Smoking and the incidence of coronary heart disease in an Australian population.

OBJECTIVE

To estimate the impact of smoking on the incidence of coronary heart disease in Australia. Data collected for the WHO MONICA Project were used.

DESIGN

Combined data from a community-based register of all suspected coronary events and a survey of risk factor prevalence in a random sample of the same population.

SETTING AND PARTICIPANTS

All residents of the Hunter Region of New South Wales aged 35-69 years who had a first acute myocardial infarction or fatal heart attack (without a history of coronary heart disease) between 1 January 1986 and 31 December 1990.

MAIN OUTCOME MEASURES

Acute myocardial infarction or coronary death, as defined by the WHO MONICA Project.

RESULTS

Men who are current smokers are 2.9 times (95% CI, 2.7-3.1) more likely than non-smokers to have a first myocardial infarction or fatal heart attack, and for women the equivalent figure is 3.5 times (95% CI, 3.2-3.8), after adjusting for age. Current male smokers with a history of hypertension are 4.5 times more likely to have a coronary event (7.9 times in women) than are non-smokers without a history of hypertension. The age-adjusted excess rate was 566 per 100,000 per year in men and 373 per 100,000 per year in women. Smoking is a stronger predictor of coronary heart disease incidence than a history of hypertension (relative risk [RR] = 1.6 for men and 1.9 for women) or a known history of hypercholesterolaemia (RR not significantly different from 1).

CONCLUSIONS

Cigarette smoking plays a more important role in the causation of a first myocardial infarction or fatal heart attack and appears to have more influence on the incidence of coronary heart disease in Australia than hypertension.