Mortality and cardiovascular risk across the ankle-arm index spectrum: results from the Cardiovascular Health Study.
BACKGROUND
A low ankle-arm index (AAI) is a strong predictor of mortality and cardiovascular events. A high AAI also appears to be associated with higher mortality risk in select populations. However, mortality and cardiovascular risk across the AAI spectrum have not been described in a more broadly defined population.


RESULTS
We examined total and cardiovascular mortality and cardiovascular events across the AAI spectrum among 5748 participants in the Cardiovascular Health Study (CHS). The mean age of the sample population was 73+/-6 years, and the sample included 3289 women (57%) and 883 blacks (15%). The median duration of follow-up was 11.1 (0.1 to 12) years for mortality and 9.6 (0.1 to 12.1) years for cardiovascular events. There were 2311 deaths (953 of which were cardiovascular) and 1491 cardiovascular events during follow-up. After adjustment for potential confounders, AAI measurements < or =0.60 (hazard ratio [HR] 1.82, 95% CI 1.42 to 2.32), 0.61 to 0.7 (HR 2.08, 95% CI 1.61 to 2.69), 0.71 to 0.8 (HR 1.80, 95% CI 1.44 to 2.26), 0.81 to 0.9 (HR 1.73 95% CI 1.43 to 2.11), 0.91 to 1.0 (HR 1.40, 95% CI 1.20 to 1.63), and >1.40 (HR 1.57, 95% CI 1.07 to 2.31) were associated with higher mortality risk from all causes compared with the referent group (AAI 1.11 to 1.20). The pattern was similar for cardiovascular mortality. For cardiovascular events, risk was higher at all AAI levels <1 but not for AAI levels >1.4 (HR 1.00, 95% CI 0.57 to 1.74). The association of a high AAI with mortality was stronger in men than in women and in younger than in older cohort members.


CONCLUSIONS
In a cohort of community-dwelling elders, mortality risk was higher than the referent category of 1.11 to 1.2 among participants with AAI values above the traditional cutpoint of 0.9 (ie, 0.91 to 1.0 and >1.4), and the specific association of AAI with mortality varied by age and gender.
O'Hare
Ann M
AM
Nephrology Division, Department of Medicine, VA Medical Center San Francisco, University of California, San Francisco, CA, USA. Ann.O'Hare@med.va.gov
Katz
Ronit
R
Shlipak
Michael G
MG
Cushman
Mary
M
Newman
Anne B
AB
D000368:Aged; D000842:Ankle / Q000098:blood supply; D001132:Arm / Q000098:blood supply; D001794:Blood Pressure; D015992:Body Mass Index; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D016491:Peripheral Vascular Diseases / Q000175:diagnosis* / Q000401:mortality*; D012307:Risk Factors; D012907:Smoking / Q000401:mortality
D008078:Cholesterol, LDL