Canadian Medical Association Risk Calculation

Method of Risk Assessment

The complete description of the Canadian risk assessment process is published in an appendix to the Canadian Medical Association Journal Vol 168, p921 (2003). They decided to use the same risk factor evaluation process that was presented in the U.S. Third Report of the National Cholesterol Education Program Expert Panel on Detection,Evaluation,and Treatment of High Blood Cholesterol in Adults. If you read this paper, you will need to convert their cholesterol units of mmol/L to mg/dL by multiplying the mmol/L numbers by 38.7. (For triglycerides, the factor is 88.5).

The main difference between the two approaches lies in their goal - the Canadian recommendations for target goals are expressed by the ratio of HDL to total cholesterol, in addition to lowering the LDL level. Several studies, (e.g., in Athreosclerosis, vol 137, Supplement S1, 1998) indicate that this discriminates better between high risk and low risk patients, compared to using LDL values alone. This is depicted in the figure, that shows the risk rising rapidly as the ratio increases above a value of 5.

Risk categories and target lipid levels

	Target level
Risk category	LDL-C level (mg/dL)	Total cholesterol/ HDL-C ratio
High (10-year risk of coronary artery disease > 20%, or history of diabetes mellitus† or any atherosclerotic disease)	< 97 and	< 4
Moderate (10-year risk 11%-19%)	< 135 and	< 5
Low‡ (10-year risk d 10%)	< 174 and	< 6

Note: LDL-C = low-density lipoprotein cholesterol.
†Includes patients with chronic kidney disease and those undergoing long-term dialysis.
‡In the "very low" risk stratum, treatment may be deferred if the 10-year estimate of cardiovascular disease is < 5% and the LDL-C level is < 193 mg/dL.

These risk levels are used to determine the treatment and doses of medication, if appropriate.


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