Risk factors associated with the development of peripheral arterial disease in smokers: a case-control study

Endothelial injury and decline in lung function in persons living with HIV: a prospective Danish cohort study including 698 adults

Objectives

Endothelial injury may promote declining lung function. We aimed to investigate in well-treated persons living with HIV (PLWH) whether elevated levels of thrombomodulin (TM) and syndecan-1 (SDC1) are associated with excess lung function decline and worsening dyspnea.

Methods

A prospective cohort study comprising patients from the Copenhagen municipality. We included 698 PLWH with undetectable viral load. Biomarkers and demographics were measured at baseline, spirometry [forced expiratory volume in one second (FEV1) and forced vital capacity (FVC)] and dyspnea score both at baseline and 2-year follow-up.Both biomarkers were dichotomized at the 3rd quartile. Decline in lung function was estimated using a linear mixed model with patient-specific random effect. Increase in dyspnea score was estimated using a general mixed logistic regression model.

Results

We did not find an association between elevated SDC1 or TM and an excess decline in neither FEV1: SDC1: 4.5 mL/year (95% CI: -3.9-12.9, p = 0.30), TM: 2.2 mL/year (95% CI: -6.0-10.4, p = 0.60) nor FVC: SDC1: 4.1 mL/year (95% CI: -6.0-14.2, p = 0.42), TM: 1.4 mL/year (95% CI: -8.3-11.1, p = 0.78). A subgroup analysis of never-smokers was consistent with the main analysis.Likewise, we did not find any association between elevated SDC1 and TM and increase in dyspnea score: SDC1: OR 1.43 (95% CI: 0.89-2.30, p = 0.14), TM: OR 1.05 (95% CI: 0.65-1.71, p = 0.26).

Conclusion

We did not find a significant association between elevated biomarkers of endothelial injury and decline in lung function nor dyspnea.

Lower Extremity Peripheral Artery Disease: Contemporary Epidemiology, Management Gaps, and Future Directions: A Scientific Statement From the American Heart Association

Lower extremity peripheral artery disease (PAD) affects >230 million adults worldwide and is associated with increased risk of various adverse clinical outcomes (other cardiovascular diseases such as coronary heart disease and stroke and leg outcomes such as amputation). Despite its prevalence and clinical importance, PAD has been historically underappreciated by health care professionals and patients. This underappreciation seems multifactorial (eg, limited availability of the first-line diagnostic test, the ankle-brachial index, in clinics; incorrect perceptions that a leg vascular disease is not fatal and that the diagnosis of PAD would not necessarily change clinical practice). In the past several years, a body of evidence has indicated that these perceptions are incorrect. Several studies have consistently demonstrated that many patients with PAD are not receiving evidence-based therapies. Thus, this scientific statement provides an update for health care professionals regarding contemporary epidemiology (eg, prevalence, temporal trends, risk factors, and complications) of PAD, the present status of diagnosis (physiological tests and imaging modalities), and the major gaps in the management of PAD (eg, medications, exercise therapy, and revascularization). The statement also lists key gaps in research, clinical practice, and implementation related to PAD. Orchestrated efforts among different parties (eg, health care providers, researchers, expert organizations, and health care organizations) will be needed to increase the awareness and understanding of PAD and improve the diagnostic approaches, management, and prognosis of PAD.

Screening of peripheral arterial disease in primary health care

Background and purpose

The screening tool for diagnosing lower extremity arterial disease is the assessment of the ankle-brachial index (ABI), which is widely used in general practice. However, resting ABI can easily produce a false negative result. In light of this, our goal was to determine the proportion of definitive diagnoses (peripheral arterial disease [PAD] confirmed or refuted) among patients screened in general practice, and the rate of cases in which the need for further specialized examination is necessary, with special attention to groups having non-compressible arteries and ABI negative symptomatic status. The aim of our work is to improve the efficiency of primary health care screening in PAD and reduce the extremely high domestic amputation ratio.

Patients and methods

Eight hundred and sixteen patients were screened. We used the Edinburgh Questionnaire and recorded medical histories, major risk factors, current complaints, and medication. Physical examinations were performed, including ABI testing.

Results

Thirty-three percent complained about lower extremity claudication; 23% had abnormal ABI values; 13% of the patients within the normal ABI range had complaints of dysbasia; and 12% were in the non-compressible artery group. The ABI-negative symptomatic group’s risk factor profile showed a close similarity to the clear PAD-positive and non-compressible artery groups.

Conclusion

The percentage of PAD could be higher than the number of patients diagnosed by ABI screening. Nearly a quarter of the population fell into the non-compressible artery and ABI-negative symptomatic groups, together defined as the “murky zone”. When screening purposely for PAD, these patients deserve special attention due to the insufficient selectivity and sensitivity of measurements. If there is high clinical suspicion of PAD in spite of normal ABI values, further assessment may be considered.

GWAS of smoking behaviour in 165,436 Japanese people reveals seven new loci and shared genetic architecture

Cigarette smoking is a risk factor for a wide range of human diseases¹. To investigate the genetic components associated with smoking behaviours in the Japanese population, we conducted a genome-wide association study of four smoking-related traits using up to 165,436 individuals. In total, we identified seven new loci, including three loci associated with the number of cigarettes per day (EPHX2-CLU, RET and CUX2-ALDH2), three loci associated with smoking initiation (DLC1, CXCL12-TMEM72-AS1 and GALR1-SALL3) and LINC01793-MIR4432HG, associated with the age of smoking initiation. Of these, three loci (LINC01793-MIR4432HG, CXCL12-TMEM72-AS1 and GALR1-SALL3) were found by conducting an additional sex-stratified genome-wide association study. This additional analysis showed heterogeneity of effects between sexes. The cross-sex linkage disequilibrium score regression^2,3 analysis also indicated that the genetic component of smoking initiation was significantly different between the sexes. Cross-trait linkage disequilibrium score regression analysis and trait-relevant tissue analysis showed that the number of cigarettes per day has a specific genetic background distinct from those of the other three smoking behaviours. We also report 11 diseases that share genetic basis with smoking behaviours. Although the current study should be carefully considered owing to the lack of replication samples, our findings characterized the genetic architecture of smoking behaviours. Further studies in East Asian populations are warranted to confirm our findings.

The association between smoking and the prevalence of intermittent claudication

The objective of this study was to investigate the association between smoking and the prevalence of intermittent claudication (IC). Between 1995 and 1997, all residents aged 20 years or older in Nord-Trøndelag County, Norway, were invited to take part in the Nord-Trøndelag Health Study (Helseundersøkelsen i Nord-Trøndelag: HUNT 2). A total of 19 748 participants aged 40-69 years attended. Responses to 12 questions on IC (including a Norwegian translation of the Edinburgh Claudication Questionnaire) had been previously tested against the ankle-brachial pressure index (ABPI < 0.9), and an algorithm of the best test properties was used to identify people with IC. Using logistic regression analysis we computed age-adjusted prevalence odds ratios (OR) for the association between smoking and IC. Both current (ORmen = 3.8, confidence interval (CI) 2.1-6.7, ORwomen = 2.2, CI 1.4-3.4) and former smokers (ORmen = 1.7, CI 0.9-3.2, ORwomen = 1.7, CI 1.1-2.7) had a higher prevalence of IC compared with those who had never smoked, and individuals who had stopped smoking more than 20 years previously had a substantially lower prevalence of IC (ORmen = 0.2, CI 0.1-0.5, ORwomen = 0.4, CI 0.2-0.8) than current smokers. We found no association between passive smoking and IC in either men or women. Current and previous smoking habits were positively associated with the prevalence of IC, and smoking cessation was negatively associated in men and women. Passive smoking was not associated with IC in this study.

The effect of current cigarette smoking on calf muscle hemoglobin oxygen saturation in patients with intermittent claudication

The purpose of this study was to compare calf muscle hemoglobin oxygen saturation response during exercise between smokers and non-smokers with peripheral arterial disease. Patients limited by intermittent claudication who were smokers (n = 12) were compared with those who had not smoked (n = 28) for at least 1 year prior to investigation. Ankle/brachial index (ABI) measurements were obtained with Doppler ultrasound, and maximal calf blood flow was measured by venous occlusion plethysmography. Hemoglobin oxygen saturation (StO2) of the calf muscle, initial claudication distance (ICD), and absolute claudication distance (ACD) were obtained during a graded treadmill test. Smokers refrained from smoking on the morning of the test. Smokers had similar ABI values compared with non-smokers (0.70 ± 0.26 vs 0.73 ± 0.23 [mean ± SD]; p = 0.808), whereas the smokers had lower values for maximal calf blood flow (8.71 ± 5.76 %/min vs 11.48 ± 4.46 %/min; p = 0.038), ICD (122 ± 123 m vs 243 ± 177 m; p = 0.023), and ACD (284 ± 170 m vs 452 ± 263 m; p = 0.023). Additionally, smokers had lower calf muscle StO2 values at the end of 1 minute (16 ± 15% vs 37 ± 19%; p = 0.002) and 2 minutes of exercise (16 ± 16% vs 35 ± 25%; p = 0.008), and at the occurrence of ICD (17 ± 17% vs 32 ± 23%; p = 0.033) and ACD (16 ± 16% vs 32 ± 24%; p = 0.024). After adjusting for blood flow, calf muscle StO2 values remained lower in the smokers (p < 0.05). Finally, calf muscle StO2 at the end of the first minute of exercise was related to ICD (r = 0.611, p < 0.001) and ACD (r = 0.443, p < 0.01). In conclusion, smokers limited by intermittent claudication have lower calf muscle StO2 during exercise than nonsmokers, and lower StO2 during exercise is associated with shorter ICD and ACD.

Patient Characteristics and Comorbidities Influence Walking Distances in Symptomatic Peripheral Arterial Disease: A Large One-Year Physiotherapy Cohort Study

Objectives

The aim of this study is to investigate the association between age, gender, body-mass index, smoking behavior, orthopedic comorbidity, neurologic comorbidity, cardiac comorbidity, vascular comorbidity, pulmonic comorbidity, internal comorbidity and Initial Claudication Distance during and after Supervised Exercise Therapy at 1, 3, 6 and 12 months in a large sample of patients with Intermittent Claudication.

Methods

Data was prospectively collected in standard physiotherapy care. Patients received Supervised Exercise Therapy according to the guideline Intermittent Claudication of the Royal Dutch Society for Physiotherapy. Three-level mixed linear regression analysis was carried out to analyze the association between patient characteristics, comorbidities and Initial Claudication Distance at 1, 3, 6 and 12 months.

Results

Data from 2995 patients was analyzed. Results showed that being female, advanced age and a high body-mass index were associated with lower Initial Claudication Distance at all-time points (p = 0.000). Besides, a negative association between cardiac comorbidity and Initial Claudication Distance was revealed (p = 0.011). The interaction time by age, time by body-mass index and time by vascular comorbidity were significantly associated with Initial Claudication Distance (p≤ 0.05). Per year increase in age (range: 33–93 years), the reduction in Initial Claudication Distance was 8m after 12 months of Supervised Exercise Therapy. One unit increase in body-mass index (range: 16–44 kg/m²) led to 10m less improvement in Initial Claudication Distance after 12 months and for vascular comorbidity the reduction in improvement was 85m after 12 months.

Conclusions

This study reveals that females, patients at advanced age, patients with a high body-mass index and cardiac comorbidity are more likely to show less improvement in Initial Claudication Distances (ICD) after 1, 3, 6 and 12 months of Supervised Exercise Therapy. Further research should elucidate treatment adaptations that optimize treatment outcomes for these subgroups.

Vasoactive enzymes and blood flow responses to passive and active exercise in peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) is characterised by impaired leg blood flow, which contributes to claudication and reduced exercise capacity. This study investigated to what extent vasoactive enzymes might contribute to altered blood flow in PAD (Fontaine stage II).

METHODS

We compared femoral artery blood flow during reactive hyperaemia, leg-extension exercise and passive leg movement, and determined the level of vasoactive enzymes in skeletal muscle samples from the vastus lateralis in PAD (n = 10, 68.5 ± 6.5 years) and healthy controls (CON, n = 9, 62.1 ± 12.3 years). Leg blood flow was measured with Doppler ultrasound and muscle protein levels of phosphorylated endothelial nitric oxide synthase, NADPH oxidase, cyclooxygenase 1 and 2, thromboxane synthase, and prostacyclin synthase were determined.

RESULTS

Leg blood flow during the initial 90 s of passive leg movement (242 ± 33 vs 441 ± 75 ml min(-1), P = 0.03) and during reactive hyperaemia (423 ± 100 vs 1255 ± 175 ml min(-1), P = 0.002) was lower in PAD than CON, whereas no significant difference was observed for leg blood flow during exercise (1490 ± 250 vs 1887 ± 349 ml min(-1), P = 0.37). PAD had higher NADPH oxidase than CON (1.04 ± 0.19 vs 0.50 ± 0.06 AU, P = 0.02), with no differences for other enzymes. Leg blood flow during exercise was correlated with prostacyclin synthase (P = 0.001).

CONCLUSION

Elevated NADPH oxidase indicates that oxidative stress may be a primary cause of low nitric oxide availability and impaired blood flow in PAD.

[Recent Knowledge of Smoking and Peripheral Arterial Disease in Lower Extremities]

Peripheral arterial disease (PAD) is an atherosclerotic obstructive disease of the arteries in lower extremities. Patients with PAD show high rates of mortality from coronary artery disease (CAD) and stroke. Smoking as well as diabetes is an important risk factor for PAD. A lesion of PAD in the lower extremities tends to be more proximal in smokers than in nonsmokers and to be more distal in patients with diabetes than in nondiabetics. By a systematic review, the odds ratio for PAD of smokers vs nonsmokers has been reported to be in the range of 1.7-7.4. Previous epidemiological studies suggest a stronger association of smoking with PAD than that with CAD. Nitric oxide (NO) is an important molecule suppressing the progression of atherosclerosis, but this function is compromised by smoking. Smoking decreases the bioactivity of NO and the expression level of NO synthase. In addition, smoking results in deteriorations of risk factors for atherosclerosis such as decreases in blood HDL (high-density lipoprotein) cholesterol and tissue plasminogen activator levels and increases in the levels of blood triglycerides, LDL (low-density lipoprotein) cholesterol, fibrinogen and the von Willebrand factor. Thus, smoking increases blood coagulability and deteriorates the blood lipid profile, resulting in thrombogenetic proneness and dyslipidemia. Smoking also increases the generation of atherogenic oxidized LDL in blood and decreases antiatherogenic prostacyclin production in the vascular endothelium. Smoking cessation is important for the prevention and therapy of PAD, and to this end, counseling by physicians and nicotine replacement therapy are useful and strongly recommended for patients with PAD.

Molecular characterization of peripheral arterial disease in proximal extremity arteries

PURPOSE

Although risk factors for atherosclerosis in peripheral arterial disease (PAD) are well defined, the underlying mechanisms are poorly understood and no medication exists for causal therapy. Molecular pathways that could be targeted have not been identified so far. To address this issue, we compared the molecular profiles of healthy versus PAD proximal femoral arteries.

METHODS

Gene expression profiles from proximal femoral arteries of patients with PAD (Fontaine stage IIb-IV; n = 20) and femoral arteries from healthy controls (CO) (n = 3) were compared by microarray technology. We evaluated all samples by histopathology and performed microdissection on the CO tissue before molecular analysis. We analyzed genes regarding their cellular localization, molecular function, and risk factors such as hypercholesterolemia, smoking, and diabetes. We used a selected panel of genes for polymerase chain reaction validation of microarray results and compared the data with previously published studies.

RESULTS

Most genes overexpressed in PAD versus CO were located in the cytoplasm, membrane, and nucleus. Functionally, they had binding activity to nucleotides, cytoskeletal proteins, and transcription factors. They were mainly involved in immune regulation (e.g., interleukin-8, chemokine ligand 18, and allograft-inflammatory factor-1) (P < 0.01). Down-regulated genes in PAD versus CO were located in the extracellular region. They had transporter and G-protein receptor activity. They were associated with signaling, cell growth, and tissue formation (e.g., myosin VB, marker for differentiated aortic smooth muscle, myosin 11) (P < 0.01). Polymerase chain reaction successfully validated the expression of the differences among 10 selected genes (e.g., chemokine ligand 18, common leukocyte antigen, killer cell lectin-like receptor subfamily B, member 1, and interleukin-8).

CONCLUSIONS

Genes enrolled in immune regulation and inflammatory response were identified as key players in PAD. Various membrane-bound molecules with binding activity are hereunder. Identification of such molecules may elucidate relevant players that act as candidates for therapeutic targets or prognostic markers in the future.

Antioxidants protect against increased risk of atherosclerosis induced by exposure to cigarette smoke: Histological and biochemical study

BACKGROUND AND OBJECTIVES

This study aimed to assess the dose-dependent effect of antioxidants in protection against cardiovascular changes induced by exposure to cigarette smoke.

DESIGN AND SETTING

This was an experimental study, conducted at King Fahd Medical Research Center, King Abdulaziz University.

MATERIALS AND METHODS

This study was carried out on 57 male albino rats divided into nine groups. Rats of experimental groups were exposed to cigarette smoke from a total of 100 cigarettes per week for four weeks in a specially designed chamber. The antioxidants used (vitamin C, E, and B-carotene) were administrated at low (9, 7.2, and 0.27 mg/day) and high doses (18, 14.4, and 0.54 mg/day), respectively, through gastric feeding tubes. The lipid profile was estimated, and the carotids and heart were removed, weighed, and then processed, and the carotid intima-media thickness was measured. Statistical analysis was performed using the Statistical Package for Social Sciences.

RESULTS

The lipid profile was significantly improved in all groups treated with low or high doses of antioxidants after or during the exposure to cigarette smoke. Improvement was marked in the group treated with a high dose of antioxidants. The histological changes, as well as the intima-medial thickness of the carotid artery induced by exposure to cigarette smoke, have been improved by treatment with antioxidants (at either low or high doses), either after or during exposure to cigarette smoke. Improvement was marked in the group treated with a low dose of antioxidant. Treatment with antioxidants could not improve degenerated cardiac muscle fibers, while they could reduce the thickness of the branches of the coronary vessels.

CONCLUSION

These results indicated that antioxidants ameliorated the cigarette smoke contribution to atherosclerosis, but they could not completely reverse the changes induced by cigarette smoke. Simultaneous intake of antioxidants could ameliorate the cigarette-smoke-induced changes apart from those of the heart.

Supervised exercise therapy for intermittent claudication: current status and future perspectives

Intermittent claudication (IC) has a high prevalence in the older population and is closely associated with cardiovascular and cerebrovascular disease. High mortality rates are reported due to ongoing atherosclerotic disease. Because of these serious health risks, treatment of IC should address reduction of cardiovascular events (and related morbidity/mortality) and improvement of the poor health-related quality of life (QoL) and functional capacity. In several randomized clinical trials and systematic reviews, supervised exercise therapy (SET) is compared with non-supervised exercise, usual care, placebo, walking advice or vascular interventions. The current evidence supports SET as the primary treatment for IC. SET improves maximum walking distance and health-related QoL with a marginal risk of co-morbidity or mortality. This is also illustrated in contemporary international guidelines. Community-based SET appears to be at least as efficacious as programs provided in a clinical setting. In the Netherlands, a national integrated care network (ClaudicatioNet) providing specialized care for patients with IC is currently being implemented. Besides providing a standardized form of SET, the specialized physical therapists stimulate medication compliance and perform lifestyle coaching. Future research should focus on the influence of co-morbidities on prognosis and effect of SET outcome and the potential beneficial effects of SET combined with a vascular intervention.

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.

Peripheral artery disease: current insight into the disease and its diagnosis and management

Peripheral artery disease (PAD), which comprises atherosclerosis of the abdominal aorta, iliac, and lower-extremity arteries, is underdiagnosed, undertreated, and poorly understood by the medical community. Patients with PAD may experience a multitude of problems, such as claudication, ischemic rest pain, ischemic ulcerations, repeated hospitalizations, revascularizations, and limb loss. This may lead to a poor quality of life and a high rate of depression. From the standpoint of the limb, the prognosis of patients with PAD is favorable in that the claudication remains stable in 70% to 80% of patients over a 10-year period. However, the rate of myocardial infarction, stroke, and cardiovascular death in patients with both symptomatic and asymptomatic PAD is markedly increased. The ankle brachial index is an excellent screening test for the presence of PAD. Imaging studies (duplex ultrasonography, computed tomographic angiography, magnetic resonance angiography, catheter-based angiography) may provide additional anatomic information if revascularization is planned. The goals of therapy are to improve symptoms and thus quality of life and to decrease the cardiovascular event rate (myocardial infarction, stroke, cardiovascular death). The former is accomplished by establishing a supervised exercise program and administering cilostazol or performing a revascularization procedure if medical therapy is ineffective. A comprehensive program of cardiovascular risk modification (discontinuation of tobacco use and control of lipids, blood pressure, and diabetes) will help to prevent the latter.

Pharmacologic therapy for intermittent claudication

Peripheral artery disease, defined as atherosclerosis in the lower extremities, affects nearly 8.5 million people in the United States. Due to the frequent asymptomatic manifestation of peripheral artery disease, diagnosis may be delayed and its true incidence underestimated. However, some patients may experience aching pain, numbness, weakness, or fatigue, a condition termed intermittent claudication. Peripheral atherosclerosis is associated with cardiovascular risk and physical impairment; therefore, treatment goals are aimed at decreasing cardiovascular risk, as well as improving quality of life. Little debate exists regarding the management of cardiovascular risk reduction, which consists of both antiplatelet therapy and risk factor modification. Despite recently published guidelines, the treatment of intermittent claudication is less well established and the management remains controversial and uncertain. Exercise remains the first-line therapy for intermittent claudication; however, pharmacologic treatment is often necessary. Although only two prescription drugs have been approved by the U.S. Food and Drug Administration for the treatment of intermittent claudication, several supplements and investigational agents have been evaluated. Therapeutic optimization should balance the anticipated improvements in quality of life with the potential safety risks.

Increased apoB/apoA-I Ratio is Predictive of Peripheral Arterial Disease in Initially Healthy 58-Year-old Men during 8.9 Years of Follow-up

The aim of the present study was to investigate, if increased levels of apoB/apoA-I ratios are associated with future peripheral arterial disease as measured by ankle-brachial index. Increased apoB/apoA-I levels are defined as 0.9, which has been suggested for men, and as 0.63, which has observed to be associated with plaques in the femoral artery. The study was performed in a cohort of initially clinically healthy 58-year-old men living in the city of Göteborg, Sweden. The group with an apoB/apoA-I ratio ≥0.9 had a significantly increased risk of having PAD during 8.9 years of follow-up than the group below that level (OR: 2.15 CI: 1.21 to 3.82, p < 0.01). When applying the lower apoB/apoA-I cut off, results showed that the group with a level >0.63 had more than a three-fold risk of future PAD compared to the group ≤0.63 (OR: 3.28 CI: 1.14 to 9.40, p < 0.05).

ApoB/ApoA-I ratio in young patients with ischemic cerebral stroke or peripheral arterial disease

Although smoking and hypertension are classic risk factors for atherothrombotic diseases, the relationship of dyslipidemia and vascular diseases, other than myocardial infarction, is less clearly established, especially in young subjects. In the current study, a detailed analysis of the lipid and apolipoprotein profiles was conducted in young patients of ischemic cerebral stroke (IS) and peripheral arterial disease (PAD). Plasma levels of C-reactive protein (hs-CRP), total cholesterol (TC), high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), triglycerides (TG), and apolipoproteins A-I (ApoA-I) and apolipoproteins B (ApoB), which include the ApoB/ApoA-I ratio, were analyzed in a group of 81 patients who presented with IS (n = 46) or PAD (n = 35) as well as in 167 control subjects. Significant differences were observed for hs-CRP, TC, HDLc, LDLc, TG, ApoA-I, and ApoB levels, as well as for the ApoB/ApoA-I ratio, between the control and the IS or PAD groups. However, after adjustment for sex, age, smoking, hypertension, hs-CRP, and dyslipidemia (LDLc, TC, HDLc, TG, ApoA, ApoB, and ApoB/ApoA-I ratio), hs-CRP, ApoB, and the ApoB/ApoA-I ratio were independently associated with increased risks of IS or PAD. Increased ApoB/ApoA-I ratio and hs-CRP levels are independently associated with occurrence of IS and PAD in young patients and are significant markers of alterations on lipid and apolipoproteic profiles and inflammatory responses, respectively, in these patients.

A variant associated with nicotine dependence, lung cancer and peripheral arterial disease

Smoking is a leading cause of preventable death, causing about 5 million premature deaths worldwide each year. Evidence for genetic influence on smoking behaviour and nicotine dependence (ND) has prompted a search for susceptibility genes. Furthermore, assessing the impact of sequence variants on smoking-related diseases is important to public health. Smoking is the major risk factor for lung cancer (LC) and is one of the main risk factors for peripheral arterial disease (PAD). Here we identify a common variant in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24 with an effect on smoking quantity, ND and the risk of two smoking-related diseases in populations of European descent. The variant has an effect on the number of cigarettes smoked per day in our sample of smokers. The same variant was associated with ND in a previous genome-wide association study that used low-quantity smokers as controls, and with a similar approach we observe a highly significant association with ND. A comparison of cases of LC and PAD with population controls each showed that the variant confers risk of LC and PAD. The findings provide a case study of a gene-environment interaction, highlighting the role of nicotine addiction in the pathology of other serious diseases.

Global DNA methylation is influenced by smoking behaviour

The level of epigenetic DNA methylation is an important factor in the pathogenesis of various human diseases. As smoking may influence DNA methylation, we investigated the effect of smoking habits on global DNA methylation in 298 genomic DNA samples (73 fathers, 69 mothers and 156 offspring). We did not find a direct effect of smoking on global DNA methylation. However, there was an association of the offspring's DNA methylation with paternal DNA methylation that was strongest if both had never smoked (R2corr=0.41, Beta=0.68, p=0.02) and completely vanished if the offspring smoked or had ever smoked. These findings suggest an association between smoking behaviour and global DNA methylation, which may be of importance for a wide range of diseases.

Taking ad-Vantage of lax advertising regulation in the USA and Canada: reassuring and distracting health-concerned smokers

We explored the evolution from cigarette product attributes to psychosocial needs in advertising campaigns for low-tar cigarettes. Analysis of previously secret tobacco industry documents and print advertising images indicated that low-tar brands targeted smokers who were concerned about their health with advertising images intended to distract them from the health hazards of smoking. Advertising first emphasized product characteristics (filtration, low tar) that implied health benefits. Over time, advertising emphasis shifted to salient psychosocial needs of the target markets. A case study of Vantage cigarettes in the USA and Canada showed that advertising presented images of intelligent, upward-striving people who had achieved personal success and intentionally excluded the act of smoking from the imagery, while minimal product information was provided. This illustrates one strategy to appeal to concerned smokers by not describing the product itself (which may remind smokers of the problems associated with smoking), but instead using evocative imagery to distract smokers from these problems. Current advertising for potential reduced-exposure products (PREPs) emphasizes product characteristics, but these products have not delivered on the promise of a healthier alternative cigarette. Our results suggest that the tobacco control community should be on the alert for a shift in advertising focus for PREPs to the image of the user rather than the cigarette. Global Framework Convention on Tobacco Control-style advertising bans that prohibit all user imagery in tobacco advertising could preempt a psychosocial needs-based advertising strategy for PREPs and maintain public attention on the health hazards of smoking.

A contemporary approach to peripheral arterial disease

Peripheral arterial disease is often overlooked by primary care providers because early physical findings are subtle and patients may not complain of symptoms until it is in its advanced stages.

Suboptimal intensity of risk factor modification in PAD

This study extends earlier trials indicating that atherosclerosis risk factors are underdetected and undertreated in peripheral arterial disease (PAD) patients. Recognition and treatment of hyperlipidemia and hypertension in PAD patients is suboptimal. Diabetes appears to be detected more frequently although glycemic control is still suboptimal. The use of antiplatelet therapy is particularly underutilized. Additionally, despite the demonstrated efficacy of regular exercise in PAD patients, almost half of the study sample was sedentary. Approximately one third of the current study sample was overweight and nearly one third was obese by ATP-III guidelines. Only 31% of subjects were taking dietary measures to improve their cardiovascular health, and even fewer were physically active. To rectify suboptimal management of risk factors, there is a need for increased public awareness of PAD, reimbursement and implementation of screening programs and more aggressive treatment. Future studies are needed to examine innovative interventions for identification and management of cardiovascular risk factors in patients with PAD.

Life-style Modification in Peripheral Arterial Disease

OBJECTIVE

To review the published evidence supporting the use of life-style modification in peripheral arterial disease (PAD).

DESIGN

A systematic search of the medical literature was performed for relevant studies.

MATERIALS

The publications obtained were then searched for randomised clinical trials which reported end-points of mortality or major cardiovascular event rates with various life-style modifications.

RESULTS

Only one randomised controlled trial was found reporting relevant end-points. Other trials were of other end-points such as walking distance or biochemical markers.

CONCLUSIONS

There is a lack of randomised controlled data proving the benefit of life-style modification in improving mortality and reducing cardiovascular events in patients with PAD. Despite this there is sufficient evidence to recommend some life-style modification as part of the overall approach to risk reduction in these patients. There is compelling evidence to support smoking cessation, increased exercise and improved diet.

Influence of smoking on incidence and prevalence of peripheral arterial disease

OBJECTIVE

Many studies have been published regarding the influence of smoking on the incidence and prevalence of peripheral arterial disease (PAD). A systematic review was performed to establish the magnitude of the effect of smoking on the development of PAD, and a possible dose-response relationship.

METHODS

English-language articles were reviewed by 2 observers using a standardized form, and were summarized in tabular form. Data were extracted by 2 independent observers. Where possible, outcome data, expressed in terms of prevalence or incidence, were recalculated as odds ratio or relative risk, with never-smokers as the reference group, or if this was not available the nonsmoker group. Most studies did not provide primary data. Therefore the weighted means were reported as a summary estimate, provided that a funnel plot between sample size and observed effect size made publication bias unlikely.

RESULTS

Sixteen articles describing 17 studies were included in the analysis. Four of the studies were prospective, and 13 were cross-sectional. The prevalence of symptomatic PAD was increased 2.3-fold in current smokers. Even in former smokers the prevalence was substantially increased by a factor of 2.6. A clear dose-response relationship, with a strong increase in risk for PAD in heavy smokers was observed. In countries where approximately 30% of the population are smokers, 50% of PAD can be attributed to smoking.

CONCLUSIONS

Smoking is a potent risk factor for symptomatic PAD, with an important and consistent dose-response relationship. With the persistence of high risk for PAD in former smokers, tobacco control programs should continue to advocate smoking cessation, but focus even more on preventing future generations from ever starting to smoke.

The Association Between Fruit and Vegetable Consumption and Peripheral Arterial Disease

BACKGROUND

High fruit and vegetable consumption has been associated with a lower risk of cardiovascular diseases, but few studies have focused on peripheral arterial disease. In this study, we evaluated the association of consumption of fruits and vegetables with peripheral arterial disease.

METHODS

In a cohort of 44,059 men initially free of cardiovascular disease and diabetes, we documented 295 cases of peripheral arterial disease during a 12-year follow-up. Fruit and vegetable consumption was assessed by food frequency questionnaire.

RESULTS

In the age-adjusted model, men in the highest quintile had a relative risk of 0.55 (95% confidence interval = 0.38-0.80) for overall fruit and vegetable intake, 0.52 (0.36-0.77) for fruit intake, and 0.54 (0.36-0.81) for vegetable intake, compared with those in the lowest quintile of intake. However, the associations were greatly weakened after adjustment for smoking and other traditional cardiovascular disease risk factors. Comparing men in the highest quintile versus the lowest quintile, relative risks and 95% confidence intervals were 0.95 (0.62-1.44) for overall fruit and vegetable intake, 0.97 (0.64-1.48) for fruit intake, and 0.76 (0.50-1.17) for vegetable intake.

CONCLUSIONS

We did not find evidence that fruit and vegetable consumption protects against peripheral arterial disease, although a modest benefit cannot be excluded.

Epidemiology of smoking-induced cardiovascular disease

Cigarette smoking is a major cause of coronary heart disease, stroke, aortic aneurysm, and peripheral vascular disease. The risk is manifest both as an increased risk for thrombosis of narrowed vessels and as an increased degree of atherosclerosis in those vessels. The cardiovascular risks owing to cigarette smoking increase with the amount smoked and with the duration of smoking. Risks are not reduced by smoking cigarettes with lower machine-measured yields of tar and nicotine, but those who have only smoked pipes or cigars seem to have a lower risk for cardiovascular diseases. Cessation of cigarette smoking reduces disease risks, although risks may remain elevated for a decade or more after cessation.

Comorbidities and exercise capacity in older patients with intermittent claudication

Patients with peripheral arterial disease (PAD) and intermittent claudication often have coronary artery disease (CAD) and other comorbid medical problems. There is a paucity of information on the impact of coexistent medical conditions on exercise capacity and functional status in patients with PAD. This study examined the impact of CAD, diabetes, cigarette smoking, prior peripheral surgical revascularization and other medical conditions on claudication pain times and peak oxygen capacity (VO2) during maximal effort treadmill testing in 119 male outpatient volunteers (ankle-brachial index (ABI) of 0.65 +/- 0.2, mean +/- SEM) with a history of Fontaine Stage II PAD. Smoking status was significantly related to ambulatory function. Current smokers had a lower peak VO2 expressed in l/min than either former or never smokers (ANCOVA adjusted for age, p = 0.003). However, after adjustment for body weight, there was only a trend for a difference in peak VO2 between current (13.2 +/- 0.5 ml/kg per min), former (14.2 +/- 0.4 ml/kg per min) and never (15.4 +/- 1.0 ml/kg per min) smokers (ANCOVA, p = 0.10). Current smokers had a shorter time to onset of claudication pain (p = 0.023) and shorter maximal claudication pain times (p = 0.029) than former or never smokers (p = 0.023). The ABI 1 min after cessation of exercise was also lower in smokers compared to former and never smokers (p = 0.018). There were no significant differences in functional performance measures or time to recovery from maximal claudication pain when patients were categorized on the presence or absence of CAD, diabetes, peripheral revascularization, arthritis, hypertension or dyslipidemia. Therefore, smoking adversely affected exercise capacity in these PAD patients, whereas the presence of CAD, diabetes and other medical problems had a relatively minor impact on exercise capacity. In conclusion, the relatively minor impact of comorbid medical conditions on walking ability in patients with PAD reflects the overwhelming limitation in ambulatory function due to the claudication pain.

Dose-years as an improved index of cumulative tobacco smoke exposure

In assessing the link between tobacco smoking and disease, it is important to determine longterm, cumulative exposure to tobacco smoke as accurately as possible. Conventional methods of assessing exposure to tobacco smoke each have intrinsic limitations. Self-reporting of tobacco use, and the conversion of this data to pack-years, can be prone to error due to individuals wishing to conceal smoking habits, inaccurate reporting of daily cigarette consumptions or years of smoking, and failure to take into account the variation that exists in inter-individual smoking experiences. Measurement of cotinine, a major metabolite of nicotine in humans, is a reliable method of monitoring recent doses of tobacco smoke exposure. Cotinine concentrations, however, may remain stable in smokers over the longer term. Therefore, dose-years, and more specifically cotinine-years, may represent an improved index of cumulative tobacco smoke exposure.

Health impact of "reduced yield" cigarettes: a critical assessment of the epidemiological evidence

Cigarettes with lower machine measured "tar" and nicotine yields have been marketed as "safer" than high tar products over the last four decades, but there is conflicting evidence about the impact of these products on the disease burden caused by smoking. This paper critically examines the epidemiological evidence relevant to the health consequences of "reduced yield" cigarettes. Some epidemiological studies have found attenuated risk of lung cancer but not other diseases, among people who smoke "reduced yield" cigarettes compared to smokers of unfiltered, high yield products. These studies probably overestimate the magnitude of any association with lung cancer by over adjusting for the number of cigarettes smoked per day (one aspect of compensatory smoking), and by not fully considering other differences between smokers of "high yield" and "low yield" cigarettes. Selected cohort studies in the USA and UK show that lung cancer risk continued to increase among older smokers from the 1950s to the 1980s, despite the widespread adoption of lower yield cigarettes. The change to filter tip products did not prevent a progressive increase in lung cancer risk among male smokers who began smoking during and after the second world war compared to the first world war era smokers. National trends in vital statistics data show declining lung cancer death rates in young adults, especially males, in many countries, but the extent to which this is attributable to "reduced yield" cigarettes remains unclear. No studies have adequately assessed whether health claims used to market "reduced yield" cigarettes delay cessation among smokers who might otherwise quit, or increase initiation among non-smokers. There is no convincing evidence that past changes in cigarette design have resulted in an important health benefit to either smokers or the whole population. Tobacco control policies should not allow changes in cigarette design to subvert or distract from interventions proven to reduce the prevalence, intensity, and duration of smoking.

Cigarette smoking, endothelial injury and cardiovascular disease

Despite the fact that the epidemiological evidence linking cigarette smoking with cardiovascular disease is overwhelming, the precise components of cigarette smoke responsible for this relationship and the mechanisms by which they exert their effect have not yet been elucidated. There are however, some promising pointers as a result of recent developments and this review concentrates on new evidence since earlier reviews of this topic. It is now known that the endothelium has a vastly more important role than was ever thought to be the case a decade ago. Its role in health and disease is increasingly understood, as is the relationship between endothelial injury and the development of atherosclerosis. There is considerable evidence that cigarette smoking can result in both morphological and biochemical disturbances to the endothelium both in vivo and in cell culture systems. Cigarette smoke is a complex mixture and only a few components have been extensively studied. Nicotine and carbon monoxide are much less damaging than is whole smoke. However the free radical components of cigarette smoke have been shown to cause damage in model systems. Further work will be necessary to consolidate the evidence base but the data reported in this review suggest that the free radical components of cigarette smoke may be responsible for the morphological and functional damage to endothelium that has been observed in model systems.

Smoking characteristics, antioxidant vitamins, and carotid artery wall thickness among life-long smokers

We studied the associations between the common carotid-intima-media thickness (IMT), as a marker of atherosclerosis, and smoking characteristics and antioxidant vitamins among 158 male life-long cardiovascular disease (CVD)-free smokers. An "increased" carotid IMT was defined as the upper 25%. The prevalence of increased IMT was 2.5 times (odds ratio (OR) = 2.5; 95% CI: 1.1, 5.6) higher among smokers inhaling smoke deeply into the lungs than among moderate and non-inhalers. This association decreased when adjusted for other CVD risk factors. Smokers with an increased carotid IMT did not differ significantly in mean antioxidant vitamin intake and status with the remaining group. However, classical CVD risk factors contributed importantly to increased carotid IMT. In our study, depth of inhalation was the only smoking characteristic associated with carotid IMT although attenuated after adjustment for traditional risk factors for CVD. Furthermore, in these life-long smokers not using any vitamin supplements, no associations were found for antioxidant vitamins.

Vascular damage from smoking: disease mechanisms at the arterial wall

The products of tobacco combustion are absorbed into the systemic circulation. Absorbed nicotine stimulates the release of catecholamines, whilst other products (perhaps including nicotine) injure the arterial endothelium and promote atherogenesis. Free radicals and aromatic compounds diminish the endothelial synthesis of nitric oxide, causing impaired endothelium-dependent relaxation of arteries, the earliest clinical sign of endothelial dysfunction. Smoking alters the shear forces and rheology at the endothelial surface and these changes enhance the effects of products of tobacco combustion to upregulate leucocyte adhesion molecules on the endothelial surface. The increased oxidation of low density lipoprotein (LDL) in smokers has synergistic effects to promote monocyte adhesion and monocyte migration into the subintimal space. Continued stimulation of intimal cells by oxidized LDL leads to the development of atherosclerosis. Many of these effects are ameliorated by high concentrations of vitamin C. Smoking also potentiates thrombosis at the dysfunctional endothelium by increasing the concentration of plasma fibrinogen and altering the activity of platelets. All these proatherogenic effects of smoking to injure the endothelium also are observed, albeit to lesser extent, in passive smokers.