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Background Dysregulation of immunologic and coagulation systems is common in elderly persons and is associated with many diseases of aging. Thrombotic events are a major cause of morbidity and mortality in the elderly population. This study assesses whether D-dimer, a marker of fibrinolytic activity, varies systematically by demographic, health, and functional measures, and derives a prediction model for factors related to D-dimer in a sample of community-dwelling elderly persons. Methods D-dimer levels were assessed in a random sample of 1,727 community-dwelling elderly persons from five rural and urban counties in North Carolina in 1992, as part of the Established Populations for the Epidemiologic Studies of the Elderly (Duke University). All subjects were 72 years or older at the time of the blood draw. In addition, all subjects were surveyed yearly by telephone or in person each year from 1986 to 1992 for a variety of health, functional, and social factors. Levels of D-dimer in 1992 were related cross-sectionally to demographics (age, race, education, income, gender, smoking), function (Nagi, Rosow-Breslau, Katz, Older Americans Resources and Services procedures instrumental activities of daily living), life satisfaction and self-rated health, self-reported diseases (heart attack, cancer, stroke, diabetes, and hypertension), and weight change from 1986 to 1992. Results D-dimer levels increased with increasing age and functional disability. Among the health variables, only high blood pressure was predictive of D-dimer level. D-dimer levels were dramatically higher in blacks. Blacks were nearly four times more likely to have an extreme value of D-dimer (>600 microg/l) than whites when high D-dimer (yes/no) was analyzed, and blacks had an average level that was nearly 40% higher than whites in analyses of the continuous version of the outcome. This racial effect was not substantively affected in multivariable analyses with demographic and socioeconomic variables controlled. Race, age, functional status, current smoking, high blood pressure, and weight loss were related to level of D-dimer, and race, age, and functional status were related to the presence of a high D-dimer level (in the top 10% of the sample). Conclusions Black, older, and functionally impaired persons had significantly higher levels of D-dimer in this sample of community-dwelling elderly persons. The findings for race were particularly striking and persisted even after controlling for smoking and other factors known to be related to thrombosis and were not mediated by social factors. This result may contribute to our understanding of the increased levels of thrombotic events found in these groups.

Background IL-6 is a multifunctional cytokine that has been shown to increase with age. Methods Plasma IL-6 was measured by ELISA in 1,727 community-dwelling elderly subjects whose blood was drawn during the third in-person survey of the Duke Established Populations for Epidemiologic Studies of the Elderly (EPESE). Demographics, functional status (disability), and disease states were determined. Correlations of these factors with IL-6 were analyzed with Spearman's Rho while differences between groups were assessed by Wilcoxon test. Results IL-6 levels were higher with age (p = .0001) even in this older population (> 70 years). There was a positive correlation between IL-6 and functional disability for each of the functional status measures (p = .0001), as well as a correlation between self-rated health and IL-6. Significantly higher median levels of IL-6 were found in subjects reporting prevalent cancer, heart attack, and high blood pressure, but not diabetes or arthritis. The association between age and functional status with high IL-6 remained when all other variables were controlled, in multivariable analysis. Conclusions This association between increased plasma IL-6 levels and functional status suggests that dysregulation of IL-6 may be related to the functional disability seen with aging, and that IL-6 may be useful as a component of an overall marker of health.