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Coronary heart disease mortality in the Western Collaborative Group Study. Follow-up experience of 22 years
1School of Public Health, University of California, Berkeley 94720.
Insights
Traditional coronary heart disease risk factors like blood pressure, cholesterol, smoking, and age predict mortality. Type A/B behavior showed no significant long-term association with coronary heart disease death in this cohort study.
Area of Science:
- Cardiovascular epidemiology
- Behavioral medicine
Background:
- The Western Collaborative Group Study initiated in 1960-1961, enrolled 3,154 healthy middle-aged men to investigate coronary heart disease (CHD).
- A 22-year mortality follow-up confirmed 214 deaths from CHD within the cohort.
Purpose of the Study:
- To assess the predictive value of baseline variables including Type A/B behavior, systolic blood pressure, serum cholesterol, smoking status, and age on 22-year CHD mortality.
- To re-evaluate the role of Type A/B behavior as a CHD risk factor.
Main Methods:
- Utilized a proportional hazards regression model to analyze risk factors.
- Examined associations over four successive time intervals post-baseline.
Main Results:
- Systolic blood pressure, serum cholesterol, smoking status, and age were highly significant predictors of CHD mortality (p < 0.001).
- Type A/B behavior demonstrated no significant association with 22-year CHD mortality (SRH = 0.98, 95% CI = 0.85-1.12).
- While traditional risk factors showed consistent associations, Type A/B behavior exhibited inconsistent associations, including a significant negative association in the second interval.
Conclusions:
- Traditional risk factors (blood pressure, cholesterol, age, smoking) are confirmed as critical predictors of coronary heart disease mortality.
- The study raises significant questions regarding the long-term importance of Type A/B behavior as a predictor of coronary heart disease mortality.
Abstract:
In 1960-1961, 3,154 healthy, middle-aged men were entered into the Western Collaborative Group Study, a long-term study of coronary heart disease. A 22-year mortality follow-up of this cohort in 1982-1983 accounted for almost 99% of the cohort, and determined that 214 of the men had died of coronary heart disease. The risk of coronary heart disease mortality was studied for several variables measured at baseline, i.e., Type A/B behavior, systolic blood pressure, serum cholesterol level, cigarette smoking status, and age. Using a proportional hazards regression model, systolic blood pressure, serum cholesterol level, cigarette smoking status, and age were highly significant predictors (p less than 0.001) of 22-year coronary heart disease mortality. Type A/B behavior showed no association with 22-year coronary heart disease mortality (standardized relative hazard (SRH) = 0.98, 95% confidence interval (CI) = 0.85-1.12). Systolic blood pressure, serum cholesterol, and age showed relatively consistent positive associations with coronary heart disease mortality over four successive time intervals after the baseline examination. Cigarette smoking showed a significant positive association in the first and second intervals and a nonsignificant positive association in the third and fourth intervals. Type A/B behavior was positively but not significantly associated with coronary heart disease in the first and third intervals, significantly negatively associated (SRH = 0.70, 95% CI = 0.53-0.93) in the second interval and not associated in the fourth interval. The results confirm the importance of the traditional coronary heart disease risk factors, and raise a substantial question about the importance of Type A/B behavior as a risk factor for coronary heart disease mortality.