Short- and long-term association of serum cholesterol with mortality. The 25-year follow-up of the Finnish cohorts of the seven countries study.

The association of serum cholesterol with cause-specific and all-cause mortality was assessed in a cohort of 1,426 men aged 40-59 years who were free of clinically evident heart disease at baseline (1959). A total of 748 deaths (53 percent of the participants) occurred during the 25-year follow-up period. Men with high serum cholesterol levels at baseline had high mortality due to coronary heart disease during both the early and later parts of the follow-up period. In contrast, the association of serum cholesterol with mortality due to causes other than coronary heart disease changed during follow-up (interaction of cholesterol with follow-up period: p = 0.004). During the first 10 years of follow-up, despite their high coronary mortality, men with high cholesterol levels had lower all-cause mortality (age-adjusted relative risk = 0.71 for serum cholesterol above 5.79 mmol/liter vs. below 5.80 mmol/liter; p = 0.03) because of their low cancer mortality (relative risk = 0.55, p = 0.03) and residual mortality (relative risk = 0.49, p less than 0.01). During the last 15 years of follow-up, cholesterol at baseline was no longer associated with mortality due to causes other than coronary heart disease, and consequently, because of their high coronary mortality, men with high cholesterol levels also had higher all-cause mortality (relative risk = 1.22, p = 0.05). The results suggest that to fully analyze the association of serum cholesterol with all-cause mortality, the follow-up period should be sufficiently long--possibly more than 10 years--and the possibility of a change in the direction of the association studied should always be considered.