The effects of changes in smoking habits on coronary heart disease mortality.

Coronary heart disease (CHD) mortality declined by about 20 per cent between 1965 and 1976. During the same period there were substantial decreases in the proportion of adults who smoked based on data from the National Health Interview Survey (HIS). This study examines the extent to which changes in smoking can account for the decrease in CHD mortality for men and women aged 35-64 years. By applying US smoking levels (estimated from HIS) to data from four epidemiologic studies on the relative risk of CHD death by amount smoked, we obtain estimates of the portion of the decline in CHD mortality attributable to changes in smoking. Smoking changes among women were not generally consistent with declines in CHD mortality. For men, the estimated impact of smoking on CHD mortality varied considerably depending upon which study was used to estimate the relative risk by amount smoked.