Abstract

SUBJECT OBJECTIVE--To test the hypotheses that the knowledge that the serum cholesterol concentration is raised (> or = 6.5 mmol/l) will lead to a reduction in the concentration after education intervention and that the knowledge that the concentration is not raised does not lead to an increase in the serum cholesterol concentration after education intervention. DESIGN--Prospective randomised trial, with investigators blind to the randomisation. SETTING--An industrial site in Manchester, England. PARTICIPANTS--A total of 495 employees of Imperial Chemical Industries, 469 of whom completed the trial. MAIN RESULT--There was a significant reduction in the serum cholesterol concentration of those whose initial concentration was > or = 6.5 mmol/l and who were given the result. This reduction was 0.28 mmol/l greater than in the control group. The reduction was similar, however, to the increase in the serum cholesterol concentration in those whose initial concentration was < 5.2 mmol/l, regardless of whether or not they had been given the result. CONCLUSION--These results support the hypotheses, although the lack of regression to the mean in the control group with high serum cholesterol suggests that this conclusion should be treated with caution.