Atherosclerosis risk factors: variation in healthy hospital workers and members of local communities asymptomatic for vascular disease. Implications for normal controls.

The major risk factors for atherosclerosis were measured in 100 middle-aged members of the local community aged between 40 and 66 attending hospital for minor operations, hernia repair, varicose veins or endoscopy, and their healthy accompanying spouses. Levels in this group were compared with those measured in 75 age- and sex-matched hospital workers. Ten of the 12 risk factors measured were more unfavourable in the local population (P = 0.039). Levels of total cholesterol (P = 0.0013), low-density lipoprotein (LDL) cholesterol (P = 0.0002) and body mass index (P = 0.0074) were higher in members of the local community. There was no difference in levels of triglycerides, high-density lipoprotein cholesterol, von Willebrand factor (vWf, an index of damage to the endothelial cell), fibrinogen, glucose, systolic and diastolic blood pressure, waist-to-hip ratio or the proportion of smokers. We also found systolic blood pressure (P = 0.014) and vWf (P = 0.021) to be higher, while high-density lipoprotein (P = 0.022) was lower in the 35 smokers, but we could not identify any factor that correlated with age. However, systolic (P = 0.028) and diastolic (P = 0.0072) blood pressures, triglycerides (P = 0.029) and waist-to-hip ratio (P < 0.0001) were all lower, while high-density lipoprotein was higher (P < 0.0001) in the 80 women compared to the men. We conclude that precise definition of the identity of the control group is necessary in studies of risk factors for atherosclerosis, or in frank disease, if mis-interpretation is to be avoided.