Mortality in Twins in Relation to Smoking Habits and Alcohol Problems

Results are presented from an 11-year study on 9,000 pairs. On a nonpair basis, a significant hypermortality was related to smoking in men and women. Among 706 male dizygotic smoking-discordant pairs born 1901 to 1925, 55 deaths or “first deaths” occurred in a high smoking group, against 31 in a low smoking group. Among 246 corresponding monozygotic male pairs, the numbers were 18 vs 18. For women, the numbers were 42 vs 31 among 781 dizygotic pairs, and 14 vs 13 among 326 monozygotic pairs. The hypermortality was mainly due to coronary heart disease, lung cancer, suicides, and accidents. Nonsmokers were registered at 10% in a nationwide “alcohol registry” as against 30% for high smokers. The mortality among the registered subjects was significantly higher than among the nonregistered, regardless of smoking. Data imply that part of the hypermortality among smokers is not due to smoking per se, but to factors associated with smoking.