Cigarette consumption and deaths from coronary heart-disease
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Cigarette smoking significantly increases coronary heart-disease (C.H.D.) risk. Reducing daily cigarette consumption, especially for heavy smokers, can substantially lower C.H.D. mortality risk.
Area of Science:
- Cardiology
- Epidemiology
- Public Health
Background:
- Cigarette smoking is a known risk factor for coronary heart-disease (C.H.D.).
- Previous studies indicated a dose-response relationship between smoking and non-fatal myocardial infarction.
Purpose of the Study:
- To investigate the association between cigarette consumption levels and mortality from C.H.D.
- To quantify the risk ratio for C.H.D. deaths among smokers compared to non-smokers.
Main Methods:
- A matched-pair case/control study design was employed.
- Data on cigarette consumption were collected and analyzed to determine risk ratios (R.R.).
- Statistical adjustments were made for potential confounding variables.
Main Results:
- An overall R.R. of 1.9 for C.H.D. deaths was observed in current smokers versus non-smokers.
- A clear dose-response relationship was found: R.R. was 1.2 (1-19 cigarettes/day), 2.3 (21-40 cigarettes/day), and 4.0 (41+ cigarettes/day).
- Adjusted analyses confirmed these dose-dependent risk increases.
Conclusions:
- Reducing smoking intensity can significantly decrease C.H.D. mortality risk.
- Heavy smokers could halve their risk by reducing consumption; moderate smokers benefit from cutting down below 20 cigarettes daily.
Abstract:
There is a positive association between cigarette smoking and coronary heart-disease (C.H.D.). In non-fatal myocardial infarction a dose-response relation persists even after the effects of additional variables have been controlled for. The relation between cigarette consumption and deaths from C.H.D. was investigated in a matched-pair case/control study. The overall simple matched-pair risk ratio (R.R.) between current smokers and non-smokers was 1.9 (95% confidence limits 1.5-2.4). For smokers of fewer than 20 cigarettes per day, the R.R. was 1.2; at a level of 21-40 cigarettes per day, the R.R. was 2.3; and for smokers of 41+ cigarettes per day, the R.R. was 4.0. A similar relation was found after adjustment for additional variables. These results suggest that the heaviest smokers could halve their risk of death from C.H.D. by reducing their tobacco consumption to an intermediate level; and that benefit of a similar order would be experienced by smokers of 21-40 cigarettes per day who cut down to less than one pack (20 cigarettes) daily.