPD was 13 times more prevalent and lung cancer 15 times more prevalent among smokers compared with never-smokers. After a 50-year observation period it was concluded that smokers die about 10 years younger than nonsmokers. Cessation at ages 60, 50, 40 or 30 years results in gains of about 3, 6, 9 or 10 years of life expectancy, respectively. The effect of smoking cessation on the rate of decline of FEV1 is illustrated schematically in figure 2 .
|OR (95% CI)||1-year quit rate %|
|High-dose nicotine patch||2.3 (1.7–3.0)||26.5|
|Nicotine gum (more than 14 weeks)||2.2 (1.5–3.2)||26.1|
|Patch + ad libitem nicotine replacement therapy||3.6 (2.5–5.2)||36.5|
|Patch + BupropionSR||2.5 (1.9–3.4)||28.9|
|Patch + inhaler||2.2 (1.3–3.6)||25.8|
Table 2 – Efficacy of first-line drugs for smoking cessation. Meta-analysis of data from placebo-controlled trials in smoking cessation reporting 1-year quit rates with the above drugs for smoking cessation used for 3 months in combination with counselling. The comparator is the placebo arm without drug but with counselling. The results are shown as odds ratios (OR) with 95% confidence intervals (CI) and as % of subjects who have stopped smoking at 1 year; OR is the proportional increase in quit rate compared to placebo (for example, with varencicline the average quit rate was 3.1 times that with placebo). Modified from Fiore et al., 2008.
To prove a causal relationship between smoking cessation and health benefits, an intervention study is necessary where smokers quit and outcome is observed. One of the best studies is the US Lung Health Study, a large randomised controlled trial in 5587 patients with mild COPD, which showed that repeated smoking cessation during 5 years resulted in a quit rate of 37%, and after 14.5 years the quitters had appreciably better lung function and a higher survival rate compared with those who continued to smoke. In another study, the quality of life of patients with moderate or severe COPD 1 year after quitting was significantly better than that of continuing smokers.