Journal of Vascular Surgery
Volume 43, Issue 6 , Pages 1191-1196, June 2006

Metabolic syndrome impairs physical function, health-related quality of life, and peripheral circulation in patients with intermittent claudication

  • Andrew W. Gardner, PhD

      Affiliations

    • CMRI Metabolic Research Center, University of Oklahoma Health Sciences Center
    • Department of Medicine, Division of Gerontology, University of Maryland
    • Maryland Veterans Affairs Health Care System.
    • Corresponding Author InformationReprint requests: Andrew W. Gardner, Ph.D., Hobbs-Recknagel Professor, CMRI Metabolic Research Center, University of Oklahoma Health Sciences Center, 1122 Northeast 13th Street, ORI-W 1400, Oklahoma City, OK 73117.
    • ,
  • Polly S. Montgomery, MS

      Affiliations

    • CMRI Metabolic Research Center, University of Oklahoma Health Sciences Center
    • Department of Medicine, Division of Gerontology, University of Maryland
    • Maryland Veterans Affairs Health Care System.
    • ,
  • Donald E. Parker, PhD

      Affiliations

    • Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center

Received 21 November 2005; accepted 13 February 2006.

Article Outline

Purpose

This study was conducted to (1) examine the effect of metabolic syndrome on intermittent claudication, physical function, health-related quality of life, and peripheral circulation in patients with peripheral arterial disease (PAD), and (2) determine whether peripheral vascular function was predictive of intermittent claudication and physical function in patients with metabolic syndrome.

Methods

Patients limited by intermittent claudication and who had metabolic syndrome (n = 133) were compared with those without metabolic syndrome (n = 201). Patients were assessed on metabolic syndrome characteristics, PAD-specific measures consisting of ankle/brachial index and claudication distances, physical function measures, health-related quality of life, and calf blood flow and transcutaneous oxygen tension responses after 3 minutes of vascular occlusion.

Results

Initial claudication distance (mean ± SD) was 29% shorter (P = .018) in patients with metabolic syndrome than in the controls (128 ± 121 meters vs 180 ± 166 meters), and absolute claudication distance was 22% shorter (P = .025) in those with metabolic syndrome (319 ± 195 meters vs 409 ± 255 meters). Furthermore, patients with metabolic syndrome had lower peak oxygen uptake (P = .037), a shorter 6-minute walk distance (P = .027), lower values on six domains of health-related quality of life (P < .05), reduced calf hyperemia (P = .028), and greater calf ischemia (P < .001) after vascular occlusion. In the group with metabolic syndrome, calf ischemia was correlated with initial claudication distance (r = 0.30, P = .004), absolute claudication distance (r = 0.40, P < .001), and peak oxygen uptake (r = 0.52, P < .001).

Conclusion

Metabolic syndrome worsens intermittent claudication, physical function, health-related quality of life, and peripheral circulation in patients with PAD. Calf ischemia in those with metabolic syndrome was predictive of intermittent claudication and physical function. The additive burden of metabolic syndrome thus places patients who are limited by intermittent claudication at an even greater risk for living a functionally dependent lifestyle. Aggressive risk-factor modification designed to treat components of metabolic syndrome should be evaluated for efficacy in modifying physical and vascular function in patients with intermittent claudication.

 

Peripheral arterial disease (PAD) is a strong prognostic indicator of poor long-term survival1, 2, 3, 4, 5, 6, 7 and is a leading cause of morbidity due to intermittent claudication.8 Intermittent claudication afflicts 5% of the United States population >55 years old9 and occurs during ambulation when the peripheral circulation is inadequate to meet the metabolic requirement of the active leg musculature. Consequently, patients with intermittent claudication have ambulatory dysfunction10, 11, 12, 13 that limits daily physical activities14 and negatively affects health-related quality of life.15

Patients limited by intermittent claudication are at the extreme low end of the physical activity spectrum,16 which may increase their risk of being overweight (body mass index [BMI] ≥25 kg/m2) or obese (BMI ≥30 kg/m2). Thus, PAD patients with intermittent claudication may be susceptible to the development of metabolic syndrome, defined as having three or more of the following criteria: (1) abdominal obesity, (2) hypertriglyceridemia, (3) low high-density lipoprotein cholesterol, (4) hypertension, and (5) fasting glucose ≥110 mg/dL.17

Alternatively, it is equally plausible that patients with metabolic syndrome are susceptible to the development of PAD and intermittent claudication. In either case, patients who have both PAD and metabolic syndrome may have an elevated risk of subsequent cardiovascular morbidity and mortality.18 The impact of metabolic syndrome in patients limited by intermittent claudication is not established, however. The possible negative consequences that metabolic syndrome may have on ambulation and peripheral circulation in this functionally dependent population is of particular importance.

The purposes of this study were to (1) examine the effect of metabolic syndrome on intermittent claudication, physical function, health-related quality of life, and peripheral circulation in patients with PAD, and (2) determine whether peripheral vascular function was predictive of the severity of intermittent claudication in patients with metabolic syndrome. We hypothesized that patients with metabolic syndrome would have shorter claudication distances, worse ambulatory function, lower health-related quality of life related to physical health, and impaired peripheral circulation than patients without metabolic syndrome. We further hypothesized that the peripheral circulation would be predictive of claudication distances and ambulatory function in patients with metabolic syndrome.

Back to Article Outline

Patients and methods 

Screening 

A total of 423 PAD patients with stable symptoms of intermittent claudication were evaluated in the Geriatrics, Research, Education, and Clinical Center at the Maryland Veterans Affairs Health Care System (MVAHCS) at Baltimore. Patients were recruited from the vascular clinic at the site of the Baltimore MVAHCS. Patients were included in this study if they had Fontaine stage II PAD19 defined by the following inclusion criteria: (1) a history of intermittent claudication, (2) ambulation during a graded treadmill test limited by intermittent claudication,20 and (3) an ankle/brachial index (ABI) at rest of <0.90.9 Patients were excluded from this study for the following conditions: (1) absence of PAD, (2) inability to obtain an ABI measure due to noncompressible vessels, (3) asymptomatic PAD (Fontaine stage I), (4) rest pain PAD (Fontaine stage III), (5) use of medications indicated for the treatment of intermittent claudication (cilostazol and pentoxifylline) ≤3 months before the investigation, (6) exercise tolerance limited by factors other than claudication (eg, severe coronary artery disease, dyspnea, poorly controlled blood pressure), and (7) active cancer, renal disease, or liver disease. A total of 334 patients were deemed eligible for this investigation, and 89 patients were ineligible. All patients lived independently at home.

The Institutional Review Boards at the University of Maryland and the MVAHCS at Baltimore approved the procedures used in this study. Written informed consent was obtained from each patient before the investigation.

Metabolic syndrome classification 

According to the National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III,17 metabolic syndrome is defined as having three or more of the following criteria: (1) abdominal obesity (waist circumference >102 cm in men and >88 cm in women), (2) hypertriglyceridemia (≥150 mg/dL), (3) low high-density lipoprotein cholesterol (<40 mg/dL in men and <50 mg/dL in women), (4) blood pressure ≥130/85 mm Hg, and (5) fasting glucose ≥110 mg/dL. Although several definitions of metabolic syndrome exist, the NCEP ATP III definition was used in this investigation because it was specifically established on a population from the United States. In the total group of 334 patients, 133 patients (40%) screened positive for metabolic syndrome, and the remaining 201 patients (60%) screened negative.

In addition to the exclusionary criteria mentioned previously, 68 patients who had diabetes but not metabolic syndrome were excluded from this investigation so that the control group would have a more distinct metabolic profile than the patients with metabolic syndrome. The 40% prevalence of metabolic syndrome in this cohort of PAD patients limited by intermittent claudication is higher than the 23.7% prevalence in the adult population, but similar to the prevalence in those ≥60 years of age.21

Medical history 

Demographic information, height, weight, cardiovascular risk factors, comorbid conditions, claudication history, and a list of current medications were obtained during a physical examination and medical history interview to begin the evaluation.

Ankle/brachial index 

After 10 minutes of supine rest, the ankle and brachial systolic blood pressures were obtained, as previously described.22 The ABI was calculated as ankle systolic pressure/brachial systolic pressure. The test-retest intraclass reliability coefficient is R = 0.96 for ABI.20

Claudication distances and peak oxygen uptake 

Patients performed a progressive, graded treadmill protocol (2 mph, 0% grade with 2% increase every 2 minutes) until maximal claudication pain, as previously described.20 The initial claudication distance (ICD), absolute claudication distance (ACD), and peak oxygen uptake were measured. The test-retest intraclass reliability coefficient with these procedures is R = 0.89 for ICD,20 R = 0.93 for ACD,20 and R = 0.88 for peak oxygen uptake.23

Walking economy and fractional utilization 

Oxygen uptake was measured during a constant, submaximal work rate at a treadmill speed of 2 mph and a grade of 0% until maximal claudication pain or for a maximum of 20 minutes.24 Six patients with metabolic syndrome and 17 patients without metabolic syndrome completed the maximum time limit of 20 minutes of walking. Walking economy was measured as the oxygen uptake obtained during the final minute of the test. To quantify the intensity of the walking economy test as a percentage of peak capacity, fractional utilization was calculated as the walking economy oxygen uptake/peak oxygen uptake.

Six-minute walk test 

Patients performed an over-the-ground 6-minute walk test supervised by trained exercise technicians, as previously described.25 The pain-free and total distance walked during the test were recorded. The test-retest intraclass reliability coefficient is R = 0.75 for the distance to onset of claudication pain and R = 0.94 for the total 6-minute walking distance.25

Walking Impairment Questionnaire 

Self-reported ambulatory ability was assessed by using the Walking Impairment Questionnaire (WIQ), a validated questionnaire for PAD patients that assesses ability to walk at various speeds and distances and to climb stairs.26

Summary performance score 

The summary performance score was calculated from the performance of a 4-meter walk test, a chair stand test, and a standing balance test, as previously described.27, 28 Briefly, during the 4-meter walk test, walking velocity was assessed by measuring the time required for subjects to walk a distance of 4 meters marked out in a corridor at their usual pace. During the chair stand test, lower-extremity strength and balance were assessed by a repeated chair rise test in which patients completed five sequential sit-to-stand transfers from an armless, 18-inch-high, straight-backed chair with their arms folded across their chest. During the standing balance test, balance was assessed by measuring the time that patients could hold a stance in side-by-side, semi-tandem, and full-tandem positions.

For each of the three tests, patients were scored on a 0 to 4 ordinal scale, with a score of 0 representing inability to perform the test, and scores between 1 and 4 representing quartiles of performance based on normative data on more than 5000 community-dwelling people published from the Established Populations for the Epidemiologic Studies of the Elderly.27 The summary performance score ranges from 0 to 12 (0, worst function; 12, best function) and is predictive of mobility loss, nursing home placement, and mortality among community-dwelling elderly individuals.27, 28 The test-retest intraclass reliability coefficient is R = 0.93 for the summary performance score.29

Self-perceived health 

The Health Utilities Index, ranging between 0 (the worst imaginable health) and 100 (the best imaginable health) was used to assess self-reported health as previously described.30 Patients were asked to select a numeric value on the scale that best corresponded to their current overall health state.

Daily physical activity 

Physical activity level was monitored over two consecutive weekdays by a Caltrac accelerometer (Muscle Dynamics, Torrance, Calif) attached to the belt of each subject, as previously described.31 Additionally, a physical activity scale was used to assess the self-reported physical activity level over the preceding month, as previously described.14, 16 The accelerometer measure of physical activity has a test-retest intraclass reliability coefficient of R = 0.8416 and provides a valid estimate of daily physical activity assessed by the gold standard technique of doubly labeled water.31

Quality of life 

Health-related quality of life was assessed with the Medical Outcomes Study Short-Form 36 (MOS SF-36) General Health Survey.32 The MOS SF-36 is a reliable and valid generic instrument that includes multi-item scales measuring the eight health domains of physical function, role limitations due to physical problems, general health, bodily pain, social function, role limitations due to emotional problems, mental health, and vitality. For each subscale, item scores were recorded, summed, and standardized into a scale from 0 to 100, with better health states resulting in higher scores.

Calf blood flow 

Calf blood flow was obtained at rest and after 3 minutes of arterial occlusion (ie, reactive hyperemia) in the more severely diseased leg by using venous occlusion mercury strain-gauge plethysmography, as previously described.33 The test-retest intraclass reliability coefficient is R = 0.86 for calf blood flow.33

Transcutaneous oxygen tension 

Transcutaneous oxygen tension (TcPo2) was measured at rest and after 3 minutes of arterial occlusion on the medial portion of the calf musculature of the more affected leg with a Clark-type polarographic electrode and a TcPo2 Monitor (Novametrix Medical System, Model 840). The change in calf TcPo2 after arterial occlusion is a measure of the ischemic response to this test. The test-retest intraclass reliability coefficient is R = 0.87 for calf TcPo2.23

Statistical analyses 

Unpaired t tests and χ2 tests were used to assess whether differences in the clinical characteristics existed between the patients with and without metabolic syndrome. Analysis of covariance was then used to assess whether group differences in the claudication distances, physical function measures, health-related quality of life, and peripheral vascular measures persisted after controlling for obesity, as measured by BMI. Stepwise multiple regression was then performed to determine whether the peripheral circulation measurements were predictive of ICD and ACD in the patients with metabolic syndrome. All analyses were performed using the SPSS-PC (SPSS Inc, Chicago, Ill) statistical package. Statistical significance was set at P < .05. Measurements are presented as means ± standard deviations.

Back to Article Outline

Results 

The clinical characteristics of the patients with and without metabolic syndrome are presented in Table I. As expected, patients with metabolic syndrome had a greater prevalence (P < .001) of each characteristic of metabolic syndrome (diabetes, hypertension, hyperlipidemia, and abdominal obesity) than those without metabolic syndrome. Additionally, those with metabolic syndrome had a higher body weight (P < .001), BMI (P < .001), and prevalence of obesity (P < .001). The two groups were similar in age, sex, race, ABI, history of intermittent claudication, and prevalence of current smoking (P > .05).

Table I. Clinical characteristics of peripheral arterial disease patients with and without metabolic syndrome
VariablesControl group⁎ (n = 201)Metabolic syndrome group⁎ (n = 133)P
Age (years)67±967±7.702
Weight (kg)78.3±15.389.9±14.8<.001
BMI26.8±4.431.0±4.5<.001
ABI0.70±0.220.67±0.24.165
IC duration (years)4.7±5.24.7±4.2.997
Sex (% men)7978.874
Race (% white)6158.711
Current smoking4642.322
Diabetes071—
Hypertension6395<.001
Hyperlipidemia3987<.001
Abdominal obesity2473<.001
Obesity⁎1657<.001

BMI, Body mass index; ABI, ankle/brachial index; IC, intermittent claudication.

†Obesity was defined as having a body mass index ≥30 kg/m2.

⁎ Values are means ± SD and percentages.

The measurements obtained during standardized treadmill tests in the patients with and without metabolic syndrome are listed in Table II. Those with metabolic syndrome had shorter ICD (P = .018) and ACD (P = .025), lower peak oxygen uptake (P = .037), impaired walking economy (P = .021), and higher fractional utilization while walking (P = 0.019) than patients without metabolic syndrome.

Table II. Treadmill measurements of peripheral arterial disease patients with and without metabolic syndrome
VariablesControl group⁎ (n = 201)Metabolic syndrome group⁎ (n = 133)P†
ICD (meters)180±166128±121.018
ACD (meters)409±255319±195.025
Peak oxygen uptake‡14.8±3.913.5±3.1.037
Walking economy‡11.1±2.311.8±2.6.021
Fractional utilization (%)75±1887±17.019

ICD, Initial claudication distance; ACD, absolute claudication distance.

⁎ Values are means ± SD.

† Adjusted for body mass index.

‡ Measured as mL · kg−1 · min−1.

As summarized in Table III, patients with metabolic syndrome also had shorter 6-minute walk pain-free (P = .031) and total (P = .027) distances, lower WIQ distance (P = .010), speed (P = .002), and stair climbing (P = .002) scores, lower self-perceived health (P < .001), and a lower summary performance score (P < .001) than the control group. Patients with metabolic syndrome also had lower health-related quality of life (Table IV) for the domains of physical function (P = .029), role limitations due to physical problems (P = .044), bodily pain (P = .026), general health (P < .001), role limitations due to emotional problems (P = .034), and vitality (P = .011).

Table III. Physical function, self-reported health, and physical activity level of peripheral arterial disease patients with and without metabolic syndrome
VariablesControl group⁎ (n = 201)Metabolic syndrome group⁎ (n = 133)P†
6-minute walk test
Pain-free distance (meters)198±139167±116.031
Walk distance (meters)381±103338±95.027
WIQ
Distance score (%)38±3530±33.010
Speed score (%)39±3028±25.002
Stair-climbing score (%)45±3533±32.002
Summary performance score (units)10.8±2.29.9±1.9<.001
Self-perceived health (%)76±1762±19<.001
Physical activity scale (units)1.5±1.11.2±1.0.375
Daily physical activity (kcal/day)345±204320±196.369

WIQ, Walking Impairment Questionnaire.

⁎ Values are means ± SD.

† Adjusted for body mass index.

Table IV. Health-related quality-of-life measurements of peripheral arterial disease patients with and without metabolic syndrome
VariablesControl group⁎ (n = 201)Metabolic syndrome group⁎ (n = 133)P†
Physical function58±2346±24.029
Role limitations—physical60±4241±42.044
Bodily pain62±2348±21.026
General health65±2047±22<.001
Social function82±2273±27.072
Role limitations—emotional75±3754±41.034
Mental health77±1676±18.844
Vitality63±2050±19.011

⁎ Values are means ± SD.

† Adjusted for body mass index.

The peripheral hemodynamic measurements of the patients with and without metabolic syndrome are listed n Table V. After vascular occlusion, the increase in calf blood flow was impaired in patients with metabolic syndrome (P = .028), and the reduction in calf TcPo2 was greater (P < .001). The ischemic response to arterial occlusion was associated with physical function measures of the patients with metabolic syndrome. The change in calf TcPo2 after vascular occlusion was correlated with ICD (r = 0.30, P = .004), ACD (r = 0.40, P < .001), peak oxygen uptake (r = 0.52, P < .001), walking economy (r = −0.54, P < .001), and fractional utilization (r = −0.53, P < .001). The change in calf blood flow after vascular occlusion was not significantly correlated with the physical function measures of the patients with metabolic syndrome.

Table V. Peripheral hemodynamic measurements of peripheral arterial disease patients with and without metabolic syndrome
VariablesControl group⁎ (n = 201)Metabolic syndrome group⁎ (n = 133)P†
Calf blood flow
Rest (%/min)3.50±1.823.66±1.57.134
Hyperemia (%/min)9.97±4.638.85±4.42.290
Change from rest to hyperemia (%)185±137142±131.028
Calf TcPo2
Rest (mm Hg)38±1837±17.639
Hyperemia (mm Hg)27±2020±18.203
Change from rest to hyperemia (%)−29±22−46±23<.001

TcPo2, transcutaneous oxygen tension.

⁎ Values are means ± SD.

† Adjusted for body mass index.

Back to Article Outline

Discussion 

The major findings of this investigation were that (1) patients limited by intermittent claudication who had metabolic syndrome had shorter claudication distances, lower cardiopulmonary function, impaired ambulatory function, lower health-related quality of life, and diminished peripheral circulation than patients without metabolic syndrome, and (2) calf ischemia in those with metabolic syndrome was predictive of intermittent claudication and physical function.

Metabolic syndrome exacerbates the ambulatory dysfunction of PAD patients limited by intermittent claudication. During the graded treadmill test, patients with metabolic syndrome experienced ICD and ACD sooner than those without metabolic syndrome. To our knowledge, this is the first investigation examining the effect of metabolic syndrome on ambulation in PAD patients limited by intermittent claudication.

In a previous report,34 BMI was a significant predictor of ICD and ACD, as higher BMI values were associated with more rapid development of intermittent claudication. The current study adjusted for BMI, suggesting that the shorter ICD and ACD of patients with metabolic syndrome was not merely related to the added burden of walking in patients having greater body mass.35 Rather, the clustering of risk factors that comprise the metabolic syndrome negatively impact intermittent claudication in patients with PAD.

The earlier and more rapid development of leg symptoms associated with metabolic syndrome leads to impaired cardiopulmonary measures such as peak oxygen uptake, walking economy, and fractional utilization of oxygen during ambulation. The lower peak oxygen uptake of PAD patients with metabolic syndrome supports a previous observation that metabolic syndrome impairs cardiorespiratory fitness in adult men and women.36 Furthermore, the higher values of walking economy and fractional utilization in patients with metabolic syndrome are clinically relevant because they reflect less efficient ambulation and more intense exercise while walking at a given pace. Consequently, PAD patients with metabolic syndrome may have difficulty completing activities of daily living requiring relatively high intensities.

The more rapid rate of claudication pain in patients with metabolic syndrome was even evident during the less intensive 6-minute walk test, resulting in lower self-perceived ability to ambulate at varying distances and speeds and to climb stairs. The impairments in ambulation in patients with metabolic syndrome resulted in lower self-perceived health and lower health-related quality-of-life scores on all domains except for mental health and social functioning.

Metabolic syndrome diminishes the peripheral circulation of PAD patients limited by intermittent claudication. Patients with metabolic syndrome had greater calf ischemia and lower calf blood flow in response to vascular occlusion than those without metabolic syndrome. The ischemic response to vascular occlusion was related to ambulatory function in PAD patients with metabolic syndrome, whereas the hyperemic response was not. Thus, the change in transcutaneous oxygen tension after vascular occlusion is one factor associated with the development of ischemic claudication pain and may be a sensitive marker of vascular reactivity in PAD patients.37 In addition to worsening claudication pain, the greater peripheral ischemia in patients with metabolic syndrome is related to greater impairments in cardiopulmonary function and to greater ambulatory dysfunction during a constant, submaximal treadmill test.

The clinical relevance of this study is that PAD patients who are limited by intermittent claudication and who have metabolic syndrome have greater ambulatory dysfunction and may be at greater risk for subsequent mobility loss28 than patients who do not have metabolic syndrome. Interventions designed to treat the risk factors of metabolic syndrome are needed to determine efficacy in treating intermittent claudication and improve the long-term prognosis of PAD patients limited by intermittent claudication. Thus, future intervention trials are needed to extend the preliminary findings of the current study that metabolic syndrome negatively impacts ambulation in functionally limited PAD patients.

Back to Article Outline

Conclusion 

Metabolic syndrome worsens intermittent claudication, physical function, health-related quality of life, and peripheral circulation in patients with PAD; and calf ischemia in those with metabolic syndrome was predictive of intermittent claudication and physical function. Thus, the additive burden of metabolic syndrome places patients who are limited by intermittent claudication at an even greater risk for living a functionally dependent lifestyle. Aggressive risk-factor modification designed to treat components of metabolic syndrome should be evaluated for efficacy in modifying physical and vascular function in patients with intermittent claudication.

Back to Article Outline

Author contributions 

Conception and design: AWG, PSM

Analysis and interpretation: AWG, DEP

Data collection: AWG, PSM

Writing the article: AWG

Critical revision of the article: AWG, PSM, DEP

Final approval of the article: AWG, PSM, DEP

Statistical analysis: AWG, DEP

Obtained funding: AWG

Overall responsibility: AWG

Back to Article Outline

References 

  1. Criqui MH , Langer RD , Fronek A , Feigelson HS , Klauber MR , McCann TJ , et al.   Mortality over a period of 10 years in patients with peripheral arterial disease . N Engl J Med . 1992;326:381–386
  2. Howell MA , Colgan MP , Seeger RW , Ramsey DE , Sumner DS . Relationship of severity of lower limb peripheral vascular disease to mortality and morbidity (a six-year follow-up study) . J Vasc Surg . 1989;9:691–697
  3. McDermott MM , Feinglass J , Slavensky R , Pearce WH . The ankle-brachial index as a predictor of survival in patients with peripheral vascular disease . J Gen Intern Med . 1994;9:445–449
  4. McKenna M , Wolfson S , Kuller L . The ratio of ankle and arm arterial pressure as an independent predictor of mortality . Atherosclerosis . 1991;87:119–128
  5. Vogt MT , Cauley JA , Newman AB , Kuller LH , Hulley SB . Decreased ankle/arm blood pressure index and mortality in elderly women . JAMA . 1993;270:465–469
  6. Vogt MT , McKenna M , Anderson SJ , Wolfson SK , Kuller LH . The relationship between ankle-arm index and mortality in older men and women . J Am Geriatr Soc . 1993;41:523–530
  7. Vogt MT , Wolfson SK , Kuller LH . Segmental arterial disease in the lower extremities (correlates of disease and relationship to mortality) . J Clin Epidemiol . 1993;46:1267–1276
  8. Vogt MT , Wolfson SK , Kuller LH . Lower extremity arterial disease and the aging process (a review) . J Clin Epidemiol . 1992;45:529–542
  9. Weitz JI , Byrne J , Clagett GP , Farkouh ME , Porter JM , Sackett DL , et al.   Diagnosis and treatment of chronic arterial insufficiency of the lower extremities (a critical review) . Circulation . 1996;94:3026–3049
  10. Bonde-Petersen F . The effects of varying walking speeds when measuring the claudication distance on horizontal and sloping levels . Acta Chir Scand . 1967;133:627–630
  11. Gardner AW . Claudication pain and hemodynamic responses to exercise in younger and older peripheral arterial disease patients . J Gerontol A Biol Sci Med Sci . 1993;48:M231–M236
  12. Gardner AW , Ricci MR , Case TD , Pilcher DB . Practical equations to predict claudication pain distances from a graded treadmill test . Vasc Med . 1996;1:91–96
  13. Hiatt WR , Nawaz D , Regensteiner JG , Hossack KF . The evaluation of exercise performance in patients with peripheral vascular disease . J Cardiopulmonary Rehabil . 1988;12:525–532
  14. Sieminski DJ , Gardner AW . The relationship between free-living daily physical activity and the severity of peripheral arterial occlusive disease . Vasc Med . 1997;2:286–291
  15. Feinglass J , McCarthy WJ , Slavensky R , Manheim LM , Martin GJ  the Chicago Claudication Outcomes Research Group . Effect of lower extremity blood pressure on physical functioning in patients who have intermittent claudication . J Vasc Surg . 1996;24:503–512
  16. Sieminski DJ , Cowell LL , Montgomery PS , Pillai SB , Gardner AW . Physical activity monitoring in peripheral arterial occlusive disease patients . J Cardiopulmonary Rehabil . 1997;17:43–47
  17. Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults . Executive summary of the third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) . JAMA . 2001;285:2486–2497
  18. Dekker JM , Girman C , Rhodes T , Nijpels G , Stehouwer CDA , Bouter LM , et al.   Metabolic syndrome and 10-year cardiovascular disease risk in the Hoorn Study . Circulation . 2005;112:666–673
  19. Pentecost MJ , Criqui MH , Dorros G , Goldstone J , Johnston KW , Martin EC , et al.   Guidelines for peripheral percutaneous transluminal angioplasty of the abdominal aorta and lower extremity vessels . Circulation . 1994;89:511–531
  20. Gardner AW , Skinner JS , Cantwell BW , Smith LK . Progressive vs single-stage treadmill tests for evaluation of claudication . Med Sci Sports Exerc . 1991;23:402–408
  21. Ford ES , Giles WH , Dietz WH . Prevalence of metabolic syndrome among US adults . JAMA . 2002;287:356–359
  22. Gardner AW , Killewich LA , Katzel LI , Womack CJ , Montgomery PS , Otis RB , et al.   Relationship between free-living daily physical activity and peripheral circulation in patients with intermittent claudication . Angiology . 1999;50:289–297
  23. Gardner AW . Reliability of transcutaneous oximeter electrode power during exercise in patients with intermittent claudication . Angiology . 1997;48:229–235
  24. Womack CJ , Sieminski DJ , Katzel LI , Yataco A , Gardner AW . Improved walking economy in patients with peripheral arterial occlusive disease . Med Sci Sports Exerc . 1997;29:1286–1290
  25. Montgomery PS , Gardner AW . The clinical utility of a 6-minute walk test in peripheral arterial occlusive disease patients . J Am Geriatr Soc . 1998;46:706–711
  26. Regensteiner JG , Steiner JF , Panzer RL , Hiatt WR . Evaluation of walking impairment by questionnaire in patients with peripheral arterial disease . J Vasc Med Biol . 1990;2:142–152
  27. Guralnik JM , Simonsick EM , Ferrucci L , Glynn RJ , Berkman LF , Blazer DG , et al.   A short physical performance battery assessing lower extremity function (association with self-reported disability and prediction of mortality and nursing home admission) . J Gerontol A Biol Sci Med Sci . 1994;49:M85–M94
  28. Guralnik JM , Ferrucci L , Simonsick EM , Salive ME , Wallace RB . Lower extremity function in persons over the age of 70 years as a predictor of subsequent disability . N Engl J Med . 1995;332:556–561
  29. Gardner AW , Montgomery PS , Killewich LA . Natural history of physical function in patients with intermittent claudication . J Vasc Surg . 2004;40:73–78
  30. Bartman BA , Rosen MJ , Bradham DD , Weissman J , Hochberg M , Revicki DA . Relationship between health status and utility measures in older claudicants . Qual Life Res . 1998;7:67–73
  31. Gardner AW , Poehlman ET . Assessment of free-living daily physical activity in older claudicants (Validation against the doubly labeled water technique) . J Gerontol A Biol Sci Med Sci . 1998;53A:M275–M280
  32. Ware JE , Sherbourne CD . The MOS 36-item short-form health survey (SF-36) . Med Care . 1992;30:473–483
  33. Gardner AW , Sieminski DJ , Killewich LA . The effect of cigarette smoking on free-living daily physical activity in older claudication patients . Angiology . 1997;48:947–955
  34. Gardner AW , Ricci MA , Case TD , Pilcher DB . Practical equations to predict claudication pain distances from a graded treadmill test . Vasc Med . 1996;1:91–96
  35. Wyatt MG , Scott PMJ , Scott DJA , Poskett K , Baird RN , Horrocks M . Effect of weight on claudication distance . Br J Surg . 1991;78:1386–1388
  36. Whaley MH , Kampert JB , Kohl HW , Blair SN . Physical fitness and clustering of risk factors associated with the metabolic syndrome . Med Sci Sports Exerc . 1999;31:287–293
  37. Frau G . Transcutaneous PO2 response to transient arterial occlusion in peripheral vascular disease detected by heating power oximeter . Angiology . 2001;52:851–857

 Andrew W. Gardner, PhD, was supported by grants from the National Institute on Aging (NIA) (R01-AG-16685, K01-00657), by a Claude D. Pepper Older American Independence Center grant from NIA (P60-AG12583), by a Geriatric, Research, Education, and Clinical Center grant (GRECC) from the Veterans Affairs administration, and by a National Institutes of Health, National Center for Research Resources, General Clinical Research Center grant (M01-RR-14467).Competition of interest: none.CME article

PII: S0741-5214(06)00390-9

doi:10.1016/j.jvs.2006.02.042

Journal of Vascular Surgery
Volume 43, Issue 6 , Pages 1191-1196, June 2006

Article Tools