Association of insulin resistance and inflammation with peripheral arterial disease: the National Health and Nutrition Examination Survey, 1999 to 2004

Effects of dialysis on peripheral arterial disease

End-stage renal disease is an independent risk factor for the development of peripheral arterial disease, with considerably worse outcomes in patients with concomitant diseases. It is important to realize the widespread, yet frequently asymptomatic, nature of peripheral arterial disease in patients with end-stage renal disease due to the presence of other comorbidities that decrease activity levels and sensation to allow for early recognition and timely medical management to try and mitigate otherwise poor outcomes. Despite their high risk, properly selected patients derive benefit from revascularization; both open and endovascular approaches provide similar outcomes in terms of overall survival, amputation-free survival, and limb salvage, with perhaps a slight preference toward open repair. This narrative review of the literature evaluates the epidemiology, pathophysiology, outcomes, and management strategies that provide the best possible outcomes for patients with peripheral arterial disease and end-stage renal disease.

Interaction and combined effect of triglyceride-glucose index and hypertension on type 2 diabetes individuals' peripheral arterial disease risk

BACKGROUND

The interaction and combined effect of the triglyceride-glucose (TyG) index, an alternative parameter of insulin resistance, along with hypertension (HT), on the risk of peripheral arterial disease (PAD), a specific type of atherosclerotic cardiovascular disease, in individuals with type 2 diabetes (T2D) seems straightforward. However, specific research on this topic remains scarce.

METHODS

In this cross-sectional study, 2027 adult participants with T2D were devided into four groups based on the mean values of TyG index and various blood pressure parameters along with its category. Binary logistic regression, interaction analysis, combined effect size, and goodness-of-fit of the constructed models were performed.

RESULTS

The TyG index's individual effect and it's combined effect with HT, or higher systolic blood pressure (SBP) or higher mean arterial pressure in patients with T2D correlated with a higher PAD risk respectively (odds ratio [OR], 0.50, [95% confidence interval {CI} 0.28-0.89]; OR, 0.32, [95% CI 0.12-0.90]; OR, 0.35, [95% CI 0.13-0.94]; OR, 0.35, [95% CI 0.12-0.98], respectively). Only an interaction effect exists between the TyG index and SBP (multiplicative interaction{INTM}: 1.02 [1.002, 1.038]). Combining them can significantly improve the accuracy of predicting PAD (area under the receiver operating characteristic curve {AUC}MAX = 0.7, AUCModel3 + TyG index + SBP-AUCModel3 = 0.027). All P values were < 0.05.

CONCLUSION

This study suggested that TyG index and hypertension, as well as their combined and interaction effect were significantly correlated with the risk of PAD in T2D individuals.

Investigating the association between the triglyceride-glucose index and peripheral artery disease: a systematic review and meta-analysis

BACKGROUND

Peripheral artery disease (PAD) is a common disease associated with atherosclerosis, leading to significant mortality and morbidity worldwide. Our study focuses on the association between insulin resistance (IR) and PAD, specifically investigating the triglyceride-glucose index (TyG) as a potential surrogate marker of IR in the context of PAD by pooling the existing studies on this topic.

METHODS

Online databases, including PubMed, Embase, Scopus, and the Web of Science, were searched to find the studies comparing the TyG index in PAD vs. control, reporting the TyG index among PAD severities, and assessing the association of increase in TyG with PAD prevalence. Random-effect meta-analysis was performed to calculate the standardized mean difference (SMD) and 95% confidence interval (CI) for TyG level comparison and to calculate pooled odds ratio (ORs) for a 1-unit increase in TyG and higher vs. lower quartile/tertile of TyG association with PAD.

RESULTS

In the final review, 22 studies comprising 73,168 cases were included. Random-effect meta-analysis showed that patients with PAD had significantly higher levels of the TyG index compared with controls (SMD 0.76, 95%CI 0.65-0.88, P < 0.001). Also, higher severities of PAD were associated with higher TyG levels (SMD 0.48, 95%CI 0.22-0.74, P = 0.0003). Additionally, a 1-unit increase in TyG was associated with a 60% increase in odds of PAD (OR 1.60, 95%CI 1.41-1.80, P < 0.001). Finally, the highest quartile (Q4) of TyG had significantly higher odds of PAD compared to Q1 (OR 1.94, 95%CI 1.49-2.54, P < 0.001).

CONCLUSION

Our meta-analysis has identified a significant association between TyG levels and PAD and its severity. These findings not only contribute to our understanding of the role of IR in PAD pathology but also offer clinicians an exact index for evaluating PAD risk and its complications. This could potentially lead to more effective prevention and management strategies in the future.

Cardiovascular Effectiveness and Safety of Antidiabetic Drugs in Patients with Type 2 Diabetes and Peripheral Artery Disease: Systematic Review

Peripheral artery disease (PAD) is an atherosclerotic condition commonly complicating type 2 diabetes (T2D), leading to poor quality of life and increased risk of major adverse lower-limb (MALE) and cardiovascular (CV) events (MACE). Therapeutic management of PAD in T2D patients is much more arduous, often due to bilateral, multi-vessel, and distal vascular involvement, in addition to increased systemic polyvascular atherosclerotic burden. On the other hand, the pathophysiological link between PAD and T2D is very complex, involving mechanisms such as endothelial dysfunction and increased subclinical inflammation in addition to chronic hyperglycemia. Therefore, the clinical approach should not ignore vascular protection with the aim of reducing limb and overall CV events besides a mere glucose-lowering effect. However, the choice of the best medications in this setting is challenging due to low-grade evidence or lacking targeted studies in PAD patients. The present review highlighted the strong relationship between T2D and PAD, focusing on the best treatment strategy to reduce CV risk and prevent PAD occurrence and worsening in patients with T2D. The Medline databases were searched for studies including T2D and PAD up to June 2024 and reporting the CV effectiveness and safety of the most used glucose-lowering agents, with no restriction on PAD definition, study design, or country. The main outcomes considered were MACE-including nonfatal acute myocardial infarction, nonfatal stroke, and CV death-and MALE-defined as lower-limb complications, amputations, or need for revascularization. To the best of our current knowledge, GLP-1 receptor agonists and SGLT2 inhibitors represent the best choice to reduce CV risk in T2D and PAD settings, but a personalized approach should be considered. GLP-1 receptor agonists should be preferred in subjects with prevalent atherosclerotic burden and a history of previous MALE, while SGLT2 inhibitors should be used in those with heart failure if overall CV benefits outweigh the risk of lower-limb complications.

Relationship between peripheral arterial disease severity determined by the Glass classification and triglyceride-glucose index; novel association and novel classification system

Peripheral arterial disease is a serious clinical manifestation caused by atherosclerosis. It is one common cause of morbidity and mortality worldwide. It is commonly seen in males, and its (prevelance) increases with age. It is most prevalent with smoking, hypertension, diabetes mellitus and hyperlip-idemia. Novel studies investigate the relationship between triglyceride-glucose index (TyG) and cardiovascular diseases. Studies investigating the association of this index and peripheral arterial disease and disease severity are generally done by using The Trans-Atlantic Inter-Society Consensus (TASC) classification. We aimed to study this association by using the new Global Limb Anatomic Staging System (GLASS) classification. Two hundred patients between 25 to 90 years old diagnosed with peripheral arterial disease and admitted to the hospital for peripheral arterial angiography between July 2021 and December 2021, were evaluated retrospectively with blood parameters and angiographic images. Patients were divided into two groups: moderate (group 1; n=58) and severe (group 2; n=142) according to the GLASS classification. No statistical differences were observed for comorbidities and repeated interventional pro-cedure rates (p=0.164). Triglyceride values were found to be statistically dif-ferent between groups (p=0.040). TyG was found higher in group 2 (p= 0.04). According to the binary logistic regression model, only TyG was found to have a significant effect as a diagnostic factor (p=0.011). TyG was also significantly correlated with the Rutherford (p=0.012) and GLASS classification severity (p<0.001). Peripheral arterial disease and disease severity could be easily moni-tored with simple calculable TyG. In this way, precautions could be taken, and morbidities could be prevented.

Triglyceride-glucose index in the development of peripheral artery disease: findings from the Atherosclerosis Risk in Communities (ARIC) Study

Background

It remains unclear whether triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, is prospectively associated with incident peripheral arterial disease (PAD).

Methods

We included 12,320 Atherosclerosis Risk in Communities Study participants (aged 54.3 ± 5.7 years) free of a history of PAD at baseline (visit 1: 1987–1989). The TyG index was determined using ln (fasting triglycerides [mg/dL] × fasting glucose [mg/dL]/2), and measured at 5 visits between 1987 and 2013. Incident PAD was defined as the first hospitalization with PAD diagnosis or a new onset of measured ABI < 0.90 during follow-up visits. We quantified the association of both baseline and trajectories of TyG index with incident PAD using Cox regression and logistic regression analysis, respectively.

Results

Over a median follow-up of 23 years, 1300 participants developed PAD. After adjustment for traditional PAD risk factors, each 1-SD (0.58) increase in TyG index was associated with an 11.9% higher risk of incident PAD [hazard ratio, 1.119 (95% CI, 1.049–1.195)]. Results were similar when individuals were categorized by TyG index quartiles [hazard ratio, 1.239 (95% CI, 1.028–1.492); comparing extreme quartiles]. Four distinct trajectories of stable TyG indexes at various levels along the follow-up duration were identified [low (22.2%), moderate (43.2%), high (27.5%), and very high (7.1%) trajectory groups]. Compared with those with a TyG index trajectory at a low level, those participants with TyG index trajectories at high and very high levels had an even greater risk of future incident PAD [odds ratio (95%CI): 1.404 (1.132–1.740) and 1.742 (1.294–2.344), respectively] after multivariate adjustments for traditional PAD risk factors.

Conclusions

Higher TyG index is independently associated with an increased risk of incident PAD. Long-term trajectories of TyG index help identify individuals at a higher risk of PAD who deserve specific preventive and therapeutic approaches.

Trial registration: Clinical trial registration number: The ARIC trial was registered at clinicaltrials.gov as NCT00005131.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01319-1.

AST/ALT Ratio and Peripheral Artery Disease in a Chinese Hypertensive Population: A Cross-Sectional Study

Previous studies reported that the aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio (AST/ALT) was a risk factor in cardiovascular disease. Peripheral artery disease (PAD) is an important risk factor for cardiovascular death. However, only a few studies investigated the correlations between the AST/ALT ratio and PAD. We analyzed data from 10 900 patients with hypertension from the Chinese Hypertension Registry Study; 350 patients had PAD (prevalence 3.2%). After adjusting for potential confounders, the AST/ALT ratio was independently and positively associated with risk of PAD (OR: 1.31, 95% CI, 1.13-1.59), and a significant increased risk of PAD for the third AST/ALT ratio tertile (T3) compared with the first tertile (T1; OR: 1.49, 95% CI, 1.09-2.04, P _trend = .005) was found. Moreover, when we combined T1 and T2 into one group and used it as a reference group, the risk of PAD increased with the increase in AST/ALT; the risk ratio was 1.52 (95% CI, 1.20-1.95). A higher AST/ALT ratio (≥1.65) was associated with PAD risk in Chinese adults with hypertension. Our results suggest that the AST/ALT ratio may help identify patients at high risk of vascular end points and might be a convenient, economical, and effective tool for evaluating the risk of atherosclerosis.

Skeletal muscle expression of adipose-specific phospholipase in peripheral artery disease

Flow-limiting atherosclerotic lesions of arteries supplying the limbs are a cause of symptoms in patients with peripheral artery disease (PAD). Musculoskeletal metabolic factors also contribute to the pathophysiology of claudication, which is manifest as leg discomfort that impairs walking capacity. Accordingly, we conducted a case-control study to determine whether skeletal muscle metabolic gene expression is altered in PAD. Calf skeletal muscle gene expression of patients with PAD and healthy subjects was analyzed using microarrays. The top-ranking gene differentially expressed between PAD and controls (FDR < 0.001) was PLA2G16, which encodes adipose-specific phospholipase A2 (AdPLA) and is implicated in the maintenance of insulin sensitivity and regulation of lipid metabolism. Differential expression was confirmed by qRT-PCR; PLA2G16 was downregulated by 68% in patients with PAD (p < 0.001). Expression of Pla2g16 was then measured in control (db/+) and diabetic (db/db) mice that underwent unilateral femoral artery ligation. There was significantly reduced expression of Pla2g16 in the ischemic leg of both control and diabetic mice (by 51%), with significantly greater magnitude of reduction in the diabetic mice (by 79%). We conclude that AdPLA is downregulated in humans with PAD and in mice with hindlimb ischemia. Reduced AdPLA may contribute to impaired walking capacity in patients with PAD via its effects on skeletal muscle metabolism. Further studies are needed to fully characterize the role of AdPLA in PAD and to investigate its potential as a therapeutic target for alleviating symptoms of claudication.

Coronary and peripheral artery plaques: do differences in plaque characteristics translate to differences in lipid management?

Optimal medical management of patients with peripheral arterial disease (PAD) includes statin therapy, which has been shown to decrease the risk of major cardiovascular events. However, the relationship between low-density lipoprotein (LDL) lowering, PAD progression and limb outcomes remains controversial. Although prevention of coronary and cerebrovascular events is a priority, limb outcomes are still important determinants of quality of life and healthcare spending. This review will highlight differences between coronary artery disease (CAD) and PAD, and in particular, the more prevalent role of lipids and LDL cholesterol in CAD versus calcification in PAD. This difference may contribute to the differential impact of LDL cholesterol levels on coronary events and outcomes versus limb outcomes. Beyond LDL lowering, immune modulators have emerged as another agent to treat atherosclerosis in CAD, however similar data in PAD are lacking. Small studies have suggested that other lipids besides LDL cholesterol, such as triglycerides or small dense LDL, may have a greater impact on limb outcomes in patients with PAD. Although statin therapy is central in the management of patients with PAD, current understanding of the distinctions between PAD and CAD suggest that there may be other non-LDL targets for risk reduction that require further study.

Associations between Triglyceride-Glucose Index and Micro- and Macro-angiopathies in Type 2 Diabetes Mellitus

The aim of this study was to investigate the associations between the triglyceride-glucose (TyG) index, a marker of insulin resistance, and microangiopathies and macroangiopathies in patients with type 2 diabetes mellitus (DM). Our study enrolled 1990 type 2 diabetic patients from local hospitals in Taiwan during the period of 2002–2004. Multivariate logistic regression analysis was used to identify the factors related to microangiopathies, macroangiopathiess and TyG index. The patients were stratified by TyG index quartile (Q1–Q4). Adjusted odds ratios (aORs) of albuminuria for Q3 versus Q1 and Q4 versus Q1 were 1.424 (95% confidence interval [CI], 1.062–1.910, p = 0.018) and 1.948 (95% CI, 1.437–2.642, p < 0.001), respectively. The aOR of cerebrovascular disease (CVA) was 2.264 for Q4 versus Q1 (95% CI, 1.243–4.122, p = 0.008), but there were no significant associations with diabetic retinopathy (DR), coronary artery disease (CAD) or peripheral artery occlusive disease (PAOD). Significant stepwise increases were found in CVA (p = 0.0013) and albuminuria ≥30 mg/g (p < 0.001) corresponding to TyG index quartiles, but not DR (p = 0.573), CAD (p = 0.880) or PAOD (p = 0.223). There was a significant association between a high TyG index and a high risk of microalbuminuria and CVA in the study cohort. Further studies to investigate the use of medications in patients with DM to prevent micro- and macro-angiopathies are thus warranted.

Twenty-Year Predictors of Peripheral Arterial Disease Compared With Coronary Heart Disease in the Scottish Heart Health Extended Cohort (SHHEC)

BACKGROUND

Coronary heart disease and peripheral arterial disease (PAD) affect different vascular territories. Supplementing baseline findings with assays from stored serum, we compared their 20-year predictors.

METHODS AND RESULTS

We randomly recruited 15 737 disease-free men and women aged 30 to 75 years across Scotland between 1984 and 1995 and followed them through 2009 for death and hospital diagnoses. Of these, 3098 developed coronary heart disease (19.7%), and 499 PAD (3.2%). Hazard ratios for 45 variables in the Cox model were adjusted for age and sex and for factors in the 2007 ASSIGN cardiovascular risk score. Forty-four of them were entered into parsimonious predictive models, tested by c-statistics and net reclassification improvements. Many hazard ratios diminished with adjustment and parsimonious modeling, leaving significant survivors. The hazard ratios were mostly higher in PAD. New parsimonious models increased the c-statistic and net reclassification improvements over ASSIGN variables alone but varied in their components and ranking. Coronary heart disease and PAD shared 7 of the 9 factors from ASSIGN: age, sex, family history, socioeconomic status, diabetes mellitus, tobacco smoking, and systolic blood pressure (but neither total nor high-density lipoprotein cholesterol); plus 4 new ones: NT-pro-BNP, cotinine, high-sensitivity C-reactive protein, and cystatin-C. The highest ranked hazard ratios for continuous factors in coronary heart disease were those for age, total cholesterol, high-sensitivity troponin, NT-pro-BNP, cotinine, apolipoprotein A, and waist circumference (plus 10 more); in PAD they were age, high-sensitivity C-reactive protein, systolic blood pressure, expired carbon monoxide, cotinine, socioeconomic status, and lipoprotein (a) (plus 5 more).

CONCLUSIONS

The mixture of shared with disparate determinants for arterial disease in the heart and the legs implies nonidentical pathogenesis: cholesterol dominant in the former, and inflammation (high-sensitivity C-reactive protein, diabetes mellitus, smoking) in the latter.

Risk Factors for Mortality Among Individuals With Peripheral Arterial Disease

Morbidity and mortality from peripheral arterial disease (PAD) continues to increase. Traditional cardiovascular risk factors are implicated in the development of PAD, yet the extent to which those risk factors correlate with mortality in such patients remains insufficiently assessed. Using data from the 1999 to 2004 National Health and Nutrition Examination Survey, Cox proportional hazards models were used to examine the association of cardiovascular risk factors and all-cause and cardiovascular mortality. A total of 647 individuals ≥40 years old with PAD (i.e., ankle-brachial index [ABI] ≤ 0.9) were followed for a median of 7.8 years. There were 336 deaths, of which 98 were attributable to cardiovascular disease. Compared with never smokers, current (hazard ratio [HR] 2.45, 95% confidence interval [CI] 1.62 to 3.71) and former (HR 1.62, 95% CI 1.14 to 2.29) smokers with PAD had higher rates of death. Moderate or vigorous physical activity of ≥10 minutes monthly was associated with lower death rates (HR 0.63, 95% CI 0.44 to 0.91). Also associated with increased rates of cardiovascular death were an ABI of <0.5 (HR 2.56, 95% CI 1.28 to 5.15, compared with those with an ABI of 0.7 to 0.9) and diabetes mellitus (HR 2.50, 95% CI 1.33 to 4.73). Neither C-reactive protein nor body mass index was associated with mortality. In conclusion, tobacco use increased the risk of all-cause and cardiovascular death, whereas physical activity was associated with a decreased mortality risk. A low ABI and diabetes were also predictive of cardiovascular death.

Deletion of TXNIP Mitigates High-Fat Diet-Impaired Angiogenesis and Prevents Inflammation in a Mouse Model of Critical Limb Ischemia

Background: Previous work demonstrated that high-fat diet (HFD) triggered thioredoxin-interacting protein (TXNIP) and that silencing TXNIP prevents diabetes-impaired vascular recovery. Here, we examine the impact of genetic deletion of TXNIP on HFD-impaired vascular recovery using hind limb ischemia model. Methods: Wild type mice (WT, C57Bl/6) and TXNIP knockout mice (TKO) were fed either normal chow diet (WT-ND and TKO-ND) or 60% high-fat diet (WT-HFD and TKO-HFD). After four weeks of HFD, unilateral hind limb ischemia was performed and blood flow was measured using Laser doppler scanner at baseline and then weekly for an additional three weeks. Vascular density, nitrative stress, infiltration of CD68+ macrophages, and expression of inflammasome, vascular endothelial growth factor (VEGF), VEGF receptor-2 were examined by slot blot, Western blot and immunohistochemistry. Results: By week 8, HFD caused similar increases in weight, cholesterol and triglycerides in both WT and TKO. At week 4 and week 8, HFD significantly impaired glucose tolerance in WT and to a lesser extent in TKO. HFD significantly impaired blood flow and vascular density (CD31 labeled) in skeletal muscle of WT mice compared to ND but not in TKO. HFD and ischemia significantly induced tyrosine nitration, and systemic IL-1β and infiltration of CD68+ cells in skeletal muscle from WT but not from TKO. HFD significantly increased cleaved-caspase-1 and IL-1 β compared to ND. Under both ND, ischemia tended to increase VEGF expression and increased VEGFR2 activation in WT only but not TKO. Conclusion: Similar to prior observation in diabetes, HFD-induced obesity can compromise vascular recovery in response to ischemic insult. The mechanism involves increased TXNIP-NLRP3 (nucleotide-binding oligomerization domain-like receptor protein 3) inflammasome activation, nitrative stress and impaired VEGFR2 activation. Deletion of TXNIP restored blood flow, reduced nitrative stress and blunted inflammasome-mediated inflammation; however, it did not impact VEGF/VEGFR2 in HFD. Targeting TXNIP-NLRP3 inflammasome can provide potential therapeutic target in obesity-induced vascular complication.

Incidence of Peripheral Arterial Disease and Its Association with Pulse Pressure: A Prospective Cohort Study

BACKGROUND

The association of pulse pressure and peripheral arterial disease (PAD) has seldom been examined using a prospective design. This study aimed to investigate the association of pulse pressure with PAD incidence in an elderly general population.

METHODS

We utilized data from a cohort conducted in Beijing with additionally 2-year follow-up time. PAD was defined as an ankle brachial index value <0.9 in either leg. Cox proportional hazard regression model was used to quantify the magnitude of pulse pressure on PAD incidence.

RESULTS

During a 2-year follow-up time, 357 of 4,201 (8.5%) participants developed PAD with 105 (6.9%) men and 252 (9.4%) women, respectively. After adjusting for baseline age, sex, body mass index, hypertension, diabetes, total cholesterol, and high-density lipoprotein cholesterol, and smoking, the hazard ratio and 95% confidence interval for people with pulse pressure greater than 60 mmHg was 2.20 (1.53, 3.15) compared with those whose pulse pressure was less than 40 mmHg. A linear trend was observed for the association of pulse pressure with PAD.

CONCLUSION

Higher pulse pressure was associated with higher PAD incidence.

Independent Factors of Changes of Ankle-Brachial Index in Peripheral Arterial Occlusive Disease in Elderly Patients with or without Diabetes

Peripheral arterial disease (PAD) belongs to the commonly-occurring pathologies associated with elderly age. A simple tool for defining the severity of PAD is the ankle-brachial index (ABI). The purpose of this research was to determine independent factors of changes of ABI in elderly patients with occlusive PAD disease (PAOD) with and without diabetes. The research was carried out on 49 elderly patients with PAOD, including 29 patients with type 2 diabetes, and 20 patients without diabetes. The concentration of interleukin-6 (IL-6), E-selectin, fibrinogen, and C-reactive protein (CRP) in the blood serum was marked. In all patients, the independent factors of changes of ABI were determined with the use of the multiple logistic regression analysis. Our results show that in the group of patients with PAOD suffering from diabetes, it was demonstrated that the ABI was related to age, the duration of the symptoms of PAD, body mass index (BMI), low-density lipoprotein cholesterol, fibrinogen, and sex (determination coefficient R² = 0.699). In patients with PAOD without diabetes, the ABI was related to age, the duration of the symptoms of PAD, the levels of CRP, E-selectin, high-density lipoprotein cholesterol, and the glomerular filtration rate(determination coefficient R² = 0.844). We conclude that in elderly patients with PAOD with and without diabetes, the participation of independent factors related to the ABI is diversified; in patients with diabetes, the concentration of IL-6 and fibrinogen is lower, and the concentration of E-selectin is higher than in patients without diabetes.

Socioeconomic inequality and peripheral artery disease prevalence in US adults

BACKGROUND

Lower socioeconomic status is associated with cardiovascular disease. We sought to determine whether there is a higher prevalence of peripheral artery disease (PAD) in individuals with lower socioeconomic status.

METHODS AND RESULTS

We analyzed data from the National Health and Nutrition Examination Survey 1999 to 2004. PAD was defined based on an ankle.brachial index .0.90. Measures of socioeconomic status included poverty.income ratio,a ratio of self-reported income relative to the poverty line, and attained education level. Of 6791 eligible participants,overall weighted prevalence of PAD was 5.8% (SE, 0.3). PAD prevalence was significantly higher in individuals with low income and lower education. Individuals in the lowest of the 6 poverty.income ratio categories had more than a2-fold increased odds of PAD compared with those in the highest poverty-income ratio category (odds ratio, 2.69; 95%confidence interval, 1.80.4.03; P<0.0001). This association remained significant even after multivariable adjustment(odds ratio, 1.64; 95% confidence interval, 1.04.2.6; P=0.034). Lower attained education level also associated with higher PAD prevalence (odds ratio, 2.8; 95% confidence interval, 1.96.4.0; P<0.0001) but was no longer significant after multivariable adjustment.

CONCLUSIONS

Low income and lower attained education level are associated with PAD in US adults. These data suggest that individuals of lower socioeconomic status remain at high risk and highlight the need for education and advocacy efforts focused on these at-risk populations.

Inflammatory biomarkers in peripheral arterial disease

Biochemical markers have the potential to aid the vascular specialist in many ways. On a daily basis, we rely on such markers as d-dimer to help exclude thromboembolic disease and thus limit low-probability ultrasound imaging. Additionally, we use troponin levels to determine myocardial events perioperatively. During the past decade, use of the inflammatory marker C-reactive protein has been recommended by the American Heart Association to further stratify patient cardiovascular risk, and has been studied more extensively in patients with peripheral vascular disease. This review details clinical information published during the past several decades on the application of serum C-reactive protein levels in peripheral arterial disease patients in correlation with disease severity and likelihood of future cardiovascular events, including recent predictive models.

Effects of aldosterone on insulin sensitivity and secretion

Dr. Conn originally reported an increased risk of diabetes in patients with hyperaldosteronism in the 1950s, although the mechanism remains unclear. Aldosterone-induced hypokalemia was initially described to impair glucose tolerance by impairing insulin secretion. Correction of hypokalemia by potassium supplementation only partially restored insulin secretion and glucose tolerance, however. Aldosterone also impairs glucose-stimulated insulin secretion in isolated pancreatic islets via reactive oxygen species in a mineralocorticoid receptor-independent manner. Aldosterone-induced mineralocorticoid receptor activation also impairs insulin sensitivity in adipocytes and skeletal muscle. Aldosterone may produce insulin resistance secondarily by altering potassium, increasing inflammatory cytokines, and reducing beneficial adipokines such as adiponectin. Renin-angiotensin system antagonists reduce circulating aldosterone concentrations and also the risk of type 2 diabetes in clinical trials. These data suggest that primary and secondary hyperaldosteronism may contribute to worsening glucose tolerance by impairing insulin sensitivity or insulin secretion in humans. Future studies should define the effects of MR antagonists and aldosterone on insulin secretion and sensitivity in humans.

Association of monocyte tumor necrosis factor α expression and serum inflammatory biomarkers with walking impairment in peripheral artery disease

OBJECTIVE

Inflammation contributes to the development of peripheral artery disease (PAD) and may contribute to intermittent claudication by adversely affecting vascular and skeletal muscle function. We explored the association of inflammation to maximal walking time (MWT) in patients with claudication.

METHODS

Circulating inflammatory biomarkers, including tumor necrosis factor α (TNF-α), C-reactive protein (CRP), interleukin-6 (IL-6), and soluble intercellular adhesion molecule 1 (sICAM), were measured in 75 subjects with intermittent claudication as well as in 43 healthy subjects. Real-time polymerase chain reaction was used to quantify mRNA expression of TNF-α, IL-6, interferon-γ, and CD36 from peripheral blood monocytes. Treadmill testing was performed in PAD subjects to assess MWT.

RESULTS

Compared with healthy subjects, PAD subjects had higher levels of circulating TNF-α (P < .0001), CRP (P = .003), sICAM (P < .0001), and IL-6 (P < .0001). Expression of both IL-6 (P = .024) and CD36 (P = .018) was greater in PAD subjects than in healthy subjects. Among subjects with PAD, higher gene expression of TNF-α was associated inversely with MWT (P = .01). MWT was also associated inversely with greater levels of circulating TNF-α (P = .028), CRP (P = .024), IL-6 (P = .03), and sICAM (P = .018).

CONCLUSIONS

Systemic inflammation, as indicated by TNF-α inflammatory gene expression in peripheral blood monocytes and by circulating biomarker levels, is associated with impairment in walking time in patients with PAD and intermittent claudication.

Pulse pressure and subclinical peripheral artery disease

Ankle-brachial index (ABI) measurement offers an easily available method to diagnose peripheral artery disease (PAD) and systemic atherosclerosis in early stage and thus to identify high-risk individuals for preventive interventions. The objective of this study was to assess the most practical criteria for the measurement of ABI in subjects with high cardiovascular risk. We examined 972 asymptomatic, middle-aged high-risk subjects without manifested cardiovascular disease or previously diagnosed diabetes. The prevalence of PAD (defined as ABI0.90) and borderline PAD (0.91-1.00) were 5% (95% confidence interval (CI) 4-7%) (49/972) and 20% (95% CI 18-23%) (192/972), respectively. In multivariate analysis, female gender (odds ratio (OR) 0.71 (95% CI 0.53-0.97)), current smoking (OR 2.14 (95% CI 1.47-3.11)) and pulse pressure (OR 1.03 for each increase of 1 mm Hg (95% CI 1.01-1.04)) were associated with low ABI. Measuring ABI in subjects who smoke or have pulse pressure >65 mm Hg seems to be worthwhile.

n-3 Polyunsaturated fatty acids supplementation in peripheral artery disease: the OMEGA-PAD trial

Despite current consensus guidelines recommending intensive cardiovascular risk factor management for peripheral artery disease (PAD), patients suffering from PAD continue to experience significant morbidity and mortality. This excess morbid burden is at least partially related to impaired vascular function and systemic inflammation. Interventions bridging this gap are critical. Dietary supplementation of n-3 polyunsaturated fatty acids (n-3 PUFA) has been shown to improve endothelial function and reduce inflammation in different cohorts, as well as to decrease cardiovascular events in secondary prevention trials in patients with coronary artery disease. Their effects in the PAD population are, however, less well understood. The OMEGA-PAD trial is a double-blinded, randomized, placebo-controlled trial that examines the impact of a high-dose, short-duration dietary oral supplementation of n-3 PUFA on vascular function and inflammation in patients with established PAD. The purpose of this article is to provide a detailed description of the design and methods of the OMEGA-PAD trial, and a summary of baseline characteristics of the cohort.

Insulin status and vascular responses to weight loss in obesity

OBJECTIVES

The aim of this study was to determine whether the effects of weight loss on arterial function are differentially modified by insulin status.

BACKGROUND

Clinical studies suggest that plasma insulin levels may predict the extent of cardiovascular benefit achieved with weight loss in obese individuals, but mechanisms are currently unknown.

METHODS

We prospectively followed 208 overweight or obese patients (body mass index [BMI] ≥25 kg/m(2)) receiving medical/dietary (48%) or bariatric surgical (52%) weight-loss treatment during a median period of 11.7 months (interquartile range: 4.6 to 13 months). We measured plasma metabolic parameters and vascular endothelial function using ultrasound at baseline and following weight-loss intervention and stratified analyses by median plasma insulin levels.

RESULTS

Patients age 45 ± 1 years, with BMI 45 ± 9 kg/m(2), experienced 14 ± 14% weight loss during the study period. In individuals with higher baseline plasma insulin levels (above median >12 μIU/ml; n = 99), ≥10% weight loss (compared with <10%) significantly improved brachial artery macrovascular flow-mediated vasodilation and microvascular reactive hyperemia (p < 0.05 for all). By contrast, vascular function did not change significantly in the lower insulin group (≤12 μIU/ml; n = 109) despite a similar degree of weight loss. In analyses using a 5% weight loss cut point, only microvascular responses improved in the higher insulin group (p = 0.02).

CONCLUSIONS

Insulin status is an important determinant of the positive effect of weight reduction on vascular function with hyperinsulinemic patients deriving the greatest benefit. Integrated improvement in both microvascular and macrovascular function was associated with ≥10% weight loss. Reversal of insulin resistance and endothelial dysfunction may represent key therapeutic targets for cardiovascular risk reduction in obesity.

Insulin resistance is significantly associated with the metabolic syndrome, but not with sonographically proven peripheral arterial disease

Objective

Insulin resistance (IR) is the key feature of the metabolic syndrome (MetS); its association with peripheral arterial disease (PAD) is unclear. We hypothesized that IR is associated with both the MetS and sonographically proven PAD.

Methods

IR was determined by the Homeostasis Model Assessment (HOMA) index in 214 patients with sonographically proven PAD as well as in 197 controls, who did not have a history of PAD and in whom coronary artery disease was ruled out angiographically; the MetS was defined according to NCEP-ATPIII criteria.

Results

HOMA IR scores were significantly higher in MetS patients than in subjects without the MetS (5.9 ± 6.2 vs. 2.9 ± 3.9; p <0.001). However, HOMA IR did not differ significantly between patients with PAD and controls (4.2 ± 5.4 vs. 3.3 ± 4.3; p = 0.124). When both, the presence of MetS and of PAD were considered, HOMA IR was significantly higher in patients with the MetS both among those with PAD (6.1 ± 5.7 vs. 3.6 ± 5.2; p<0.001) and among controls (5.8 ± 6.8 vs. 2.3 ± 1.8; p <0.001), whereas it did not differ significantly between patients with PAD and controls among patients with the MetS (5.8 ± 6.8 vs. 6.1 ± 5.7; p = 0.587) nor among those without the MetS (2.3 ± 1.8 vs. 3.6 ± 5.2; p = 0.165). Similar results were obtained with the International Diabetes Federation definition of the MetS.

Conclusion

IR is significantly associated with the MetS but not with sonographically proven PAD.

Inflammatory biomarkers for predicting cardiovascular disease

The pathology of cardiovascular disease (CVD) is complex; multiple biological pathways have been implicated, including, but not limited to, inflammation and oxidative stress. Biomarkers of inflammation and oxidative stress may serve to help identify patients at risk for CVD, to monitor the efficacy of treatments, and to develop new pharmacological tools. However, due to the complexities of CVD pathogenesis there is no single biomarker available to estimate absolute risk of future cardiovascular events. Furthermore, not all biomarkers are equal; the functions of many biomarkers overlap, some offer better prognostic information than others, and some are better suited to identify/predict the pathogenesis of particular cardiovascular events. The identification of the most appropriate set of biomarkers can provide a detailed picture of the specific nature of the cardiovascular event. The following review provides an overview of existing and emerging inflammatory biomarkers, pro-inflammatory cytokines, anti-inflammatory cytokines, chemokines, oxidative stress biomarkers, and antioxidant biomarkers. The functions of each biomarker are discussed, and prognostic data are provided where available.

Treatment with beta-blockers is associated with lower levels of Lp-PLA2 and suPAR in carotid plaques

OBJECTIVES

To determine whether a long-term treatment with beta-blockers influences the inflammatory activity in carotid artery disease by reducing the carotid plaque levels of lipoprotein-associated phospholipase A2 (Lp-PLA2), its enzymatic products lysophosphatidylcholine (lysoPCs), and of soluble urokinase plasminogen activator receptor (suPAR).

MATERIALS AND METHODS

One hundred and thirty-four patients with significant symptomatic or asymptomatic carotid stenosis undergoing surgery were prospectively included and divided into two groups (Group A or B) based on the absence or presence of an on-going long-term oral treatment with beta-blockers. The harvested carotid plaques were analyzed for the levels of lysoPCs using mass spectrometry and Lp-PLA2 and suPAR by Enzyme-linked immunosorbent assay (ELISA).

RESULTS

Plaques of patients on long-term treatment with beta-blockers revealed lower levels of Lp-PLA2 (Group A 0.752 ± 0.393 ug/g vs. Group B 0.644 ± 0.445 ug/g, P=.049) as well as suPAR (Group A 0.044 ± 0.024 μg/g vs. Group B 0.036 ± 0.025 μg/g, P=.028). Levels of Lp-PLA2 and suPAR were positively correlated (r=.637, P<.0001). Lp-PLA2 and suPAR levels were also correlated (P<.0001) with the three lysoPC species tested (lysoPC 16:0, lysoPC 18:0. lysoPC 18:1). All the above-mentioned findings were confirmed after correction for age, gender, hypertension, coronary artery disease, and statin usage.

CONCLUSIONS

The reduced levels of Lp-PLA2 and suPAR in human carotid plaques of subjects on long-term treatment with beta-blockers suggest their possible protective role in plaque inflammation. Our findings support an even more selective Lp-PLA2 and suPAR inhibition as a possible strategy for the prevention of cardiovascular disease.

Long-term effects of beraprost sodium on arteriosclerosis obliterans: a single-center retrospective study of Japanese patients

INTRODUCTION

Arteriosclerosis obliterans (ASO) causes ischemic symptoms of the lower limbs, reducing quality of life (QOL), and has a poor prognosis. Early diagnosis and treatment are necessary. In this study, the effects of long-term administration of beraprost sodium (beraprost) to treat ASO were investigated.

METHODS

One hundred and eighty eight patients treated with beraprost for ≥1 year were retrospectively identified. Outcomes were lower limb ischemic symptoms, carotid intima/media thickness (IMT), and cardiovascular events. Patients reported visual analog scale scores for major symptoms at baseline and after 3, 6, and 12 months of treatment.

RESULTS

Overall, 188 patients (mean age 70.8 ± 10.15 years, Fontaine classification: grade I 14.4%, grade II 85.6%) treated with beraprost for 2.4-10.7 years (mean 6.5 years) were included in this study. Administration of beraprost significantly reduced patient-reported severity of lower limb ischemic symptoms in all patients at 12 months, including those with diabetes, hypertension, or dyslipidemia. IMT decreased from 1.09 ± 0.09 mm at baseline to 1.04 ± 0.11 mm at 12 months (P < 0.001). Decreases in IMT were similar in patients with diabetes, hypertension, or dyslipidemia. Overall, 26 (13.8%) events occurred during a mean follow-up of 6.5 years, including 23 cardiovascular events (unstable angina in three patients, myocardial infarction in six patients, cerebral infarction in eight patients, and transient cerebral ischemic attack in six patients) and non-cardiovascular death in three patients. Beraprost at 120 μg/day significantly reduced the risk of ischemic symptoms compared with <120 μg/day (adjusted hazard ratio: 0.17; 95% confidence interval: 0.06, 0.45; P < 0.001). No severe adverse events or adverse events requiring dose reductions/discontinuation occurred during long-term administration of beraprost.

CONCLUSION

Beraprost reduced lower limb ischemic symptoms, IMT, and the incidence of cardiovascular events in patients with ASO.

Insulin Sensitivity and Beta-Cell Function Are Associated with Arterial Stiffness in Individuals without Hypertension

Aim. We investigated the relationship between brachial-ankle pulse wave velocity (baPWV) and glucose levels, insulin sensitivity, and beta-cell function in Chinese individuals with or without hypertension. Methods. We recruited 3137 nondiabetic individuals whose age, body mass index (BMI), glucose levels, blood pressure (BP), lipids, hemoglobin A1C (HbA1c), baPWV, and insulin levels were measured. Results. In normotensive group, 2 h glucose levels (β = 0.046, P < 0.001) associated with baPWV, showed a significant increase in patients with NG as compared to those with DM (P = 0.032). The hypertensive group showed no such differences. The Matsuda index (β = 0.114, P < 0.001) and HOMA- β (β = 0.045, P < 0.001) were negatively correlated with baPWV while lnHOMA-IR (β = 0.196, P = 0.076) and the Quantitative Insulin Sensitivity Check Index (QUICKI) (β = 0.226, P = 0.046) showed a borderline negative correlation. BaPWV significantly decreased (P = 0.032) with an increase in insulin sensitivity in individuals with both normal BP and glucose tolerance. Conclusions. BaPWV was significantly associated with 2 h glucose levels, insulin sensitivity and beta-cell function in normotensive population, whereas in hypertensive individuals, BP was the dominant factor influencing arterial stiffness. Individuals with abnormal insulin sensitivity in the absence of diabetes and hypertension are also at an increased risk of arterial stiffness.

Role of adipose and hepatic atypical protein kinase C lambda (PKCλ) in the development of obesity and glucose intolerance

PKCλ, an atypical member of the multifunctional protein kinase C family, has been implicated in the regulation of insulin-stimulated glucose transport and of the intracellular immune response. To further elucidate the role of this cellular regulator in diet-induced obesity and insulin resistance, we generated both liver (PKC-Alb) and adipose tissue (PKC-Ap2) specific knockout mice. Body weight, fat mass, food intake, glucose homeostasis and energy expenditure were evaluated in mice maintained on either chow or high fat diet (HFD). Ablation of PKCλ from the adipose tissue resulted in mice that were indistinguishable from their wild-type littermates. However, PKC-Alb mice were resistant to diet-induced obesity (DIO). Surprisingly this DIO resistance was not associated with either a reduction in caloric intake or an increase in energy expenditure as compared with their wild-type littermates. Furthermore, these mice displayed an improvement in glucose tolerance. When maintained on chow diet, these mice were similar to wild types in respect to body weight and fat mass, yet insulin sensitivity was impaired compared with wt littermates. Taken together these data suggest that hepatic PKCλ is modulating insulin-mediated glucose turnover and response to high fat diet feeding, thus offering a deeper understanding of an important target for anti-obesity therapeutics.

High-sensitivity C-reactive protein and ankle brachial index in a finnish cardiovascular risk population

High-sensitivity C-reactive protein (hsCRP) has been previously linked to different forms of vascular disease. However, some studies have not found any relationship between hsCRP and atherosclerosis. Also, studies investigating correlation between hsCRP and ankle brachial index (ABI) are scarce. We studied hsCRP in a cardiovascular risk population with a special interest in correlation between hsCRP and ABI. All men and women aged 45 to 70 years from a rural town Harjavalta, Finland were invited to participate in a population survey. Diabetics and people with known vascular disease were excluded. Seventy-three percent (n = 2085) of the invited persons participated and 70% of the respondents (n = 1496) had at least one risk factor to cardiovascular diseases. These subjects were invited to further examinations. From them we measured ABI, hsCRP, leukocyte count, glucose tolerance, systemic coronary risk evaluation (SCORE), body mass index (BMI), and waist circumference. Mean hsCRP was 1.9 mg/L. Smokers had higher hsCRP (mean 2.2 mg/L) than nonsmokers (mean 1.8 mL/L). hsCRP in women was higher than in men (mean 2.0 mg/L versus 1.8 mg/L). Mean ABI was 1.10, and the prevalence of peripheral arterial disease was 3.1%. ABI correlated weakly with hsCRP (r = -0.077, p = 0.014), leukocyte count (r = -0.107, p = 0.001), and SCORE (r = -0.116, p = 0.001). It did not have correlation between age, weight, BMI, or waist circumference. hsCRP correlated with BMI (r = 0.208, p < 0.0001) and waist circumference (r = 0.325, p < 0.0001). When we excluded subjects with hsCRP >10 mg/L, ABI no longer correlated with hsCRP. In a cardiovascular risk population, hsCRP has only a weak correlation with ABI, and this correlation disappeared when we excluded subject with hsCRP >10 mg/L. Instead, hsCRP was correlated to the measures of obesity (waist circumference and BMI), indicating its role as a marker of adipose tissue-driven inflammation. hsCRP does not seem to be a suitable screening method for peripheral arterial disease.

Treatment strategy for type 2 diabetes from the perspective of systemic vascular protection and insulin resistance

This paper provides an update on the mechanisms of vascular impairment associated with insulin resistance and the pathogenesis of diabetic nephropathy and peripheral artery disease (PAD). It also considers the optimal treatment strategies for systemic vascular protection in light of recent findings. This area is of major clinical importance given the ongoing global epidemic of type 2 diabetes and the pivotal role played by insulin resistance in the mechanism of vascular impairment that manifests as macroangiopathy and microangiopathy. Timely diagnosis and intervention is critical in patients with systemic arteriosclerotic disease. Therefore, treatment strategies are aimed not only at targeting the presenting pathology, but also at reducing the risk of cardiovascular events. These efforts can help reduce the risk of both cardiovascular events and mortality. Treatment for PAD includes pharmacotherapy, endovascular treatment, and vascular reconstruction, along with exercise therapy. Because PAD can cause ischemia in the lower extremities, typical drug approaches include use of vasodilators and antiplatelet agents. Beraprost sodium and cilostazol are common choices in Japan, and their risks and benefits are discussed. Of note, beraprost has several therapeutic properties, including vascular endothelial protection, and antiplatelet and anti-inflammatory effects, in addition to vasodilatory activity. In patients with PAD, these activities improve the pathological process in the lower extremities and reduce the incidence of systemic vascular events. Recent preclinical findings indicate that beraprost improves not only ischemic extremities through its vasodilatory properties, but also reduces the insulin resistance which affects vascular endothelium. In this way, beraprost may contribute to an overall systemic vascular protective action. The use of agents, such as beraprost, which are capable of improving insulin resistance and resulting vascular endothelial function at an earlier disease stage, may ultimately contribute to increasing the life expectancy of patients with PAD.

Risk factors for peripheral arterial disease among patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have an increased risk for developing peripheral arterial disease (PAD). The aim of this study was to examine the cross-sectional association between novel risk factors and prevalent PAD in patients with CKD. A total of 3,758 patients with estimated glomerular filtration rates of 20 to 70 ml/min/1.73 m(2) who participated in the Chronic Renal Insufficiency Cohort (CRIC) study were included in the present analysis. PAD was defined as an ankle-brachial index <0.9 or a history of arm or leg revascularization. After adjustment for age, gender, race, cigarette smoking, physical activity, history of hypertension and diabetes, pulse pressure, high-density lipoprotein cholesterol, estimated glomerular filtration rate, and CRIC clinical sites, several novel risk factors were significantly associated with PAD. For example, odds ratios for a 1-SD higher level of risk factors were 1.18 (95% confidence interval [CI] 1.08 to 1.29) for log-transformed high-sensitivity C-reactive protein, 1.18 (95% CI 1.08 to 1.29) for white blood cell count, 1.15 (95% CI 1.05 to 1.25) for fibrinogen, 1.13 (95% CI 1.03 to 1.24) for uric acid, 1.14 (95% CI 1.02 to 1.26) for glycosylated hemoglobin, 1.11 (95% CI 1.00 to 1.23) for log-transformed homeostasis model assessment of insulin resistance, and 1.35 (95% CI 1.18 to 1.55) for cystatin C. In conclusion, these data indicate that inflammation, prothrombotic state, oxidative stress, insulin resistance, and cystatin C were associated with an increased prevalence of PAD in patients with CKD. Further studies are warranted to examine the causal effect of these risk factors on PAD in patients with CKD.

Red cell distribution width and risk of peripheral artery disease: Analysis of National Health and Nutrition Examination Survey 1999–2004

Red cell distribution width (RDW) is an independent predictor of the 10-year estimated risk of coronary heart disease (CHD) events. However, RDW’s association with peripheral artery disease (PAD) – a CHD risk equivalent – has not been evaluated to date. In this cross-sectional study, we examined 6950 participants of the National Health and Nutrition Examination Survey, 1999–2004. PAD was defined as an ankle–brachial index below 0.9 ( n = 618). RDW was divided into quartiles (Q) (Q1: ≤ 12.2; Q2: 12.3–12.5; Q3: 12.6–13.0; Q4: ≥ 13.1) and PAD risk was compared across these quartiles using adjusted multivariate logistic regression. A graded increase in prevalent PAD with increasing RDW quartiles was observed (4.2% in Q1 vs 13.9% in Q4; test of trend p < 0.001). Risk of PAD was significantly higher (odds ratio (OR) 1.19, 95% confidence interval (CI): 1.06–1.34; p = 0.003) after adjusting for age, sex, race, body mass index, hypertension, hyperlipidemia, diabetes, smoking, estimated glomerular filtration rate, C-reactive protein, hemoglobin, mean corpuscular volume, and nutritional factors (folate, iron and vitamin B12) deficiencies with each unit (0.1) increase in RDW. Upon receiver-operating characteristics analysis, the predictive accuracy of the American College of Cardiology / American Heart Association (ACC/AHA)-defined PAD screening criteria (for a high-risk population) was 0.657 at best, but improved significantly (0.727) after addition of RDW ( p < 0.0001). In conclusion, higher levels of RDW are independently associated with a higher risk of PAD and can significantly improve the risk prediction beyond that estimated by ACC/AHA-defined PAD screening criteria.

Insulin resistance and incident peripheral artery disease in the Cardiovascular Health Study

Type 2 diabetes is a risk factor for peripheral artery disease (PAD), and insulin resistance is a key feature of diabetes and pre-diabetes. No longitudinal epidemiological study has examined the relation between insulin resistance and PAD. Our study analyzed the association of quartiles of the homeostatic model of insulin resistance (HOMA-IR) and the development of PAD defined by two methods. PAD was first defined as the development of an abnormal ankle-brachial index (ABI) (dichotomous outcome) after 6 years of follow-up. PAD was alternatively defined as the development of clinical PAD (time-to-event analysis). The study samples included adults over the age of 65 years who were enrolled in the Cardiovascular Health Study, had fasting measurements of insulin and glucose, had ABI measurements, and were not receiving treatment for diabetes. Multivariable models were adjusted for potential confounders, including age, sex, field center and cohort, body mass index (BMI), smoking status, alcohol use, and exercise intensity. Additional models adjusted for potential mediators, including blood pressure, lipids, kidney function, and prevalent vascular disease. In the ABI analysis (n = 2108), multivariable adjusted models demonstrated a positive relation between HOMA-IR and incident PAD (odds ratio = 1.80 comparing the 4th versus 1st quartile of HOMA-IR, 95% confidence interval [CI] 1.20-2.71). In the clinical PAD analysis (n = 4208), we found a similar relation (hazard ratio = 2.30 comparing the 4th versus 1st quartile of HOMA-IR, 95% CI 1.15-4.58). As expected, further adjustment for potential mediators led to some attenuation of effect estimates. In conclusion, insulin resistance is associated with a higher risk of PAD in older adults.

Insulin resistance and arterial stiffness in healthy adolescents and young adults

AIMS/HYPOTHESIS

Increased arterial stiffness is a risk factor for adverse cardiovascular events in adults with obesity-related insulin resistance (IR) or type 2 diabetes mellitus. Adolescents with type 2 diabetes have stiffer vessels. Whether stiffness is increased in obesity/IR in youth is not known. We sought to determine if IR was a determinant of arterial stiffness in youth, independent of obesity and cardiovascular risk factors.

METHODS

We measured cardiovascular risk factors, IR, adipocytokines and arterial stiffness (brachial artery distensibility [BrachD], pulse wave velocity [PWV]) and wave reflection (augmentation index [AIx]) in 343 adolescents and young adults without type 2 diabetes (15-28 years old, 47% male, 48% non-white). Individuals <85th percentile of BMI were classified as lean (n = 232). Obese individuals were grouped by HOMA index as not insulin resistant (n = 46) or insulin resistant (n = 65) by the 90th percentile for HOMA for lean. Mean differences were evaluated by ANOVA. Multivariate models evaluated whether HOMA was an independent determinant of arterial stiffness.

RESULTS

Risk factors deteriorated from lean to obese to obese/insulin resistant (all p ≤ 0.017). Higher AIx, lower BrachD and higher PWV indicated increased arterial stiffness in obese and obese/insulin-resistant participants. HOMA was not an independent determinant. Age, sex, BMI and BP were the most consistent determinants, with HDL-cholesterol playing a role for BrachD and leptin for PWV (AIx R²= 0.34; BrachD R² = 0.37; PWV R² = 0.40; all p ≤ 0.02).

CONCLUSIONS/INTERPRETATION

Although IR is associated with increased arterial stiffness, traditional cardiovascular risk factors, especially obesity and BP, are the major determinants of arterial stiffness in healthy young people.

Clinical subtypes of depression are associated with specific metabolic parameters and circadian endocrine profiles in women: the power study

BACKGROUND

Major depressive disorder (MDD) has been associated with adverse medical consequences, including cardiovascular disease and osteoporosis. Patients with MDD may be classified as having melancholic, atypical, or undifferentiated features. The goal of the present study was to assess whether these clinical subtypes of depression have different endocrine and metabolic features and consequently, varying medical outcomes.

METHODS

Premenopausal women, ages 21 to 45 years, with MDD (N = 89) and healthy controls (N = 44) were recruited for a prospective study of bone turnover. Women with MDD were classified as having melancholic (N = 51), atypical (N = 16), or undifferentiated (N = 22) features. Outcome measures included: metabolic parameters, body composition, bone mineral density (BMD), and 24 hourly sampling of plasma adrenocorticotropin (ACTH), cortisol, and leptin.

RESULTS

Compared with control subjects, women with undifferentiated and atypical features of MDD exhibited greater BMI, waist/hip ratio, and whole body and abdominal fat mass. Women with undifferentiated MDD characteristics also had higher lipid and fasting glucose levels in addition to a greater prevalence of low BMD at the femoral neck compared to controls. Elevated ACTH levels were demonstrated in women with atypical features of depression, whereas higher mean 24-hour leptin levels were observed in the melancholic subgroup.

CONCLUSIONS

Pre-menopausal women with various features of MDD exhibit metabolic, endocrine, and BMD features that may be associated with different health consequences.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00006180.

Secondary prevention and mortality in peripheral artery disease: National Health and Nutrition Examination Study, 1999 to 2004

BACKGROUND

Whether individuals with peripheral artery disease (PAD) identified by screening ankle-brachial index benefit from preventive therapies to reduce cardiovascular risk is unknown. We aimed to determine the number of US adults with PAD who are not receiving preventive therapies and whether treatment is associated with reduced mortality in PAD subjects without known cardiovascular disease.

METHODS AND RESULTS

We analyzed data from the National Health and Nutrition Examination Survey (NHANES) 1999 to 2004 with mortality follow-up through December 31, 2006. We defined PAD as an ankle-brachial index ≤0.90. Of 7458 eligible participants ≥40 years, weighted PAD prevalence was 5.9±0.3% (mean±SE), corresponding to ≈7.1 million US adults with PAD. Statin use was reported in only 30.5±2.5%, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use in 24.9±1.9%, and aspirin use in 35.8±2.9%, corresponding to 5.0 million adults with PAD not taking statins, 5.4 million not taking angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, and 4.5 million not receiving aspirin. After adjustment for age, sex, and race/ethnicity, PAD was associated with all-cause mortality (hazard ratio, 2.4; 95% confidence interval, 1.9 to 2.9; P<0.0001). Even after exclusion of individuals with known cardiovascular disease, subjects with PAD had higher mortality rates (16.1±2.1%) than subjects without PAD or cardiovascular disease (4.1±0.3%), with an adjusted hazard ratio of 1.9 (95% confidence interval, 1.3 to 2.8; P=0.001). Among PAD subjects without cardiovascular disease, use of multiple preventive therapies was associated with 65% lower all-cause mortality (hazard ratio, 0.35; 95% confidence interval, 0.20 to 0.86; P=0.02).

CONCLUSIONS

Millions of US adults with PAD are not receiving secondary prevention therapies. Treatment with multiple therapies is associated with reduced all-cause mortality.

Peripheral artery disease. Part 1: clinical evaluation and noninvasive diagnosis

Peripheral artery disease (PAD) is a marker of systemic atherosclerosis. Most patients with PAD also have concomitant coronary artery disease (CAD), and a large burden of morbidity and mortality in patients with PAD is related to myocardial infarction, ischemic stroke, and cardiovascular death. PAD patients without clinical evidence of CAD have the same relative risk of death from cardiac or cerebrovascular causes as those diagnosed with prior CAD, consistent with the systemic nature of the disease. The same risk factors that contribute to CAD and cerebrovascular disease also lead to the development of PAD. Because of the high prevalence of asymptomatic disease and because only a small percentage of PAD patients present with classic claudication, PAD is frequently underdiagnosed and thus undertreated. Health care providers may have difficulty differentiating PAD from other diseases affecting the limb, such as arthritis, spinal stenosis or venous disease. In Part 1 of this Review, we explain the epidemiology of and risk factors for PAD, and discuss the clinical presentation and diagnostic evaluation of patients with this condition.