Comorbidity of five chronic health conditions in elderly community residents: determinants and impact on mortality.

Background: Comorbidity is common in elderly persons. Its extent, correlates, and life-threatening impact in representative community residents are unclear.

Methods: Self-reported information of physician-diagnosed coronary artery disease (CAD), cerebrovascular disease (CVD), diabetes, and cancer was obtained annually between 1986-87 and 1992-93, and hypertension was obtained triennially from the participants of the Duke Established Populations for Epidemiologic Studies of the Elderly, a stratified multistage sample of 4,126 Black and White community residents aged 65-100, living in a five-county area of North Carolina. Date of death was obtained from death certificates identified through search of the National Death Index. Statistical procedures included descriptive statistics, logistic regression, and survival analysis.

Results: Of this sample, 57% reported hypertension, 20% diabetes, 15% CAD, 9% cancer, and 9% CVD; 29% reported none of these conditions, whereas 29% reported two or more. Demographic characteristics were not related to comorbidity with CVD or cancer. Increased education tended to be protective. The effect of age, gender, and race varied with condition. At baseline there was substantial comorbidity among hypertension, CAD, CVD, and diabetes, but not with cancer. Hypertension, CVD, and diabetes were risk factors for CAD, whereas diabetes was a risk factor for CVD. After controlling for demographic characteristics, all health conditions except hypertension were predictive of 6-year mortality, as was the presence of comorbidity.

Conclusion: We found significant comorbidity in older persons who have hypertension, CAD, CVD, or diabetes; particular risk of developing comorbidity, particularly CAD, among those with hypertension, CVD, and diabetes; and risk of CVD in those with diabetes. With the exception of hypertension, these conditions, and comorbidity per se, are life-threatening.