Abstract 3447: Prevalence of PAD Varies Significantly Depending on the Method of Calculating Ankle Brachial Index: Results from the National Health and Nutrition Examination Survey (1999–2004)

Abstract

Background: Peripheral artery disease (PAD), a marker of subclinical coronary artery disease, is associated with increased morbidity and mortality. PAD is diagnosed by calculating the ankle brachial index (ABI). There exist different methods of calculating the ABI. The effects of various methods of calculating ABI on PAD prevalence is unknown. Methods: We analyzed data from three National Health and Nutrition Examination Surveys (NHANES) between the years 1999 –2004. The prevalence of PAD using three different methods of calculating ABI was determined in 5,376 participants, age 40 years and older with no prior history of cardiovascular disease . ABI, defined as an ankle-brachial index <0.9, was determined using the NHANES method, HAP method, and LAP method (TABLE 1 ). Statistical analysis was performed using SPSS V15.0. Results: The prevalence of PAD among asymptomatic adults without CVD increased significantly during the six year time period 1999 –2004 regardless of the method used to determine ABI (TABLE 1 ). Across the 3 NHANES assessments, the ABI method used significantly affected calculated PAD prevalence (TABLE 1 ). The resulting differences in calculated PAD prevalence corresponds to approximately 2.2 million persons who would be reclassified as having or not having PAD based on type of ABI method. Conclusions: This study demonstrates that the calculated prevalence of asymptomatic PAD in a nationally representative sample of the United States population varies significantly by the ABI method. Further study is required to determine the most accurate method of performing ABI. TABLE 1: NHANES Method: ABI of right or left side =mean SBP (mm Hg) of the right or left ankle/ mean of the two brachial SBP (mm Hg). HAP Method: ABI of right or left side =higher of the right or left ankle SBP (mm Hg)/ higher of the two brachial SBP (mmHg). LAP Method: ABI of right or left side =lower of the right or left ankle SBP (mm Hg)/ higher of the two brachial SBP (mm Hg).