Busselton Heart Study
Background / Question:
The Busselton Heart Study was started in 1966 by Timothy Welborn and colleagues to assess the relation of CVD risk factors and their trends to CVD mortality trends and to provide a comparison with other long-term total community surveillance in America and across the world.
Population / Methods:
The study looked at serial cross-sectional 3-year surveys of the population over 21 years old in Busselton, Australia from 1966 to 1981 and then followed the cohort for an average of 20 years. There was a consistently high response rate greater than 90 per cent. The data include a social and medical history, blood pressure and mid-triceps fat-fold recording, height and weight, venipuncture, and electrocardiogram. Cox proportional hazards regression was used for calculating risk of CVD in the cohort for comparison with coefficients for the Framingham population.
The study addressed serial trends in risk factors and age differences and showed decreases over time for cholesterol and fat-fold levels, smoking rates, and systolic blood pressure . There was an increase in body mass index while diastolic pressure declined initially and then began to climb again in 1978. Most risk factor levels were greater with age. The older the group the fewer the smokers. In levels of cholesterol, diastolic blood pressure and body mass index, values were higher at every age until 60 or 70 and thereafter were lower. Of the separately observed time trends in CVD mortality rates, the authors estimated 67 percent of the decline among men and 22 per cent of that among women could be “attributed” to changes in the prevalence or the distribution shift of risk factors. Age, blood pressure, anti-hypertensive therapy, smoking, diabetes, and pre-existing CVD were risk predictors for stroke, very similar to those of Framingham. Moderate alcohol consumption was associated with less than expected risk.
Conclusions / Discussion:
This study was unique in its inclusion of data on risk factors at the beginning of a downturn in Australia’s coronary disease and stroke mortality and the systematic serial cross-sections to assess risk factor trends as explanation for the mortality decline, as well as for its measurement of risk factors in the elderly. The trends and the predictive factors among the cohort were similar to those seen in the National Heart Foundation studies in Australia’s capital cities, as well as in North American studies in Framingham, the Lipid Research Clinics Prevalence Study, and the Minnesota Heart Survey. (FB/HB)
Welborn, T.A., Cumpston, G.N., Cullen, K.J., Curnow, D.H., McCall, M.G., Stenhouse, N.S. “The Prevalence of Coronary Heart Disease and Associated Factors in an Australian Rural Community.” American Journal of Epidemiology (1969) vol. 89(5): 521-536.
Knuman, M.W., Jamrozik, K., Welborn, T.A., Bulsara, M.K., Divitini, M.L., Whittall, D.E. “Age and Secular Trends in Risk Factors for Cardiovascular Disease in Busselton.” Australian Journal of Public Health (1995) vol. 19:375-382.