CARDIOVASCULAR RISK DETERMINATION - DISCREPANCY BETWEEN TOTAL CHOLESTEROL EVALUATION AND 2 COMPOUND LABORATORY INDEXES IN NORWAY

Objective - To compare group classification of cardiovascular risk by two compound laboratory indices with classification according to the s erum total cholesterol concentration alone. Design - Healthy employees were defined as low and high cardiovascular risk subjects according t o their total cholesterol concentration or two compound indices of blo od lipid components - the total cholesterol:high density lipoprotein ( HDL) cholesterol ratio and an atherogenic index defined as ([total cho lesterol - HDL cholesterol] [apolipoprotein B])/([HDL cholesterol]* [ apolipoprotein A-I]). Cut off values to distinguish between low and hi gh risk subjects were as follows: total cholesterol 6.5 mmol/l, HDL ch olesterol 0.9 mmol/l, apolipoprotein A = 1.8 g/l, and apolipoprotein B = 1.3 g/l. These gave total:HDL cholesterol ratio and atherogenic ind ex cut off values of 7.2 and 4.5 respectively.Setting - An occupationa l health service in a non-manufacturing company in Norway. Participant s - A total of 112 male and 117 female employees. The mean body mass i ndex values were 25.6 and 23.6 kg/m(2) and the mean ages 39.8 and 40.1 years in men and women respectively. Those with cardiovascular, diabe tic, or renal diseases were excluded. Mean outcome measures - Serum to tal cholesterol, HDL cholesterol, apolipoproteins A-I and B, lipid per oxidation, blood pressure, smoking, physical activity, and fruit, vege tables, and salt in the diet were determined. Results - The cut off va lues allocated 19%, 7%, and 40% as high risk subjects according to tot al cholesterol, total:HDL cholesterol, and the atherogenic index respe ctively. The mean age was two to four years higher in the high risk gr oups. Cardiovascular risk in siblings and no reported physical activit y were more prevalent in those high risk groups defined by the compoun d indices than by total cholesterol alone, as was a high body mass ind ex and a measure of lipid peroxidation. Grouping according to total ch olesterol failed to allocate heavy smokers mainly to the high risk gro up. Diet variables did not demarcate clearly between indices. Conclusi ons - There is considerable variability in classification into high an d low risk subjects when using the total cholesterol concentration alo ne compared with compound risk indices. Smoking was more prevalent in the high risk groups defined by the compound indices than by total cho lesterol. These findings call for caution when total cholesterol is us ed to estimate cardiovascular risk in epidemiological studies, and eve n more so at individual counselling in occupational or primary health care settings.