Changes in serum cholesterol level and mortality: a 30-year follow-up. The Finnish cohorts of the seven countries study.

The association of past changes in serum cholesterol level with cause-specific mortality between 1974 and 1989 was examined in a cohort of 784 Finnish men aged 55-74 years who were free of symptomatic coronary heart disease in 1974. Changes in serum cholesterol level were computed based on measurements made in 1959, 1964, 1969, and 1974. Of the 405 deaths, 202 were due to cardiovascular diseases and 107 due to cancer. Men with a decline in serum cholesterol level between 1959 and 1974 also experienced greater than average declines in body mass index and tended to be more often current smokers in 1974. Among 339 men aged 65-74 years in 1974, men in the lowest tertile of serum cholesterol change, i.e., with greatest declines, had increased cardiovascular (hazard ratio, 1.58; 95% confidence interval 1.00-2.50) and all-cause (hazard ratio, 1.46; 95% confidence interval 1.06-2.02) mortality compared with men in the middle tertile of change, i.e., with least change, in multivariate analysis. Among 445 men aged 55-64 years in 1974, there was a significant U-shaped association between change in serum cholesterol level and coronary and all-cause mortality risk. The authors suggest that both the decline in serum cholesterol level and the associated high mortality may be caused by a third factor, such as increased prevalence of chronic diseases or other changes associated with aging. This would help to explain why several studies have not found an association of serum cholesterol with coronary risk among the elderly.