Obesity, weight change, and functional decline in peripheral arterial disease

Study Design, Rationale, and Methodology for Promote Weight Loss in Patients With Peripheral Artery Disease Who Also Have Obesity: The PROVE Trial

Background Overweight and obesity are associated with adverse functional outcomes in people with peripheral artery disease (PAD). The effects of weight loss in people with overweight/obesity and PAD are unknown. Methods The PROVE (Promote Weight Loss in Obese PAD Patients to Prevent Mobility Loss) Trial is a multicentered randomized clinical trial with the primary aim of testing whether a behavioral intervention designed to help participants with PAD lose weight and walk for exercise improves 6-minute walk distance at 12-month follow-up, compared with walking exercise alone. A total of 212 participants with PAD and body mass index ≥25 kg/m2 will be randomized. Interventions are delivered using a Group Mediated Cognitive Behavioral intervention model, a smartphone application, and individual telephone coaching. The primary outcome is 12-month change in 6-minute walk distance. Secondary outcomes include total minutes of walking exercise/wk at 12-month follow-up and 12-month change in accelerometer-measured physical activity, the Walking Impairment Questionnaire distance score, and the Patient-Reported Outcomes Measurement Information System mobility questionnaire. Tertiary outcomes include 12-month changes in perceived exertional effort at the end of the 6-minute walk, diet quality, and the Short Physical Performance Battery. Exploratory outcomes include changes in gastrocnemius muscle biopsy measures of mitochondrial cytochrome C oxidase activity, mitochondrial biogenesis, capillary density, and inflammatory markers. Conclusions The PROVE randomized clinical trial will evaluate the effects of exercise with an intervention of coaching and a smartphone application designed to achieve weight loss, compared with exercise alone, on walking performance in people with PAD and overweight/obesity. Results will inform optimal treatment for the growing number of patients with PAD who have overweight/obesity. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04228978.

Obesity and Peripheral Artery Disease: Current Evidence and Controversies

PURPOSE OF REVIEW

Obesity is a significant public health problem and a major risk factor for the development and progression of atherosclerosis and its cardiovascular manifestations. Lower extremity peripheral artery disease (PAD) affects 3%-10% of the Western population and, if left untreated, can lead to devastating outcomes with both an increased risk of morbidity and mortality. Interestingly, the association between obesity and PAD remains debatable. Whereas it is well known that PAD and obesity frequently overlap in the same patients, many studies have demonstrated a negative association between obesity and PAD and a protective effect of obesity on disease development and progression, a phenomenon described as the "obesity paradox." Possible mechanisms for this paradox may include genetic background, as assessed by mendelian randomization studies, adipose tissue dysfunction, and body fat distribution rather than adiposity, while other factors, such as sex, ethnicity, sarcopenia in the elderly population, or aggressive treatment of co-existing metabolic conditions in individuals with obesity compared to those with normal weight, could have some impact as well.

RECENT RINDINGS

Few reviews and meta-analyses examining systematically the relationship between obesity and PAD exist. The impact of PAD development due to the presence of obesity remains largely controversial. However, the most current evidence, backed by a recent meta-analysis, suggests a potential protective role of a higher body mass index on PAD-related complications and mortality. In this review, we discuss the association between obesity and PAD development, progression, and management, and the potential pathophysiologic mechanisms linking the two diseases.

Objective assessment of functional capacity in patients with peripheral artery disease: a narrative review

INTRODUCTION

Peripheral artery disease (PAD) patients with claudication symptoms exhibit impaired functional capacity, which has been associated with disease severity, worse quality of life and higher risk of cardiovascular events. Different tests have been used to assess functional capacity in PAD patients. Therefore, understanding the characteristics, strengths and limitations of these tests are important to support the choice of tests to be used in clinical practice.

AREAS COVERED

This review summarizes the main methods to assess functional capacity in PAD patients, discussing their psychometric properties, applications, and limitations.

EXPERT OPINION

Robust evidence supports the use of treadmill and six-minute walk tests in PAD patients, as their results are associated with clinically meaningful outcomes, adequate psychometric properties and are sensitive to effects of interventions. On the other hand, other functional tests (Shuttle-walk test, outdoor walking capacity test, timed-up and go, four-meter walk test, heel-rise test, short physical performance battery and modified physical performance battery) are related to activities of daily living and do not require sophisticated equipment and can be easily used in clinical practice. However, these other tests still need evidence regarding their clinical relevance, reliability, and ability to detect long-term intervention changes, providing further investigation directions.

The Efficacy of HGF/VEGF Gene Therapy for Limb Ischemia in Mice with Impaired Glucose Tolerance: Shift from Angiogenesis to Axonal Growth and Oxidative Potential in Skeletal Muscle

BACKGROUND

Combined non-viral gene therapy (GT) of ischemia and cardiovascular disease is a promising tool for potential clinical translation. In previous studies our group has developed combined gene therapy by vascular endothelial growth factor 165 (VEGF165) + hepatocyte growth factor (HGF). Our recent works have demonstrated that a bicistronic pDNA that carries both human HGF and VEGF165 coding sequences has a potential for clinical application in peripheral artery disease (PAD). The present study aimed to test HGF/VEGF combined plasmid efficacy in ischemic skeletal muscle comorbid with predominant complications of PAD-impaired glucose tolerance and type 2 diabetes mellitus (T2DM).

METHODS

Male C57BL mice were housed on low-fat (LFD) or high-fat diet (HFD) for 10 weeks and metabolic parameters including FBG level, ITT, and GTT were evaluated. Hindlimb ischemia induction and plasmid administration were performed at 10 weeks with 3 weeks for post-surgical follow-up. Limb blood flow was assessed by laser Doppler scanning at 7, 14, and 21 days after ischemia induction. The necrotic area of m.tibialis anterior, macrophage infiltration, angio- and neuritogenesis were evaluated in tissue sections. The mitochondrial status of skeletal muscle (total mitochondria content, ETC proteins content) was assessed by Western blotting of muscle lysates.

RESULTS

At 10 weeks, the HFD group demonstrated impaired glucose tolerance in comparison with the LFD group. HGF/VEGF plasmid injection aggravated glucose intolerance in HFD conditions. Blood flow recovery was not changed by HGF/VEGF plasmid injection either in LFD or HFD conditions. GT in LFD, but not in HFD conditions, enlarged the necrotic area and CD68+ cells infiltration. However, HGF/VEGF plasmid enhanced neuritogenesis and enlarged NF200+ area on muscle sections. In HFD conditions, HGF/VEGF plasmid injection significantly increased mitochondria content and ETC proteins content.

CONCLUSIONS

The current study demonstrated a significant role of dietary conditions in pre-clinical testing of non-viral GT drugs. HGF/VEGF combined plasmid demonstrated a novel aspect of potential participation in ischemic skeletal muscle regeneration, through regulation of innervation and bioenergetics of muscle. The obtained results made HGF/VEGF combined plasmid a very promising tool for PAD therapy in impaired glucose tolerance conditions.

Healthcare Costs of Diabetes and Microvascular and Macrovascular Disease in Individuals with Incident Type 2 Diabetes Mellitus: A Ten-Year Longitudinal Study

OBJECTIVE

The objective of this study was to estimate the incremental long-term costs associated with T2DM attributable to vascular diseases.

RESEARCH DESIGN AND METHODS

This retrospective cohort study identified newly diagnosed (incident) T2DM patients in 2007 (baseline to 01/01/2006) using the HealthCore Integrated Research Database, a repository of nationally representative claims data. Incident T2DM patients were 1:1 exact matched on age, gender and other factors of interest to non-DM patients, and followed until the earlier of 8 follow-up years or death. Patients with documented vascular disease diagnosis were identified during the study period. All-cause and T2DM/vascular disease-related annual healthcare costs were examined for each follow-up year.

RESULTS

The study included 13,883 individuals with T2DM and matched non-DM controls. Among individuals with T2DM, 11,792 (85%) had vascular disease versus 9251 (66.6%) non-T2DM between 01/01/2006 and 12/31/2015. Among T2DM patients, mean all-cause annual costs were greater than in non-T2DM patients ($13,806 vs $7,243, baseline, $21,745 vs $8,524, post-index year 1, $12,756-$14,793 vs $8,349-$9,940 years 2-8, p< 0.001), respectively. A similar trend was observed for T2DM/vascular disease-related costs (p< 0. 001). T2DM/vascular disease-related costs were largest during post-index year 1, accounting for the majority of all-cause cost difference between T2DM patients and matched non-DM controls. Incident T2DM individuals without vascular disease at any time had significantly lower costs compared to non-DM controls (p< 0. 001) between years 2-8 of follow-up.

CONCLUSION

Vascular disease increased the cost burden for individuals with T2DM. The cost impact of diabetes and vascular disease was highest in the year after diagnosis, and persisted for at least seven additional years, while the cost of T2DM patients without vascular disease trended lower than for matched non-DM patients. These data highlight potential costs that could be offset by earlier and more effective detection and management of T2DM aimed at reducing vascular disease burden.

Impact of obesity on walking capacity and cardiovascular parameters in patients with peripheral artery disease: A cross-sectional study

BACKGROUND

Patients with peripheral artery disease (PAD) present a high prevalence of obesity and metabolic syndrome, as well as diseases related to cardiovascular dysfunction. However, whether obesity influences walking capacity and cardiovascular function in patients with PAD is poorly understood.

OBJECTIVES

The objective of this study was to analyze the impact of obesity on walking capacity and cardiovascular parameters in patients with PAD.

DESIGN

This is a cross-sectional study.

SETTING

Patients were recruited from public hospitals of São Paulo.

METHODS

One-hundred two patients with PAD and symptoms of intermittent claudication were recruited and divided into 2 groups according to their body mass index: normal weight (<25 kg/m²) and overweight/obese (≥25 kg/m²). Patients were submitted to objective (6-minute walk test) and subjective measurements of walking capacity (Walking Impairment Questionnaire). In addition, cardiovascular parameters (office blood pressure, resting heart rate, arterial stiffness, vascular function, and heart rate variability) were obtained.

RESULTS

The speed domain of the Walking Impairment Questionnaire was lower in the overweight/obese group compared to the normal weight group (32 ± 20 vs 21 ± 16, respectively, P < .01). Resting heart rate was higher in overweight/obese patients (61 ± 10 vs 70 ± 12, respectively, P < .01). However, no other walking capacity or cardiovascular parameter variables were related to obesity in patients with PAD.

CONCLUSION

Obesity influences resting heart rate and walking speed in patients with PAD.

Associations of Weight Change With Changes in Calf Muscle Characteristics and Functional Decline in Peripheral Artery Disease

Background

Among people with lower extremity peripheral artery disease, obesity is associated with faster functional decline than normal weight. The association of weight loss with functional decline in peripheral artery disease is unknown.

Methods and Results

Adults with an ankle‐brachial index <0.90 were identified from Chicago‐area hospitals in 2002–2004. Weight and 6‐minute walk distance were measured annually. Weight change categories were weight loss or gain (≥5 pounds/year at ≥1 visit) or stable (weight change <5 pounds at each visit). Participants reported whether weight loss was “intentional” or “unintentional.” Calf muscle area was measured with computed tomography every 2 years. Associations of weight change with changes in calf muscle area and 6‐minute walk distance were analyzed using mixed‐effects models and adjusted for age, body mass index, ankle‐brachial index, physical activity, and other confounders. Among 389 participants, mean ankle‐brachial index was 0.63±0.16, mean age was 74.5±7.8, and mean body mass index was 28.1±5.1 kg/m². Over 3.23±1.37 years, muscle area declined more in adults with intentional weight loss versus stable or gain (pair‐wise comparisons, P<0.001). Intentional weight loss was associated with less annual decline in 6‐minute walk distance than weight gain (intentional loss, 3.7 m; stable, –14.0 m; gain, −28.5 m; unintentional loss, −20.8 m; pair‐wise comparison intentional loss versus gain, P=0.003).

Conclusions

Despite a greater loss of calf muscle area, adults with peripheral artery disease who intentionally lost ≥5 pounds experienced less functional decline than those who gained weight. A randomized trial is needed to establish whether benefits of weight loss in peripheral artery disease outweigh potential adverse effects.

See Editorial Kokkinidis et al

Incidence and Prevalence of Microvascular and Macrovascular Diseases and All-cause Mortality in Type 2 Diabetes Mellitus: A 10-year Study in a US Commercially Insured and Medicare Advantage Population

PURPOSE

The relationship between type 2 diabetes mellitus (T2DM) and increased microvascular and macrovascular disease and mortality is well established; however, data for the broad US T2DM population, especially by age, are limited. To help address this issue, we conducted a cohort study in a large national US commercially insured/Medicare Advantage population that incorporated a broad range of different age groups, including a large subset of younger individuals, during a 10-year study period.

METHODS

This longitudinal study combined health plan claims and mortality data to identify incident T2DM patients and 1:1 directly matched non-DM controls. T2DM individuals (n = 13,883) were identified by a medical claim with a T2DM diagnosis or T2DM medication pharmacy claim in 2007; non-DM controls had no DM medical or pharmacy claims over the entire study period (January 1, 2006 to December 31, 2015). The outcomes assessed were incidence, prevalence, time to vascular disease and all-cause mortality, as well as age-stratified incidence and mortality based on Centers of Disease Control and Prevention-defined age strata.

FINDINGS

Individuals with T2DM developed vascular disease at twice the rate as non-DM controls, 197 versus 98 per 1000 person-years, respectively. Vascular disease (composite) rates increased by age in T2DM/non-DM groups, 107.1/28.2 (18-44 years), 166.3/70.3 (45-64 years), and 391.0/199.7 (≥65 years) per 1000 person-years. The largest rate ratio was observed in younger individuals. All-cause mortality over follow-up was higher in T2DM individuals (27.5%) than in non-DM controls (19.6%). The largest increases in vascular disease prevalence and mortality among T2DM individuals were observed in the first year of follow-up.

IMPLICATIONS

T2DM has a substantial effect on microvascular and macrovascular disease and all-cause mortality rates in all age groups. These outcomes appear to occur early after T2DM diagnosis, and have more pronounced, nearly fourfold, relative impact on younger individuals with T2DM compared to matched non-DM controls.

Body-weight goals, trends, and weight-loss techniques among patients with peripheral arterial disease

BACKGROUND:

Obesity contributes to negative outcomes in peripheral arterial disease (PAD). Little is known about the body-weight goals and trends among patients with PAD.

AIM:

The aim of this study was to explore self-reported body-weight trends and methods used to achieve weight loss in patients with PAD.

METHODS:

Data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES) was utilized to compare individuals with PAD who were overweight and obese ( n = 240), to matched individuals without PAD ( n = 480). Self-reported body weight at age 25 years, 10 years prior and 1 year prior to the current assessment, and age and weight of heaviest body weight were compared. Self-reported weight-loss techniques during the past year were compared between groups.

RESULTS:

Individuals with PAD and controls reported similar weights 10 years prior (79.2 kg vs 78.5 kg; p = 0.60) and weight gain over the last 10 years of 5.7 kg. There was no significant difference in reported body weight at age 25 years, 10 years prior, 1 year prior, or heaviest weight. Compared with the control group, fewer participants with PAD reported attempted weight loss in the last year (27.50% vs 36.04%; p = 0.02) and were half as likely to report utilizing exercise as a weight-loss method (12.5% vs 21.7%; p = 0.003).

CONCLUSIONS:

These data indicate that those with PAD are less inclined to attempt weight loss, especially through means of increased physical activity. Future research is needed regarding the effectiveness of intentional weight-loss programs in this population.

Obesity paradox in peripheral artery disease

BACKGROUND & AIMS

Previous studies have suggested an obesity survival paradox in patients with peripheral artery disease (PAD). We investigated the influence of obesity and underweight on adverse in-hospital outcomes in PAD.

METHODS

Patients diagnosed with PAD based on ICD-code I70.2 of the German nationwide database were stratified for obesity, underweight and a reference group with normal-weight/over-weight and compared regarding adverse in-hospital outcomes.

RESULTS

Between 01/2005-12/2015, 5,611,484 inpatients (64.8% males) were diagnosed with PAD; of those, 8.9% were coded with obesity and 0.3% with underweight. Obese patients were younger (70 (IQR 63/76) vs. 73 (66/80) years, P < 0.001), more frequently female (36.7% vs. 35.1%, P < 0.001), had less cancer (4.9% vs. 7.9%, P < 0.001) and had less treatment with major amputation (2.6% vs. 3.2%, P < 0.001) compared to the reference group. Overall, 277 876 (5.0%) patients died in-hospital. Obese patients showed lower mortality rate (3.2% vs. 5.1%, P < 0.001) compared to the reference group and reduced risk of in-hospital mortality (OR, 0.617 [95%CI 0.607-0.627], P < 0.001). This "obesity paradox" was demonstrated in obesity classes I (OR, 0.475 [95%CI 0.461-0.490], P < 0.001), II (OR, 0.580 [95%CI 0.557-0.605], P < 0.001), and III (OR, 0.895 [95%CI 0.857-0.934], P < 0.001) and was independent of age, sex and comorbidities. Underweight patients revealed higher in-hospital mortality (6.0% vs. 5.1%, P < 0.001) compared to the reference group (OR, 1.179 [95%CI 1.106-1.257], P < 0.001) and showed higher prevalence of cancer (22.0% vs. 7.9%, P < 0.001).

CONCLUSIONS

Coding for obesity is associated with lower in-hospital mortality in PAD patients relative to those with normal-weight/over-weight. This obesity survival paradox was independent of age, gender and comorbidities and observed for all obesity classes.

Changes in Function After a 6-Month Walking Intervention in Patients With Intermittent Claudication Who Are Obese or Nonobese

BACKGROUND AND PURPOSE

Both obesity and peripheral artery disease (PAD) limit function and may work additively to reduce mobility. The purpose of this study was to compare the effects of a 6-month, center-based walking program on mobility function between adults who are weight-stable obese and nonobese with PAD.

METHODS

This is a secondary data analysis of 2 combined studies taken from previous work. Fifty-three adults with PAD and intermittent claudication participated in 6 months of treadmill training or standard of care. Patients were divided into 4 groups for analyses: exercise nonobese (Ex), exercise obese (ExO), standard-of-care nonobese (SC), and standard-of-care obese (SCO). Mobility was assessed by a standardized treadmill test to measure claudication onset time (COT) and peak walking time (PWT) as well as the distance walked during a 6-minute walk distance (6MWD) test.

RESULTS

There was a significant (P < .001) interaction (intervention × obesity) effect on 6MWD, wherein both exercise groups improved (Ex = 7%, ExO = 16%; P < .02), the SC group did not change (0.9%; P > .05), and the SCO group tended to decline (-18%; P = .06). Both exercise intervention groups significantly improved COT (Ex = 92%, ExO = 102%; P < .01) and PWT (Ex = 54%, ExO = 103%; P < .001). There was no change (P > .05) in either standard-of-care group.

CONCLUSIONS

Individuals who are obese and nonobese with PAD made similar improvements after a 6-month, center-based walking program. However, patients who are obese with PAD and do not exercise may be susceptible to greater declines in mobility. Exercise may be particularly important in patients who are obese with PAD to avoid declines in mobility.

Joint Association of Obesity and Hypertension with Disability in the Elderly-- A Community-Based Study of Residents in Shanghai, China

BACKGROUND

Although both obesity and hypertension are known risk factors for disability, the joint association of obesity and hypertension with risk of disability is unknown. This paper is aim to examine the joint association of obesity and hypertension with risk of disability.

METHODS

Cross-sectional study with 8060 elderly community-dwelling individuals participating in the survey initiated by Shanghai Health and Family Planning Commission from March to September 2013. Obesity was measured using the body mass index (BMI) in World Health Organization (WHO) Asia criteria. Hypertension, based on the doctor's diagnosis, was obtained through face-to-face interview. Disability was measured using the self-reported physical self-maintenance scale (PSMS) and the instrumental activities of daily living (IADL) scale developed by Lawton and Brody.

RESULTS

A total of 8.97% of participants reported ADL disability, and 15.18% for IADL disability. After adjusting social demographics and chronic conditions, the risk of ADL disability was progressively greater in obese persons with hypertension (OR=1.40, 95% CI=1.05-1.89), underweight persons without hypertension (OR=2.05, 95% CI=1.29-3.25), and underweight persons with hypertension (OR=2.14, 95% CI=1.36-3.36). For IADL disability, only underweight persons with hypertension were significantly associated (OR=1.65, 95% CI=1.23-2.21).

CONCLUSIONS

Low or extremely high BMI, independent of its metabolic consequences, is a risk factor for disability among the elderly. Simple hypertension wasn't significantly associated with disability. In addition, having hypertension significantly increased the risk of ADL disability in obese individuals and IADL disability in underweight individuals.

Predictors of Improved Walking after a Supervised Walking Exercise Program in Men and Women with Peripheral Artery Disease

We compared the changes in ambulatory outcomes between men and women with symptomatic peripheral arterial disease (PAD) following completion of a supervised, on-site, treadmill exercise program, and we determined whether exercise training variables and baseline clinical characteristics were predictive of changes in ambulatory outcomes in men and women. Twenty-three men and 25 women completed the supervised exercise program, consisting of intermittent walking to mild-to-moderate claudication pain for three months. Men and women significantly increased claudication onset time (COT) (p < 0.001 and p < 0.01, resp.) and peak walking time (PWT) (p < 0.001 for each group). However, change in PWT was less in women (54%) than in men (77%) (p < 0.05). Neither group significantly changed 6-minute walk distance (6MWD). In women, baseline COT was the only predictor for the change in COT (p = 0.007) and the change in PWT (p = 0.094). In men, baseline COT (p < 0.01) and obesity (p < 0.10) were predictors for the change in COT, and obesity was the only predictor for the change in PWT (p = 0.002). Following a supervised, on-site, treadmill exercise program, women had less improvement in PWT than men, and neither men nor women improved submaximal, overground 6MWD. Furthermore, obese men and patients with lower baseline COT were least responsive to supervised exercise. This trial is registered with ClinicalTrial.gov, unique identifier: NCT00618670.

Body composition and ankle-brachial index in Ghanaians with asymptomatic peripheral arterial disease in a tertiary hospital

BACKGROUND

Ankle-brachial index (ABI) and indices of obesity are both use to indicate cardiovascular risk. However, association between body composition indices and ABI, a measure of peripheral arterial disease, is inconsistent in various study reports. In this study, we investigated the relationship between ABI and general and central indices of obesity in Ghanaians without history of cardiovascular diseases.

METHOD

In a case-control design, ABI was measured in a total of 623 subjects and categorised into PAD (ABI ≤ 0.9, n = 261) and non-PAD (ABI > 0.9, n = 362) groups. Anthropometric indices, BMI, waist circumference (WC), waist-hip ratio (WHR) and waist-height ratio (WHtR) were also measured.

RESULTS

PAD subjects had higher mean BMI (29.8 ± 8.7 vs. 26.5 ± 7.6 kg/m(2), p = 0.043) and waist circumference (95 ± 15 vs. 92 ± 24 cm, p = 0.034) than non-PAD subjects. In multivariable logistic regression models, having BMI ≥ 30 kg/m(2) increased the odds of both unilateral [OR (95 % CI): 2 (1.14-3.51), p < 0.01] and overall PAD [2 (1.22-3.27), p < 0.01].

CONCLUSION

In indigenous Ghanaians in our study, PAD participants had higher BMI and waist circumference than non-PAD participants. Also, halving BMI ≥ 30 kg/m(2) was associated with twofold increase in the odds of PAD.

Spatiotemporal Changes Posttreatment in Peripheral Arterial Disease

Accumulating evidence suggests revascularization of peripheral arterial disease (PAD) limbs results in limited improvement in functional gait parameters, suggesting underlying locomotor system pathology. Spatial and temporal (ST) gait parameters are well studied in patients with PAD at baseline and are abnormal when compared to controls. The purpose of this study was to systematically review and critically analyze the available data on ST gait parameters before and after interventions. A full review of literature was conducted and articles were included which examined ST gait parameters before and after intervention (revascularization and exercise). Thirty-three intervention articles were identified based on 154 articles that evaluated ST gait parameters in PAD. Four articles fully assessed ST gait parameters before and after intervention and were included in our analysis. The systematic review of the literature revealed a limited number of studies assessing ST gait parameters. Of those found, results demonstrated the absence of improvement in gait parameters due to either exercise or surgical intervention. Our study demonstrates significant lack of research examining the effectiveness of treatments on ST gait parameters in patients with PAD. Based on the four published articles, ST gait parameters failed to significantly improve in patients with PAD following intervention.

Clinical predictors of ventilatory threshold achievement in patients with claudication

PURPOSE

Ventilatory threshold (VT) is considered a clinically important marker of cardiovascular function in several populations, including patients with claudication, because it is related to walking capacity and hemodynamics. The purpose of this study was to identify clinical predictors for VT achievement in patients with intermittent claudication.

METHODS

One hundred and seventy-seven (n = 177) patients with intermittent claudication performed a progressive graded cardiopulmonary treadmill test until maximal claudication pain. Oxygen uptake (V˙O2) was continuously measured during the test, and afterwards, VT was visually detected. Clinical characteristics, demographic data, comorbid conditions, and cardiovascular risk factors were obtained. Patients who achieved and did not achieve VT were compared, as well as the workload that VT occurred in the former group.

RESULTS

VT was achieved in 134 patients (76%), and the mean V˙O2 at VT for these patients was 10.8 ± 2.4 mL·kg(-1)·min(-1). Patients who did not achieve VT presented lower ankle brachial index (ABI), claudication onset time, peak walking time, and V˙O2peak, and the proportion of women was higher compared with patients who achieved VT (P < 0.05). Multiple linear regression analysis identified that sex (b = 0.25, P = 0.002), body mass index (b = -0.18, P = 0.025), peak walking time (b = 0.17, P = 0.044), and ABI (b = 0.23, P = 0.006) were predictors of V˙O2 at VT.

CONCLUSIONS

Forty-three patients (24%) with intermittent claudication did not achieve VT, and these patients were mostly women and those with greater severity of disease. Moreover, in those who reached VT, the predictors of poor VT were female sex, high body mass index, low peak walking time, and low ABI.

Influence of regular exercise on body fat and eating patterns of patients with intermittent claudication

This study examined the impact of regular supervised exercise on body fat, assessed via anthropometry, and eating patterns of peripheral arterial disease patients with intermittent claudication (IC). Body fat, eating patterns and walking ability were assessed in 11 healthy adults (Control) and age- and mass-matched IC patients undertaking usual care (n = 10; IC-Con) or supervised exercise (12-months; n = 10; IC-Ex). At entry, all groups exhibited similar body fat and eating patterns. Maximal walking ability was greatest for Control participants and similar for IC-Ex and IC-Con patients. Supervised exercise resulted in significantly greater improvements in maximal walking ability (IC-Ex 148%-170% vs. IC-Con 29%-52%) and smaller increases in body fat (IC-Ex -2.1%-1.4% vs. IC-Con 8.4%-10%). IC-Con patients exhibited significantly greater increases in body fat compared with Control at follow-up (8.4%-10% vs. -0.6%-1.4%). Eating patterns were similar for all groups at follow-up. The current study demonstrated that regular, supervised exercise significantly improved maximal walking ability and minimised increase in body fat amongst IC patients without changes in eating patterns. The study supports the use of supervised exercise to minimize cardiovascular risk amongst IC patients. Further studies are needed to examine the additional value of other lifestyle interventions such as diet modification.

Impact of weight loss on ankle-brachial index and interartery blood pressures

OBJECTIVE

To assess whether weight loss improves markers of peripheral artery disease and vascular stenosis.

METHODS

The Action for Health in Diabetes randomized clinical trial compared intensive lifestyle intervention (ILI) for weight loss to a control condition of diabetes support and education (DSE) in overweight or obese adults with type 2 diabetes. Annual ankle and brachial blood pressures over four years were used to compute ankle-brachial indices (ABIs) and to assess interartery blood pressure differences in 5018 participants.

RESULTS

ILI, compared to DSE, produced 7.8% (Year 1) to 3.6% (Year 4) greater weight losses. These did not affect prevalence of low (<0.90) ABI (3.60% in DSE versus 3.14% in ILI; P = 0.20) or elevated (>1.40) ABI (7.52% in DSE versus 7.59% in ILI: P = 0.90), but produced smaller mean (SE) maximum interartery systolic blood pressure differences among ankle sites [19.7 (0.2) mmHg for ILI versus 20.6 (0.2) mmHg for DSE (P < 0.001)] and between arms [5.8 (0.1) mmHg for ILI versus 6.1 (0.1) mmHg for DSE (P = 0.01)].

CONCLUSIONS

Four years of intensive behavioral weight loss intervention did not significantly alter prevalence of abnormal ABI, however, it did reduce differences in systolic blood pressures among arterial sites.

Prevalence and risk factors of asymptomatic peripheral arterial disease in patients with COPD in Taiwan

AIM

Chronic obstructive pulmonary disease (COPD) is an independent risk factor for cardiovascular morbidity and mortality. The aim of this study was to determine the prevalence of asymptomatic peripheral arterial disease (PAD) and the associated risk factors for patients with COPD.

METHODS

This prospective cross-sectional study enrolled 427 COPD patients (mean age: 70.0 years) without PAD symptoms consecutively. Demographic data, lung function and cardiovascular risk factors were recorded. The ankle-brachial index (ABI) was used to detect PAD (ABI<0.90).

RESULTS

The overall prevalence of asymptomatic PAD in the COPD patients was 8% (2.5% in the younger participants (<65 years of age, n = 118) and 10% in the elderly participants (≥65 years of age, n = 309). The COPD patients with asymptomatic PAD had a significantly higher rate of hyperlipidemia (47.1% vs. 10.4%) and hypertension (79.4% vs. 45.8%) than those without asymptomatic PAD (p<0.05). There was no significant difference in lung function (forced vital capacity and forced expiratory volume in one second) between the two groups. In multivariate logistic regression, hyperlipidemia was the strongest independent factor for PAD (odds ratio (OR): 6.89, p<0.005), followed by old age (OR: 4.80), hypertension (OR: 3.39) and smoking burden (pack-years, OR: 1.02).

CONCLUSIONS

The prevalence of asymptomatic PAD among COPD patients in Taiwan is lower than in Western countries. Hyperlipidemia, old age, hypertension, and smoking burden were the associated cardiovascular risk factors. However, there was no association between lung function and PAD in the COPD patients.

The role of nutrition and body composition in peripheral arterial disease

Peripheral arterial disease (PAD) has not been as extensively investigated as other cardiovascular diseases. However, the available data suggest that nutrition-based treatment strategies have the potential to reduce the cost-economic burden of PAD substantially. Abdominal obesity is associated with PAD and prospective and cross-sectional studies have shown that a low dietary intake of folate and reduced synthesis of vitamin D are associated with an increased risk of PAD and severe walking impairment in patients who have the disease. However, dietary patterns that are associated with decreased cardiovascular risk might protect against PAD. A small number of clinical trials have provided evidence that increased intakes of niacin and insoluble fiber might be associated with decreased levels of LDL cholesterol and thrombogenic biomarkers, as well as increased serum levels of HDL cholesterol in patients with PAD. However, little evidence that antioxidants, vitamins B(6) and B(12), or essential fatty acid supplements improve clinical outcomes in these patients exists. Overall, data on the effects of nutrition, body composition, and nutritional supplementation on the risk, progression, and prognosis of PAD are scarce. Further research into these areas is required to allow the development of evidence-based nutritional guidelines for the prevention and treatment of the disease.

Higher body mass index is associated with more adverse changes in calf muscle characteristics in peripheral arterial disease

OBJECTIVE

This study investigated whether higher body mass index (BMI) is associated with more adverse lower extremity muscle characteristics at baseline and more adverse changes in muscle over time among participants with lower extremity peripheral arterial disease (PAD).

METHODS

This was a longitudinal, observational study of 425 men and women with PAD and 261 without PAD. Computed tomography was used to measure calf muscle characteristics at baseline and every 2 years. Knee extension isometric strength, power, and 6-minute walk distance were measured at baseline and annually. Baseline BMI (kg/m(2)) categories were ideal (20-25), overweight (>25-30), and obese (>30). Analyses adjust for age, race, sex, ankle brachial index, comorbidities, and other covariates.

RESULTS

At baseline, higher BMI among participants with PAD was associated with greater calf muscle area (ideal BMI: 5181 mm(2); overweight: 5513 mm(2); obese: 5695 mm(2); P = .0009 for trend), higher calf muscle percentage of fat (6.38%, 10.28%, 17.44%, respectively, P < .0001 for trend), lower calf muscle density (P < .0001 for trend), and higher isometric knee extension strength (P = .015 for trend). Among participants with PAD, higher BMI was associated with greater declines in calf muscle area (P = .030 for trend) and greater increases in calf muscle percentage of fat (P = .023 for trend). Among participants without PAD, there were no significant associations of baseline BMI with changes in lower extremity muscle outcomes over time.

CONCLUSIONS

Among PAD participants, higher BMI is associated with greater calf muscle area at baseline. However, higher BMI is associated with more adverse calf muscle density and calf muscle percentage of fat at baseline and greater declines in calf muscle area over time.

Obesity, intentional weight loss and physical disability in older adults

We examine obesity, intentional weight loss and physical disability in older adults. Based on prospective epidemiological studies, body mass index exhibits a curvilinear relationship with physical disability; there appears to be some protective effect associated with older adults being overweight. Whereas the greatest risk for physical disability occurs in older adults who are ≥class II obesity, the effects of obesity on physical disability appears to be moderated by both sex and race. Obesity at age 30 years constitutes a greater risk for disability later in life than when obesity develops at age 50 years or later; however, physical activity may buffer the adverse effects obesity has on late life physical disability. Data from a limited number of randomized clinical trials reinforce the important role that physical activity plays in weight loss programmes for older adults. Furthermore, short-term studies have found that resistance training may be particularly beneficial in these programmes as this mode of exercise attenuates the loss of fat-free mass during caloric restriction. Multi-year randomized clinical trials are needed to examine whether weight loss can alter the course of physical disablement in aging and to determine the long-term feasibility and effects of combining resistance exercise with weight loss in older adults.

Activated protein C-protein C inhibitor complex in peripheral arterial disease

BACKGROUND

Thrombin activation measured by the levels of the complex between activated protein C (APC) and the protein C inhibitor (PCI) is elevated in several atherosclerotic disorders. The aim of this study was to evaluate whether levels of the APC-PCI complex are related to the prognosis in peripheral arterial disease (PAD). Longitudinal study performed at the Vascular Centre, Malmö University Hospital, Sweden.

METHODS

APC-PCI complex levels were analyzed in 268 consecutive patients hospitalized for PAD and in 42 healthy controls (median age, 74 years). Patients (n = 35) with warfarin treatment less than 4 weeks before APC-PCI sampling were excluded from analysis. Data-based medical records of all 233 remaining patients (median age, 72 [64-79] years) were searched for vascular events such as hospitalization because of atherosclerotic disease, operative or endovascular recanalization of peripheral arteries, transtibial or transfemoral amputation because of PAD, acute coronary syndrome, stroke, or death.

RESULTS

Median duration of follow-up was 16 months (interquartile range, 12-23 months). APC-PCI complex levels were higher in PAD patients than in controls (0.240 [0.180-0.320] microg/L vs. 0.140 [0.190-0.220] microg/L; p < 0.0001) but not associated with an increased risk for death (p = 0.2054) or events during follow-up (p = 0.2850). Independent predictors of future events were low b-hemoglobin (p = 0.0084), high b-leukocytes (p = 0.0034), and history of a previous vascular event (p = 0.0032). Age (p = 0.0286), high p-creatinine (p = 0.0165), and history of a previous event (p = 0.0311) were independent predictors of death.

CONCLUSION

APC-PCI complex levels were higher in PAD patients than in controls, but did not predict the clinical outcome. The effect of a possible prethrombotic state, as reflected in increased APC-PCI levels, on prognosis and severity of atherosclerotic disease has to be further investigated.

Associations of borderline and low normal ankle-brachial index values with functional decline at 5-year follow-up: the WALCS (Walking and Leg Circulation Study)

OBJECTIVES

We studied associations of borderline and low normal ankle-brachial index (ABI) values with functional decline over a 5-year follow-up.

BACKGROUND

The associations of borderline and low normal ABI with functional decline are unknown.

METHODS

The 666 participants included 412 with peripheral arterial disease (PAD). Participants were categorized as follows: severe PAD (ABI <0.50), moderate PAD (ABI 0.50 to 0.69), mild PAD (ABI 0.70 to 0.89), borderline ABI (0.90 to 0.99), low normal ABI (1.00 to 1.09), and normal ABI (ABI 1.10 to 1.30). Outcomes were assessed annually for 5 years. Mobility loss was defined as loss of the ability to walk one-quarter mile or walk up and down 1 flight of stairs without assistance among participants without baseline mobility impairment. Becoming unable to walk for 6 min continuously was defined as stopping during the 6-min walk at follow-up among those who walked for 6 min continuously at baseline. Results were adjusted for age, sex, race, comorbidities, and other confounders.

RESULTS

Hazard ratios (HRs) for mobility loss according to ABI category were as follows: severe PAD, HR: 4.16 (95% confidence interval [CI]: 1.58 to 10.92); moderate PAD, HR: 3.82 (95% CI: 1.66 to 8.81); mild PAD, HR: 3.22 (95% CI: 1.43 to 7.21); borderline ABI, HR: 3.07 (95% CI: 1.21 to 7.84); and low normal ABI, HR: 2.61 (95% CI: 1.08 to 6.32; p trend = 0.0018). Similar associations were observed for becoming unable to walk for 6 min continuously (p trend < 0.0001).

CONCLUSIONS

At 5-year follow-up, persons with borderline ABI values have a higher incidence of mobility loss and becoming unable to walk for 6 min continuously compared with persons who have a normal baseline ABI. A low normal ABI is associated with an increased incidence of mobility loss compared with persons who have a normal ABI.

Recruiting participants with peripheral arterial disease for clinical trials: experience from the Study to Improve Leg Circulation (SILC)

OBJECTIVE

To describe the success of diverse recruitment methods in a randomized controlled clinical trial of exercise in persons with peripheral arterial disease (PAD).

METHODS

An analysis of recruitment sources conducted for the 746 men and women completing a baseline visit for the study to improve leg circulation (SILC), a randomized controlled trial of exercise for patients with PAD. For each recruitment source, we determined the number of randomized participants, the rate of randomization among those completing a baseline visit, and cost per randomized participant.

RESULTS

Of the 746 individuals who completed a baseline visit, 156 were eligible and randomized. The most frequent sources of randomized participants were newspaper advertising (n = 67), mailed recruitment letters to patients with PAD identified at the study medical center (n = 25), and radio advertising (n = 18). Costs per randomized participant were $2750 for television advertising, $2167 for Life Line Screening, $2369 for newspaper advertising, $3931 for mailed postcards to older community dwelling men and women, and $5691 for radio advertising. Among those completing a baseline visit, randomization rates ranged from 10% for those identified from radio advertising to 32% for those identified from the Chicago Veterans Administration and 33% for those identified from posted flyers.

CONCLUSION

Most participants in a randomized controlled trial of exercise were recruited from newspaper advertising and mailed recruitment letters to patients with known PAD. The highest randomization rates after a baseline visit occurred among participants identified from posted flyers and mailed recruitment letters to PAD patients.

Corridor-based functional performance measures correlate better with physical activity during daily life than treadmill measures in persons with peripheral arterial disease

OBJECTIVE

To compare associations of physical activity during daily life with treadmill walking performance and corridor-based functional performance measures in persons with lower extremity peripheral arterial disease (PAD).

STUDY DESIGN

Cross-sectional.

SUBJECTS

One hundred fifty-six men and women with PAD who completed baseline measurements and were randomized into the study to improve leg circulation (SILC) exercise clinical trial.

MAIN OUTCOME MEASURES

Participants completed a Gardner-Skinner treadmill protocol. Corridor-based functional performance measures were the 6-minute walk, walking velocity over four meters at usual and fastest pace, and the short physical performance battery (SPPB) (0-12 scale, 12 = best). Physical activity during daily life was measured continuously over 7 days with a Caltrac (Muscle Dynamics Fitness Network, Inc, Torrence, Calif) accelerometer.

RESULTS

Adjusting for age, gender, and race, higher levels of physical activity during daily life were associated with greater distance achieved in the 6-minute walk (P trend = .001), faster fast-paced four-meter walking velocity (P trend < .001), faster usual-paced four-meter walking speed (P trend = .027) and a higher SPPB (P trend = .005). The association of physical activity level with maximum treadmill walking distance did not reach statistical significance (P trend = .083). There were no associations of physical activity with treadmill distance to onset of leg symptoms (P trend = .795).

CONCLUSION

Functional performance measures are more strongly associated with physical activity levels during daily life than treadmill walking measures.

Persistent depressive symptoms and functional decline among patients with peripheral arterial disease

OBJECTIVE

Because depressive symptoms are prevalent among patients with peripheral arterial disease (PAD), our goal was to study the effect of depressive symptoms over time on functional decline among patients with PAD.

METHODS

We conducted a prospective cohort study of 417 patients with PAD followed annually for 2 years. A Geriatric Depression Scale Short Form (GDS-S) score >5 was considered positive for depressive symptoms. Depressive symptom categories based on annual GDS-S measures included persistent, new, resolved, and no depressive symptoms. Outcome variables were change in 6-minute walk distance, 4-meter fast walking velocity, and short physical performance battery (0-12 scale, 12 = best). Results are adjusted for age, sex, race, body mass index, marital status, exercise level, smoking, ankle brachial index, leg symptoms, comorbidities, beta-blocker medication use, anti-depressant medications, and interim medical events.

RESULTS

In adjusted analyses, patients with new depressive symptoms had greater annual decline in fast walking velocity compared with that of patients with no depressive symptoms (-0.08 versus -0.01 meters/second per year, p = .02). Patients with persistent depressive symptoms had greater annual decline in 6-minute walk distance (-86.4 versus -41.5 feet/yr, p = .04), fast walking velocity (-0.08 versus -0.01 meters/second per year, p = .004), and short physical performance battery (-0.73 versus -0.18 per year, p = .005) compared with that of patients with no depressive symptoms.

CONCLUSIONS

Among patients with PAD, persistent and new depressive symptoms are associated with greater annual decline in functional performance. Further study is needed to determine the mechanisms of these associations and whether treatment of depressive symptoms prevents functional decline in persons with PAD.

Physical activity, walking exercise, and calf skeletal muscle characteristics in patients with peripheral arterial disease

OBJECTIVE

This cross-sectional study was set in an academic medical center and conducted to identify associations of physical activity level and walking exercise frequency with calf skeletal muscle characteristics in individuals with lower extremity peripheral arterial disease (PAD).

METHODS

Calf muscle characteristics in 439 men and women with PAD were measured with computed tomography at 66.67% of the distance between the distal and proximal tibia. Physical activity was measured continuously during 7 days with a vertical accelerometer. Patient report was used to determine the number of blocks walked during the past week and walking exercise frequency. Results were adjusted for age, sex, race, comorbidities, ankle-brachial index, body mass index, smoking, and other confounders.

RESULTS

For both objective and subjective measures, more physically active PAD participants had higher calf muscle area and muscle density. Calf muscle area across tertiles of accelerometer-measured physical activity were first activity tertile, 5071 mm(2); second activity tertile: 5612 mm(2); and third activity tertile, 5869 mm(2) (P < .001). Calf muscle density across tertiles of patient-reported blocks walked during the past week were first activity tertile, 31.4 mg/cm(3); second activity tertile, 33.0 mg/cm(3); and third activity tertile, 33.8 mg/cm(3) (P < .001). No significant associations were found between walking exercise frequency and calf muscle characteristics.

CONCLUSION

Among participants with PAD, higher physical activity levels, measured by accelerometer and by patient-reported blocks walked per week, were associated with more favorable calf muscle characteristics. In contrast, more frequent patient-reported walking exercise was not associated with more or less favorable calf muscle characteristics. Results suggest that clinicians should encourage their patients to increase their walking activity during daily life.