Smoking is strongly related with all-cause mortality
Smoking was associated with all-cause mortality after 10-years of follow-up in all cohorts of the Seven Countries Study except the Japanese, apparently due to the small number of events in Japan in the early follow-up. The strength of this association was stronger in the cohorts from the US and northern Europe than in the eastern and southern European cohorts. After 25 years of follow-up, in contrast, smoking was associated with higher all-cause mortality in all 16 cohorts. For example, the 40-year follow-up data from the Zutphen Study showed that smokers had a 60% higher all-cause mortality compared to non-smokers. In the elderly men of Finland, the Netherlands, and Italy, the 10-year all-cause mortality was 67% higher in smokers than in non-smokers.
Apparent large health gain from stopping smoking
Men who stopped smoking at age 40 had 4.6 years greater life expectancy, while men who stopped smoking at age 70 had an added 2.5 years. Life expectancy at age 40 was 6.8 years shorter for cigarette smokers compared to non-smokers and 8.8 years for men who smoked more than 30 cigarettes per day. Exclusively cigar or pipe smokers had a 4.7 year lower life expectancy.