Adjustment for eight established risk factors reduced the geographic variation in true age-adjusted CHD incidence among British towns by 50%.
Cohort (n=7,735)
Yes
To what extent do established risk factors explain the geographic variation in the incidence of major coronary heart disease among men in Great Britain?
Established cardiovascular risk factors account for approximately half of the geographic variation (including the north-south gradient) in coronary heart disease incidence among men in Great Britain.
OBJECTIVE: To determine the extent to which geographic variation in the incidence of major coronary heart disease (CHD) in Great Britain may be explained by established risk factors. DESIGN: Prospective study. SETTING: 24 British towns with widely differing CHD mortality. SUBJECTS: 7735 men followed up from screening in 1978-80 for 15 years. MAIN OUTCOME MEASURES: Percentage of variance between the towns in major CHD incidence that can be explained by individual characteristics of men in the towns. RESULTS: Age standardised incidence rates over a 15 year period varied from 0.52% per annum in Maidstone to 1.07% per annum in Dewsbury and tended to follow the known pattern of higher rates in Scottish and northern English towns and lower rates in southern English towns ("north-south gradient"). Higher town incidence rates were related to prevalence of current cigarette smoking, low physical activity, and low alcohol consumption, and to mean body mass index, mean systolic blood pressure, low mean height, and prevalence of manual social class, but not to mean serum total cholesterol. The 95% range for true age adjusted CHD incidence (over 15 years) was estimated as 0.58-1.03% per annum among British towns. After adjustment for baseline smoking status, physical activity, body mass index, alcohol consumption, systolic blood pressure, serum total cholesterol, occupational social class, and height, this variation was reduced by 50%. A model based on these eight variables accounted for the major part of the north-south gradient. CONCLUSIONS: Much of the variation in CHD incidence among British towns was accounted for by established risk variables. The remaining unexplained variation may be related to measurement error in the established risk variables, to environmental factors such as climate, or to the combined effect of a wide range of minor risk factors.
Richard Morris (Sat,) conducted a cohort in coronary heart disease (n=7,735). Established risk factors (smoking, physical activity, BMI, alcohol, blood pressure, cholesterol, social class, height) was evaluated on Percentage of variance between the towns in major CHD incidence that can be explained by individual characteristics. Adjustment for eight established risk factors reduced the geographic variation in true age-adjusted CHD incidence among British towns by 50%.