Objective: to study the impact of serum cholesterol concentrations on the total risk of mortality in older people. Design: retrospective cohort study with a follow-up of 8-10 years. Subjects: a total of 989 subjects (367 men and 622 women) aged 65 and over, living in the Marshfield Epidemiologic Study Area at the time of their first complete serum lipid assessment. Methods: we calculated sex-specific mean levels of serum total cholesterol, low-density lipoprotein, high-density lipoprotein and

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... iglycerides, and the ratio of total cholesterol to high-density lipoprotein, for subjects who died of all causes and for those who survived to the end of follow-up, with adjustment for relevant covariates. We obtained estimates of the risk factor-adjusted sex-specific relative risk for all-cause mortality with approximate quartiles of serum cholesterol concentrations by proportional hazards regression models. We also evaluated the possible combined effects of age, sex and cholesterol on all-cause mortality. Results: a high level of high-density lipoprotein was significantly associated with a low total risk of mortality in older men. Conversely, an elevated ratio of total cholesterol to high-density lipoprotein was directly related to an increased total risk of mortality in older men. Age and high-density lipoprotein level had a significant synergistic effect on all-cause mortality for the elderly men. We found little or no association in women between all-cause mortality and any of the lipid measures studied. Conclusions: an increased ratio of total cholesterol to high-density lipoprotein appears to be associated with an increase in risk for all-cause mortality in men aged 65 and over, while an elevated level of high-density lipoprotein, considered alone, seems to be protective against mortality from all causes in men aged 65-74 years, but this effect diminishes over the age of 75.