Borderline peripheral arterial disease

Prevalence of and Risk Factors for Peripheral Artery Disease in Rural South Africa: A Cross-Sectional Analysis of the HAALSI Cohort

BACKGROUND

The burden of peripheral artery disease (PAD) is increasing in low- and middle-income countries. Existing literature from sub-Saharan Africa is limited and lacks population-representative estimates. We estimated the burden and risk factor profile of PAD for a rural South African population.

METHODS AND RESULTS

We used data from 1883 participants from a rural, low-income cohort of South African adults aged 40 to 69 years with available ankle-brachial index measurements. We defined clinical PAD as ankle-brachial index ≤0.90 or >1.40, and borderline PAD as ankle-brachial index >0.90 and ≤1.00. We compared the distribution of sociodemographic variables, biomarkers, and comorbidities across PAD classifications. To identify associated factors, we calculated unadjusted and age-sex-adjusted prevalence ratios (PRs) with log-binomial models. Overall, 6.6% (95% CI, 5.6-7.7) of the sample met the diagnostic criteria for clinical PAD, while 44.7% (95% CI, 42.4-47.0) met the diagnostic criteria for borderline PAD. Age (PR: 1.9 [95% CI, 1.2-3.1] for ages 50-59 years compared with 40-49 years; PR: 2.5 [95% CI, 1.5-4.0] for ages 60-69 years compared with 40-49 years); diagnosed hypertension (PR: 1.53 [95% CI, 1.08-2.17]); and C-reactive protein (PR: 1.08 [95% CI, 1.03-1.12]) were associated with increased prevalence of clinical PAD. All other examined factors were not significantly associated with clinical PAD.

CONCLUSIONS

We found high PAD prevalence for younger age groups compared with previous research and a lack of statistical evidence for the influence of traditional risk factors for this rural, low-income population. Future research should focus on identifying the underlying risk factors for PAD in this setting. South African policymakers and clinicians should consider expanded screening for early PAD detection in rural areas.

Peripheral Artery Disease and Subsequent Risk of Infectious Disease in Older Individuals: The ARIC Study

OBJECTIVE

To quantify the association of peripheral artery disease (PAD) with infection risk because PAD has been understudied despite recognition of atherosclerotic cardiovascular disease as a risk factor for infection.

METHODS

Among 5082 participants of the Atherosclerosis Risk in Communities study (aged 71 to 90 years during 2011-2013), we assessed the association of PAD status, based on clinical history and ankle-brachial index (ABI), with infection-related hospitalization (through December 2019) using multivariable Cox regression. We also cross-classified participants by PAD and coronary heart disease (CHD)/stroke status at baseline, with implications for polyvascular disease.

RESULTS

During the median follow-up of 6.5 years, there were 1677 infection-related hospitalizations. Peripheral artery disease (clinical history or ABI ≤0.90) was independently associated with the risk of overall infection (adjusted hazard ratio [HR], 1.66 [95% CI, 1.42 to 1.94] vs ABI of 1.11 to 1.20), as was borderline low ABI of 0.91 to 1.00 (adjusted HR, 1.75 [95% CI, 1.47 to 2.07]). Results were consistent across major types of infection (ie, cellulitis, bloodstream infection, pneumonia, and urinary tract infection). For overall infection, PAD plus CHD/stroke had the highest HR of hospitalized infection (1.9), and PAD alone and CHD/stroke alone showed similar HRs of 1.6. For subtypes of infection, PAD alone had the highest HR of approximately 2 for bloodstream infection; PAD alone and PAD plus CHD/stroke had a similar risk of urinary tract infection with HR of approximately 1.7.

CONCLUSION

Peripheral artery disease and borderline low ABI were robustly associated with infection-related hospitalization of older adults. The contribution of PAD to infection risk was comparable to that of CHD/stroke, warranting clinical attention to PAD for the prevention of infectious diseases.

The Cardiovascular-Mortality-Based Estimate for Normal Range of the Ankle-Brachial Index (ABI)

Background: The ankle−brachial index (ABI) is a first-line examination in cardiovascular risk evaluation. Since cut-off values for normal ABI vary, the aim of the present study was to identify the cardiovascular-mortality-based estimate for the normal range of the ABI. After determining the reference range for the ABI, the corresponding toe−brachial index (TBI) and toe pressure for normal ABI were analyzed. Methods: All consecutive non-invasive pressure measurements in the vascular laboratory of a large university hospital 2011−2013 inclusive were collected and combined with patient characteristics and official dates and causes of death. Patients with an ABI range of 0.8−1.4 on both lower limbs were included in this study. Results: From 2751 patients, 868 had bilateral ABI values within the inclusion. Both ABI category ranges 0.80−0.89 and 0.90−0.99 had poorer survival compared to ABI categories 1.00−1.29 (p < 0.05). The 1-, 3-, and 5-year cardiovascular-death-free survival for respective ABI categories 0.80−0.99 vs. 1.00−1.29 were 90% vs. 96%, 84% vs. 92%, and 60% vs. 87%. The 1-, 3-, and 5-year overall survival for ABI categories 0.80−0.99 vs. 1.00−1.29 were 85% vs. 92%, 75% vs. 83%, and 42% vs. 74%. Conclusions: Borderline ABI (0.90−0.99) associates with higher overall and cardiovascular mortality compared to ABI values 1.00−1.29.

Quantification of serum C-mannosyl tryptophan by novel assay to evaluate renal function and vascular complications in patients with type 2 diabetes

C-Mannosyl tryptophan (CMW) is a unique glycosylated amino acid, and a candidate novel biomarker of renal function. In type 2 diabetes (T2D), a combination of metabolites including CMW has recently been the focus of novel biomarkers for the evaluation of renal function and prediction of its decline. However, previous quantification methods for serum CMW have several limitations. We recently established a novel assay for quantifying serum CMW. Serum CMW from 99 Japanese patients with T2D was quantified by this assay using hydrophilic interaction liquid chromatography. The serum CMW levels were cross-sectionally characterized in relation to clinical features, including renal function and vascular complications. Serum CMW level was more strongly correlated with serum creatinine and cystatin C levels and with eGFR than with albumin urea level. The ROC curve to detect eGFR < 60 ml/min/1.73 m2 revealed that the cutoff serum CMW level was 337.5 nM (AUC 0.883). Serum CMW levels were higher in patients with a history of macroangiopathy than in those without history. They correlated with ankle-brachial pressure index, whereas cystatin C did not. Serum CMW levels quantified by the novel assay could be useful in evaluation of glomerular filtration of renal function and peripheral arterial disease in T2D.

Lower Extremity Peripheral Artery Disease and Quality of Life Among Older Individuals in the Community

Background

Evidence regarding the association of lower extremity peripheral arterial disease with quality of life (QOL) is mainly from selected clinical populations or relatively small clinical cohorts. Thus, we investigated this association in community‐derived populations.

Methods and Results

Using data of 5115 participants aged 66 to 90 years from visit 5 (2011‐2013) of the Atherosclerosis Risk in Communities Study, we quantified the associations of ankle‐brachial index (ABI) with several QOL parameters, including 12‐item Short‐Form Health Survey (SF‐12), after accounting for potential confounders using linear and logistic regression models. Peripheral arterial disease defined by an ABI <0.90 (n=402), was independently associated with a low SF‐12 Physical Component Summary score (−3.26 [95% CI −5.60 to −0.92]), compared to the ABI reference 1.10 to 1.19 (n=1900) but not with the Mental Component Summary score (−0.07 [−2.21 to 2.06]). A low ABI was significantly associated with poorer status of all SF‐12 physical domains (physical functioning, role‐physical, bodily pain, and general health) but only vitality out of 4 mental domains. Similarly, low ABI values were more consistently associated with other physically related QOL parameters (leisure‐time exercise/activity/walking) than mentally related parameters (significant depressive symptoms and hopeless feeling). Lower physical QOL was observed even in individuals with borderline low ABI (0.90 to 0.99; n=426).

Conclusions

Low ABI (even borderline) was independently associated with poor QOL, especially for physical components, in community‐dwelling older adults. QOL is a critical element for older adults, and thus, further studies are warranted to assess whether peripheral arterial disease‐specific management can improve QOL in older populations.

Exercise training and peripheral arterial disease

Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.