Approved research

The hazards of smoking and benefits of cessation on cause-specific mortality in the UK by age, sex and social status.

Lay summary

Smoking remains a major cause of premature death worldwide. Despite a significant reduction in the frequency of adult smoking in high-income countries, about one-quarter of all deaths between 30 and 69 are still caused by smoking. Recent studies have shown the smokers who start early in life and don't quit can expect to save a full decade of life. In our previous study conducted using US NHIS data, we found that smokers lose at least one decade of life expectancy, as compared with those who have never smoked, and cessation before the age of 40 years reduces the risk of death associated with continued smoking by about 90%. Similar benefits of cessation on overall mortality were found in other studies. However, the absolute and relative risk reduction in clinically relevant subpopulations (e.g. among those who are diabetic, obese or hypertensive) remain unknown. Similarly, the benefits of cessation for different diseases, notably ischemic heart disease, stroke, various cancers and respiratory disease in subpopulations also remain unknown. Finally, the absolute and relative benefits of cessation might well differ by social status (or socioeconomic status). Such examination of benefits of cessation requires very large sample sizes, with careful attention to reverse causality (as disease can itself induce cessation). This project will quantify the disaggregated benefits of smoking cessation within the UK Biobank cohort, and be accompanied by similar analyses in other cohorts around the world. We will, over 24 months, investigate disease and death reductions from smoking cessation, conduct age-specific analyses of the benefits of early cessation and compare the results across countries. This study will help provide information to smokers on the benefits of cessation.