Dataset Information

Ethnic differences in ankle brachial index are present in middle-aged individuals without peripheral arterial disease.

ABSTRACT:

Introduction

To better understand the basis for previously reported ethnic differences in ankle brachial index (ABI), we investigated whether these differences were present in individuals without known peripheral arterial disease (PAD).

Methods

We used data from National Health and Nutrition Examination surveys (NHANES 1999-2004) to determine whether ethnic differences were present in respondents without PAD (1 ? ABI ? 1.3). We assessed whether ethnicity was an independent predictor of ABI and ankle systolic blood pressure (SBP) in linear regression models that adjusted for conventional and novel cardiovascular risk factors. To minimize effects of atherosclerosis on ABI, we studied adults aged ? 60 years, and also repeated our analyses in a subset aged ? 50 years that did not have risk factors for PAD.

Results

3348 participants aged ? 60 years were included in the study. Mean ABI was 1.11 in non-Hispanic Blacks (NHB) and 1.13 in non-Hispanic Whites (NHW) (P < 0.0001). In multivariable linear regression analysis that adjusted for age, gender, ethnicity, smoking, height, diabetes, brachial SBP, dyslipidemia, diabetes, renal function, concurrent cardiovascular disease, and plasma levels of homocysteine, fibrinogen and C-reactive protein, NHB had lower ABI than NHW (? = -0.03 ± 0.004, P < 0.00001). Although, NHBs had higher ankle SBP than NHWs (by 5.4 mm Hg), NHBs had a lower mean ankle SBP (? = -3.663 mm Hg ± 0.500, P < 0.0001) after adjusting for clinical covariates, including brachial SBP, in multivariable analysis.

Conclusion

Ethnic differences in ABI are present in middle-aged adults at low risk for peripheral atherosclerosis.

SUBMITTER: Singh S

PROVIDER: S-EPMC3174274 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Publications

Ethnic differences in ankle brachial index are present in middle-aged individuals without peripheral arterial disease.

Singh Siddharth S Bailey Kent R KR Kullo Iftikhar J IJ

International journal of cardiology 20110608 3

<h4>Introduction</h4>To better understand the basis for previously reported ethnic differences in ankle brachial index (ABI), we investigated whether these differences were present in individuals without known peripheral arterial disease (PAD).<h4>Methods</h4>We used data from National Health and Nutrition Examination surveys (NHANES 1999-2004) to determine whether ethnic differences were present in respondents without PAD (1 ≤ ABI ≤ 1.3). We assessed whether ethnicity was an independent predict ...[more]

PMID: 21652099

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Project description:BackgroundNon-invasive clinic-based tools for assessing PAD are not without limitations. Therefore, costly tests like Doppler study, CT angiography and MR angiography are often required to make a diagnosis. Ankle brachial index (ABI), commonly used for assessment of PAD, has high false positivity rates in sclerosed, calcified arteries which render them non-compressible. Toe brachial index (TBI) can be an alternative, as digital arteries are relatively unaffected by these changes.AimTo compare the reliability of ABI and TBI in diagnosing PAD in type 2 diabetes using CT angiography (CTA) as the reference.Methods175 adults with T2D were selected. ABI &TBI were measured with an automated vascular Doppler XT 6 ports bilaterally for all subjects. For any subject, the limb with lower ABI and TBI was included for analysis. ABI < 0.9 & TBI < 0.6 were taken as evidence of PAD. CTA showing > 50% narrowing was taken as evidence of PAD.Results24% of our study subjects had CTA confirmed PAD. ABI has low sensitivity of 35.29% (95% CI 0.21-0.52) compared to TBI being 82.35% (95% CI 0.66-0.92). The specificity however was similar. ABI < 0.9 was able to detect CTA confirmed PAD, but ABI > 0.9, including the so-called normal ABI (0.9-1.3) was unable to detect PAD. ROC showed ABI at 1.005 has sensitivity 64.71% (95% CI 0.48- 0.79) and specificity 61.7% (95% CI 0.53-0.69) and TBI at 0.6 has sensitivity 82.35% (95% CI 0.66-0.92) & specificity 92% (95% CI 0.87-0.96). Utilizing Cohen's Kappa, the reliability of ABI with respect to CTA showed fair agreement (K = 0.225, p = 0.001), whereas the reliability of TBI with respect to CTA showed substantial agreement (K = 0.759, p < 0.0001).ConclusionABI < 0.9 detects PAD reliably, but presence of PAD in patients with ABI > 9.0 including the normal of ABI (0.9-1.3) can be confirmed with TBI, which correlated strongly with CTA. TBI is also non-inferior for PAD detection, when ABI < 0.9. TBI and not ABI can be utilized for initial assessment of PAD in subjects with T2D.

Project description:Pseudoxanthoma elasticum (PXE) is an inherited metabolic disease characterized by elastic fiber fragmentation and calcification in the cutaneous, ophthalmologic, and vascular tissues. Cardiovascular manifestations such as peripheral arterial disease (PAD) are frequent in PXE. Because of the changes in the elastic properties and medial calcification of the arterial wall in PXE, the impact of the arterial remodeling on the ankle brachial index (ABI), a well-established diagnostic method for the detection and follow-up of PAD, remains to be determined in this disease.This was a cross-sectional, comparative, open study, which took place at the PXE Consultation Center, University Hospital of Angers. The subjects were 53 patients (mean age, 49 ± 14 years; 35 females) with PXE clinically proven on the basis of established criteria (skin changes, angioid streaks, and skin biopsy). The ABI at rest, symptoms of intermittent claudication (IC), carotid intima-media thickness (IMT), carotid-femoral pulse wave velocity (c-f PWV), compliance (CC), and ? stiffness index were measured in a single-center cohort.Forty-five percent of the PXE patients had an ABI ?0.90, but only one patient had an ABI >1.40. IC was found in 23% of the patients with an ABI ?0.90. There were no significant differences between the patients with a low and normal ABI in terms of IMT (P = .566) or ? stiffness index (P = .194), but differences were significant for c-f PWV (P = .010) and CC (P = .011). Adjusted multivariate linear regression for the Framingham-Laurier score showed that patients with a low ABI had less compliant carotid arteries (B = 0.318, P = .039).PAD detected by a low ABI is very frequent in PXE, although with limited prevalence of symptomatic claudication. Unexpectedly, ABI was low in such calcifying PAD and associated with lower CC, independently of atherosclerosis risk factors. These findings demonstrate that PXE represents a unique monogenic model of PAD in which the specific arterial wall remodeling could change the diagnostic value of the ABI to detect PAD.

Project description:BackgroundAtherosclerotic peripheral arterial disease (PAD) affects 8-10 million people in the United States and is associated with a marked impairment in quality of life and an increased risk of cardiovascular events. Noninvasive assessment of PAD is performed by measuring the ankle-brachial index (ABI). Complex traits, such as ABI, are influenced by a large array of genetic and environmental factors and their interactions. We attempted to characterize the genetic architecture of ABI by examining the main and interactive effects of individual single nucleotide polymorphisms (SNPs) and conventional risk factors.MethodsWe applied linear regression analysis to investigate the association of 435 SNPs in 112 positional and biological candidate genes with ABI and related physiological and biochemical traits in 1046 non-Hispanic white, hypertensive participants from the Genetic Epidemiology Network of Arteriopathy (GENOA) study. The main effects of each SNP, as well as SNP-covariate and SNP-SNP interactions, were assessed to investigate how they contribute to the inter-individual variation in ABI. Multivariable linear regression models were then used to assess the joint contributions of the top SNP associations and interactions to ABI after adjustment for covariates. We reduced the chance of false positives by 1) correcting for multiple testing using the false discovery rate, 2) internal replication, and 3) four-fold cross-validation.ResultsWhen the results from these three procedures were combined, only two SNP main effects in NOS3, three SNP-covariate interactions (ADRB2 Gly 16 - lipoprotein(a) and SLC4A5 - diabetes interactions), and 25 SNP-SNP interactions (involving SNPs from 29 different genes) were significant, replicated, and cross-validated. Combining the top SNPs, risk factors, and their interactions into a model explained nearly 18% of variation in ABI in the sample. SNPs in six genes (ADD2, ATP6V1B1, PRKAR2B, SLC17A2, SLC22A3, and TGFB3) were also influencing triglycerides, C-reactive protein, homocysteine, and lipoprotein(a) levels.ConclusionWe found that candidate gene SNP main effects, SNP-covariate and SNP-SNP interactions contribute to the inter-individual variation in ABI, a marker of PAD. Our findings underscore the importance of conducting systematic investigations that consider context-dependent frameworks for developing a deeper understanding of the multidimensional genetic and environmental factors that contribute to complex diseases.

Dataset Information

Ethnic differences in ankle brachial index are present in middle-aged individuals without peripheral arterial disease.

Introduction

Methods

Results

Conclusion

Publications

Ethnic differences in ankle brachial index are present in middle-aged individuals without peripheral arterial disease.

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