Evaluating CMR
Assessing CVD Risk: Traditional Approaches
PROCAM
- 1Key Points (1 page)
- 2The PROCAM study (2 pages)
- 3The PROCAM risk algorithm (2 pages)
- 4Key findings of the PROCAM study (3 pages)
- 5References (1 page)
Key findings of the PROCAM study
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One of the most important findings of the PROCAM study was the recognition that risk factors do not act in isolation but in conjunction with other risk factors. Similar to previous prospective studies (15), individual risk factors have a multiplicative rather than additive effect in predicting CHD events. An example of this is the interaction between total cholesterol and HDL cholesterol reported in the PROCAM study (16). After stratifying subjects into quartiles of cholesterol levels and tertiles of HDL cholesterol levels, CHD risk increased considerably (~60-fold) among men with elevated total cholesterol (>7.77 mmol/l or >300 mg/dl) and low HDL cholesterol (<0.91 mmol/l or <35 mg/dl) when compared to men with a total cholesterol below 5.18 mmol/l (200 mg/dl) and HDL cholesterol above 1.42 mmol/l (55 mg/dl) (17). This interaction between total cholesterol and HDL cholesterol was the strongest predictor of CHD among men of the PROCAM study.
The PROCAM study also highlighted the importance of HDL cholesterol to the development of CHD (18). Individuals with low HDL cholesterol levels had a roughly fourfold greater risk of CHD compared to individuals with normal HDL cholesterol levels. When stratified into tertiles of HDL cholesterol levels, the incidence of CHD among individuals in the first tertile (lowest HDL cholesterol levels) was higher than that of individuals in the top tertile (highest HDL cholesterol levels). Moreover, compared to men who remained asymptomatic, subjects with MI had lower HDL cholesterol distribution values.
In addition, the stratification of subjects for both HDL and LDL cholesterol levels revealed that individuals with low HDL cholesterol levels had an increased risk of CHD regardless of their LDL cholesterol concentration (18). However, the worst case scenario was the combination of low HDL cholesterol and elevated LDL cholesterol. This combination was clearly tied to the highest CHD risk, far beyond that of elevated LDL cholesterol or low HDL cholesterol on an individual basis. HDL cholesterol levels therefore have a much stronger influence on CHD risk in individuals with elevated global cardiovascular risk (19), supporting the notion that risk factors do not act in isolation but in synergy.
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