Abstract 15085: Modest Reduction in Ankle-Brachial Index Measurements and Risk of Major Adverse Limb Events Among 133,373 Veterans

Introduction: Low resting ankle-brachial index (ABI) serves as a non-invasive biomarker of poor limb outcomes. Whether modest decrements in ABI translate into higher risks of major adverse limb events (MALE) are unclear, particularly among women and minorities, because prior studies are small or lack racial diversity and incident outcomes. Methods: We analyzed data from participants in the Veterans Affairs Birth Cohort, a prospective, longitudinal cohort of veterans born between 1945-1965 with no clinical history of PAD prior to ABI testing. Participants were enrolled on or after 1/1/2000 and followed through 12/31/2016. The exposure was resting ABI and the outcome was MALE defined as limb revascularization or amputation based on VA and Medicare ICD-9/10 and CPT codes. Cox proportional hazards models assessed the association between ABI and MALE among black and white men and women. Models were adjusted for demographics and PAD risk factors ( Figure Legend ). Results: The analysis included 23,733 black men, 1,257 black women, 96,220 white men, and 2,813 white women. There were 14,431 MALE events. Risk for MALE across the ABI spectrum followed a j-shaped distribution ( Figure ). Both low and high ABIs were associated with an increased risk of MALE for black and white men and women ( Figure ). When we analyzed each sex/race group separately, as compared to a normal ABI measurement (1.11-1.20), a modestly reduced ABI (0.81-0.90) was associated with a significantly increased risk of MALE: black men HR adj , 2.17; 95% CI, 1.67-2.80; black women HR adj , 3,24; 95% CI, 1.21-8.69; white men HR adj , 3.04; 95% CI, 2.68-3.46; white women HR adj , 4.56; 95% CI, 1.73-11.99. Conclusions: In a large, diverse cohort of people free of prior PAD, a modest reduction in ABI was associated with a greater than two-fold increased risk of MALE for all sex/race groups. Further studies are needed to better understand why MALE occurs in this patient population despite only mildly reduced limb perfusion.