Kidney disease, Framingham risk scores, and cardiac and mortality outcomes.

BACKGROUND: The Framingham equations were developed to predict incident coronary heart disease. It remains unknown how the presence of chronic kidney disease affects their performance.
METHODS: Individuals without preexisting cardiovascular disease aged 45 to 74 years from the Atherosclerosis Risk in Communities and Cardiovascular Health Studies were analyzed. Using sex- and race-specific Cox models, we evaluated the 5-year risk of coronary heart disease and mortality events associated with both chronic kidney disease and Framingham risk score, the absolute risk of events caused by kidney disease, and model discrimination.
RESULTS: Among 15,717 subjects, 756 (4.8%) had kidney disease. The Framingham risk score independently predicted cardiac and mortality events in all subgroups, whereas kidney disease predicted events in all subgroups except cardiac events in white women. After adjustment for traditional risk factors, the increase in cardiac and mortality events per 1000 person-years attributable to kidney disease was 4.3 and 13.7 for white men, 16.1 and 40.5 for African American men, 1.2 and 5.8 for white women, and 13.6 and 14.2 for African American women, respectively. This represented an additional 17,000 and 12,000 cardiac events and 63,000 and 19,000 deaths per year among whites and African Americans, respectively. Mortality rates attributable to kidney disease, diabetes, and smoking were comparable. Accounting for kidney disease improved discrimination for only mortality outcomes in white men and African American women.
CONCLUSIONS: Chronic kidney disease in a community-based population is an important predictor of cardiac and mortality events, particularly in African Americans, but it does not improve discrimination of Framingham equations.