Association of chronic kidney disease categories defined with different formulae with major adverse events in patients with peripheral vascular disease

Rates of Stroke in Patients With Different Presentations of Carotid Artery Stenosis

OBJECTIVE

Carotid artery stenosis may present without the classical symptoms of transient ischaemic attack or stroke but the rates of stroke for these presentations is unknown. The aim of this study was to examine the rates of stroke in patients with different presentations of carotid artery stenosis.

METHODS

A multicentre prospective cohort study was conducted across three Australian vascular centres with low rates of surgical treatment of patients without transient ischaemic attack or stroke. Patients with a 50 - 99% carotid artery stenosis presenting with non-focal symptoms (e.g., dizziness or syncope; n = 47), prior contralateral carotid endarterectomy (n = 71), prior ipsilateral symptoms more than six months earlier (n = 82), and no symptoms (n = 304) were recruited. The primary outcome was ipsilateral ischaemic stroke. Secondary outcomes were any ischaemic stroke and cardiovascular death. Data were analysed using Cox proportional hazard and Kaplan-Meier analyses.

RESULTS

Between 2002 and 2020, 504 patients were enrolled (mean age 71 years, 30% women) and followed for a median of 5.1 years (interquartile range 2.5, 8.8; 2 981 person years). Approximately 82% were prescribed antiplatelet therapy, 84% were receiving at least one antihypertensive drug, and 76% were prescribed a statin at entry. After five years the incidence of ipsilateral stroke was 6.5% (95% confidence interval [CI] 4.3 - 9.5). There were no statistically significant differences in the annual rate of ipsilateral stroke among people with non-focal symptoms (2.1%; 95% CI 0.8 - 5.7), prior contralateral carotid endarterectomy (0.2%; 0.03 - 1.6) or ipsilateral symptoms > 6 months prior (1.0%; 0.4 - 2.5) compared with those with no symptoms (1.2%; 0.7 - 1.8; p = .19). There were no statistically significant differences in secondary outcomes across groups.

CONCLUSION

This cohort study showed no large differences in stroke rates among people with different presentations of carotid artery stenosis.

Association between aortic peak wall stress and rupture index with abdominal aortic aneurysm-related events

OBJECTIVE

The aim of this study was to assess whether aortic peak wall stress (PWS) and peak wall rupture index (PWRI) were associated with the risk of abdominal aortic aneurysm (AAA) rupture or repair (defined as AAA events) among participants with small AAAs.

METHODS

PWS and PWRI were estimated from computed tomography angiography (CTA) scans of 210 participants with small AAAs (≥ 30 and  ≤ 50 mm) prospectively recruited between 2002 and 2016 from two existing databases. Participants were followed for a median of 2.0 (inter-quartile range 1.9, 2.8) years to record the incidence of AAA events. The associations between PWS and PWRI with AAA events were assessed using Cox proportional hazard analyses. The ability of PWS and PWRI to reclassify the risk of AAA events compared to the initial AAA diameter was examined using net reclassification index (NRI) and classification and regression tree (CART) analysis.

RESULTS

After adjusting for other risk factors, one standard deviation increase in PWS (hazard ratio, HR, 1.56, 95% confidence intervals, CI 1.19, 2.06; p = 0.001) and PWRI (HR 1.74, 95% CI 1.29, 2.34; p < 0.001) were associated with significantly higher risks of AAA events. In the CART analysis, PWRI was identified as the best single predictor of AAA events at a cut-off value of  > 0.562. PWRI, but not PWS, significantly improved the classification of risk of AAA events compared to the initial AAA diameter alone.

CONCLUSION

PWS and PWRI predicted the risk of AAA events but only PWRI significantly improved the risk stratification compared to aortic diameter alone.

KEY POINTS

• Aortic diameter is an imperfect measure of abdominal aortic aneurysm (AAA) rupture risk. • This observational study of 210 participants found that peak wall stress (PWS) and peak wall rupture index (PWRI) predicted the risk of aortic rupture or AAA repair. • PWRI, but not PWS, significantly improved the risk stratification for AAA events compared to aortic diameter alone.

The predictive value of four serum biomarkers for major adverse events in patients with small abdominal aortic aneurysm

BACKGROUND

The primary aim of this study was to test which of a group of four inflammation and thrombosis biomarkers were independently predictive of major adverse cardiovascular events (MACE) in patients with small abdominal aortic aneurysm (AAA).

METHODS

A total of 471 participants with a 30- to 54-mm AAA had serum C-reactive protein (CRP), fibrinogen, neutrophil-lymphocyte ratio (NLR), and homocysteine measured. The primary outcome was MACE, which was defined as the first occurrence of myocardial infarction, stroke, or cardiovascular death. The association of biomarkers with events was assessed using Kaplan-Meier and Cox proportional hazard analyses. The net improvement in risk of event categorization with addition of a biomarker to clinical risk factors alone was assessed using net reclassification index.

RESULTS

Participants were followed for a median of 2.4 years (interquartile range, 0.8-5.4 years), and 102 (21.7%) had a MACE. The incidence of MACE was 13.2% in participants with CRP >3.0 mg/L, compared with 10.1% in those with CRP ≤3.0 mg/L at 2.5 years (P = .047). After adjusting for other risk factors, higher CRP was associated with a significantly higher risk of MACE (hazard ratio, 1.19; 95% confidence interval, 1.05-1.35). None of the other biomarkers were associated with the risk of MACE. According to the net reclassification index, CRP significantly improved the risk classification of MACE compared with clinical risk factors alone.

CONCLUSIONS

CRP can assist in classification of risk of MACE for patients with small AAA.

Protocol for the Metformin Aneurysm Trial (MAT): a placebo-controlled randomised trial testing whether metformin reduces the risk of serious complications of abdominal aortic aneurysm

Background

Multiple observational studies have associated metformin prescription with reduced progression of abdominal aortic aneurysm (AAA). The Metformin Aneurysm Trial (MAT) will test whether metformin reduces the risk of AAA rupture-related mortality or requirement for AAA surgery (AAA events) in people with asymptomatic aneurysms.

Methods

MAT is an international, multi-centre, prospective, parallel-group, randomised, placebo-controlled trial. Participants must have an asymptomatic AAA measuring at least 35 mm in maximum diameter, no diabetes, no contraindication to metformin and no current plans for surgical repair. The double-blind period is preceded by a 6-week, single-blind, active run-in phase in which all potential participants receive metformin. Only patients tolerating metformin by taking at least 80% of allocated medication will enter the trial and be randomised to 1500 mg of metformin XR or an identical placebo. The primary outcome is the proportion of AAA events defined as rupture-related mortality or need for surgical repair. Secondary outcomes include AAA growth, major adverse cardiovascular events and health-related quality of life. In order to test if metformin reduced the risk of AAA events by at least 25%, 616 primary outcome events will be required (power 90%, alpha 0.05).

Discussion

Currently, there is no drug therapy for AAA. Past trials have found no convincing evidence of the benefit of multiple blood pressure lowering, antibiotics, a mast cell inhibitor, an anti-platelet drug and a lipid-lowering medication on AAA growth. MAT is one of a number of trials now ongoing testing metformin for AAA. MAT, unlike these other trials, is designed to test the effect of metformin on AAA events. The international collaboration needed for MAT will be challenging to achieve given the current COVID-19 pandemic. If this challenge can be overcome, MAT will represent a trial unique within the AAA field in its large size and design.

Trial registration

Australian Clinical Trials ACTRN12618001707257. Registered on 16 October 2018

Cohort Study Examining the Prevalence and Relationship with Outcome of Standard Modifiable Risk Factors in Patients with Peripheral Artery Occlusive and Aneurysmal Disease

OBJECTIVE

The aim was to examine the presentation and outcome of patients with peripheral artery occlusive and aneurysmal disease (POAD) in relation to standard modifiable cardiovascular risk factors (SMuRFs; i.e., hypertension, diabetes, hypercholesterolaemia, and smoking).

METHODS

A total of 2 129 participants with POAD were recruited from three vascular clinics in Queensland, Australia. SMuRFs were defined using established criteria. Participants were followed via outpatient appointments and linked data to record the primary outcome event of major adverse cardiovascular events (MACE). The association between SMuRFs and MACE was assessed using Cox proportional hazard analysis. Subanalyses examined the association of individual SMuRFs with MACE and assessed findings separately in participants with occlusive and aneurysmal disease.

RESULTS

At recruitment 71 (3.3%), 551 (25.9%), 977 (45.9%), 471 (22.1%), and 59 (2.8%) participants had zero, one, two, three, and four SMuRFs. During a median follow up of 2.6 (interquartile range 0.4, 6.2) years, the risk of MACE was progressively higher with the increasing numbers of SMuRFs (adjusted hazard ratio [HR] 95% confidence interval [CI] 4.09, 1.29 - 12.91; 4.28, 1.37 - 13.41; 5.82, 1.84 - 18.39; and 9.42, 2.77 - 32.08; for one, two, three, or four SMuRFs, respectively) by comparison with those who were SMuRF-less at recruitment. Participants with occlusive disease were significantly more likely to have a greater number of SMuRFs than those with aneurysmal disease. In a subanalysis, there was a significantly higher risk of MACE with three or four SMuRFs in participants presenting with either occlusive or aneurysmal disease compared with those who were SMuRF-less. Hypertension, diabetes, and smoking but not hypercholesterolaemia were independently associated with increased risk of MACE.

CONCLUSION

Very few patients presenting with POAD had no SMuRFs. There was a progressive increase in the risk of MACE in relation to the number of SMuRFs identified at entry.

Editor's Choice - Cohort Study Examining the Association Between Abdominal Aortic Size and Major Adverse Cardiovascular Events in Patients with Aortic and Peripheral Occlusive and Aneurysmal Disease

OBJECTIVE

The aim of this study was to examine whether there were independent associations between abdominal aortic diameter, size index, and height index and the risk of major adverse events in patients referred for treatment of various types of aortic and peripheral occlusive and aneurysmal disease (APOAD).

METHODS

In total, 1 752 participants with a variety of APOADs were prospectively recruited between 2002 and 2020 and had a maximum abdominal aortic diameter, aortic size index (aortic diameter relative to body surface area), and aortic height index (aortic diameter relative to height) measured by ultrasound at recruitment. Participants were followed for a median of 4.6 years (interquartile range 2.0 - 8.0 years) to record outcome events, including major adverse cardiovascular events (MACE), peripheral artery surgery, abdominal aortic aneurysm (AAA) events (rupture or repair), and all cause mortality. The association between aortic size and events was assessed using Cox proportional hazard analysis. The ability of aortic size to improve risk of events classification was assessed using the net reclassification index (NRI).

RESULTS

After adjusting for other risk factors, larger aortic diameter was associated with an increased risk of MACE (hazard ratio [HR] 1.17, 95% confidence interval [CI] 1.05 - 1.31), requirement for peripheral artery surgery (HR 2.05, 95% CI 1.90 - 2.22), AAA events (HR 3.01, 95% CI 2.77 - 3.26), and all cause mortality (HR 1.20, 95% CI 1.08 - 1.32). Findings were similar for aortic size and aortic height indices. According to the NRI, all three aortic size measures significantly improved classification of risk of peripheral artery surgery and AAA events but not MACE. Aortic size index, but not aortic diameter or aortic height index, significantly improved the classification of all cause mortality risk.

CONCLUSION

Larger abdominal aortic diameter, size index, and height index are all independently associated with an increased risk of major adverse events in patients with established vascular disease.

Urinary C-peptide/creatinine ratio: A useful biomarker of insulin resistance and refined classification of type 2 diabetes mellitus

BACKGROUND

The urinary C-peptide/creatinine ratio (UCPCR) is low in patients with type 1 diabetes mellitus, but it has not been well characterized in patients with type 2 diabetes mellitus (T2DM). We aimed to measure the UCPCRs in patients with T2DM and explore the relationships among UCPCR, insulin resistance (IR), and chronic vascular complications of diabetes.

METHODS

A cross-sectional study was performed of 1299 Chinese hospitalized patients with T2DM. Binary logistic regression was used to evaluate the relationships between the chronic vascular complications of diabetes and UCPCR. K-means analysis was used to allocate participants to subgroups with five to six variables (age at diagnosis, body mass index [BMI], glycosylated hemoglobin, homoeostasis model assessment 2-estimated beta-cell function (HOMA2-B), and HOMA2-insulin resistance (HOMA2-IR), with or without UCPCR).

RESULTS

UCPCR positively correlated with HOMA2-IR (r = 0.448, P < .001). After adjustment for sex, age, duration of diabetes, and other cardiovascular risk factors, UCPCR was positively associated with diabetic kidney disease (DKD) (odds ratio [OR] = 1.198, 95% CI 1.019-1.408, P = .029) and coronary heart disease (CHD) (OR = 1.312, 95% CI 1.079-1.594, P = .006). When UCPCR was added, cluster analysis using the six variables identified five subgroups of T2DM, characterized by differing age at diagnosis, BMI, beta-cell function, IR, and prevalence of vascular complications.

CONCLUSIONS

UCPCR is positively associated with IR, DKD, and CHD and represents a promising biomarker that could refine the classification of T2DM.

Association of Diagnosis of Depression and Small Abdominal Aortic Aneurysm Growth

BACKGROUND

Depression is associated with an increased risk of cardiovascular events but its association with abdominal aortic aneurysm (AAA) progression is unknown. This study examined if a diagnosis of depression was association with more rapid AAA growth.

METHODS

Patients with small AAA measuring between 30 and 50 mm were recruited from surveillance programs at 4 Australian centres. Maximum AAA diameter was measured by ultrasound imaging using a standardised and reproducible protocol to monitor AAA growth. Depression was defined from medical records of treatment for depression at recruitment. Linear mixed effects modelling was performed to examine the independent association of depression with AAA growth. A propensity matched sub-analysis was performed.

RESULTS

A total of 574 participants were included of whom 73 (12.7%) were diagnosed with depression. Participants were followed with a median of 3 (Inter-quartile range (IQR): 2, 5) ultrasound scans for a median of 2.1 (IQR: 1.1, 3.5) years. The unadjusted model suggested that annual AAA growth was non-significantly reduced (mean difference: -0.3 mm/year; 95% confidence interval (CI): -0.7, 0.2; P = 0.26) in participants with a diagnosis of depression compared to other participants. After adjustment for covariates, depression was not significantly associated with AAA growth (mean difference: -0.3 mm/year; 95% CI: -0.8, 0.2; P = 0.27). Findings were similar in the propensity matched sub-analysis. Sensitivity analyses investigating the impact of initial AAA diameter and follow up on the association of depression with AAA growth found no interaction.

CONCLUSIONS

This study suggested that depression was not associated with faster AAA growth.

Association of chronic venous disease with major adverse cardiovascular events

OBJECTIVE

The aim of the present study was to examine whether severe chronic venous disease (CVD) is associated with a greater risk of major adverse cardiovascular events (MACE) compared with mild CVD.

METHODS

Participants with CVD were prospectively recruited from outpatient vascular departments at two hospitals in North Queensland, Australia. CVD severity was ascertained by vascular specialists using the CEAP (clinical, etiologic, anatomic, pathophysiologic) classification. MACE, defined as myocardial infarction, stroke, or cardiovascular death, were identified from the outpatient follow-up and linked medical records. Kaplan-Meier and Cox proportional hazard analyses were used to examine the association of CVD severity with the occurrence of MACE. A subanalysis was performed in which participants with CEAP C5 and C6 (severe CVD) were compared with those with CEAP C2 to C4 (mild CVD).

RESULTS

A total of 774 participants were included and followed up for a median of 3.09 years (interquartile range, 1.09-8.14 years). The participants with C6 CVD (n = 69) had a threefold greater risk of MACE (hazard ratio, 3.03; 95% confidence interval, 1.02-9.03; P = .046) compared with those with C2 CVD (n = 326) after adjusting for other risk factors. Participants with severe CVD had an increased risk of MACE compared with those with mild CVD (adjusted hazard ratio, 2.37; 95% confidence interval, 1.12-5.04; P = .024).

CONCLUSIONS

Individuals with severe CVD have an increased risk of MACE compared with those with mild CVD, independently of traditional risk factors. Further research is required to clarify the cause of the excess risk.

Control of modifiable risk factors and major adverse cardiovascular events in people with peripheral artery disease and diabetes

BACKGROUND

People with diabetes and peripheral artery disease (PAD) have a high risk of major adverse cardiovascular events (MACE). Prior research suggests that medical therapies aimed to control modifiable risk factors are poorly implemented in patients with PAD.

AIM

To examine the association between the control of modifiable risk factors, estimated by the novel PAD-medical score, and the incidence of MACE in people with PAD and diabetes.

METHODS

Participants were recruited from out-patient clinics if they had a diagnosis of both PAD and diabetes. Control of reversible risk factors was assessed by a new composite measure, the PAD-medical score. This score takes into account the control of low-density lipoprotein cholesterol, blood pressure, blood glucose, smoking and prescription of an anti-platelet. Participants were followed to record incidence of myocardial infarction, stroke and cardiovascular death (MACE). The association of PAD-medical score with MACE was assessed using Cox proportional hazard analyses adjusting for age, sex and prior history of ischemic heart disease and stroke.

RESULTS

Between 2002 and 2020, a total of 424 participants with carotid artery disease (n = 63), aortic or peripheral aneurysm (n = 121) or lower limb ischemia (n = 240) were prospectively recruited, and followed for a median duration (inter-quartile range) of 2.0 (0.2–4.4) years. Only 33 (7.8%) participants had the optimal PAD-medical score of five, with 318 (75%) scoring at least three out of five. There were 89 (21.0%) participants that had at least one MACE during the follow-up period. A one-unit higher PAD-medical score was associated with lower risk of MACE (HR = 0.79, 95%CI: 0.63-0.98) after adjusting for other risk factors.

CONCLUSION

The PAD-medical score provides a simple way to assess the control of modifiable risk factors targeted by medical management aimed to reduce the incidence of MACE.

Association of gout with major adverse cardiovascular events and all-cause mortality in patients with peripheral artery disease

BACKGROUND AND AIMS

Prior epidemiological studies have suggested that individuals with gout are at greater risk of cardiovascular events, but there have been no studies in people with peripheral artery disease (PAD). The aim of this study was to investigate the relationship between gout and major adverse cardiovascular events (MACE) and all-cause mortality in people with PAD.

METHODS

Participants with a range of PAD presentations, including carotid artery disease, aortic or peripheral aneurysm and lower limb PAD, were prospectively recruited from outpatient vascular departments within Australia. MACE (myocardial infarction, stroke or cardiovascular death) and all-cause mortality were identified through out-patient follow-up and linked medical records. Propensity-score matching was undertaken to generate a matched cohort of patients with and without a history of gout. Kaplan-Meier survival analysis and Cox-proportional hazard analysis were used to examine the association of gout with MACE and all-cause mortality.

RESULTS

A total of 4308 people with PAD, of whom 334 had a history of gout, were included and followed for a median (inter-quartile range) of 2.1 (0.1-5.9) years. In the unadjusted analyses, participants with gout were at increased risk of MACE (hazard ratio, HR 1.37, 95% confidence intervals, CI 1.09-1.71, p = 0.006) and all-cause mortality (HR 1.38, 95% 1.13-1.68, p = 0.002), however, the associations were lost in the adjusted analyses. In the propensity-score matched cohort, gout was not significantly associated with an increased risk for MACE or all-cause mortality.

CONCLUSIONS

Gout was not independently associated with increased cardiovascular events in PAD patients.

A Randomised Controlled Trial Assessing the Effects of Peri-operative Fenofibrate Administration on Abdominal Aortic Aneurysm Pathology: Outcomes From the FAME Trial

OBJECTIVE

Experimental studies suggest that fenofibrate prevents abdominal aortic aneurysm (AAA) development by lowering aortic osteopontin (OPN) concentration and reducing the number of macrophages infiltrating the aortic wall. The current study examined the effects of a short course of fenofibrate on AAA pathology in people with large AAAs awaiting aortic repair.

METHODS

This randomised double blind parallel trial included male and female participants aged ≥ 60 years who had an asymptomatic AAA measuring ≥ 50 mm and were scheduled to undergo open AAA repair. Participants were allocated to fenofibrate (145 mg/day) or matching placebo for at least two weeks before elective AAA repair. Blood samples were collected at recruitment and immediately prior to surgery. AAA biopsies were obtained during aortic surgery. The primary outcomes were (1) AAA OPN concentration; (2) serum OPN concentration; and (3) number of AAA macrophages. Exploratory outcomes included circulating and aortic concentrations of other proteins previously associated with AAA. Outcomes assessed at a single time point were compared using logistic regression. Longitudinal outcomes were compared using linear mixed effects models.

RESULTS

Forty-three participants were randomised. After three withdrawals, 40 were followed until the time of surgery (21 allocated fenofibrate and 19 allocated placebo). As expected, serum triglycerides reduced significantly from recruitment to the time of surgery in participants allocated fenofibrate. No differences in any of the primary and exploratory outcomes were observed between groups.

CONCLUSION

A short course of 145 mg of fenofibrate/day did not lower concentrations of OPN or aortic macrophage density in people with large AAAs.

Cohort Study Examining the Association Between Blood Pressure and Cardiovascular Events in Patients With Peripheral Artery Disease

Background Hypertension is an important risk factor for cardiovascular events in patients with peripheral artery disease; however, optimal blood pressure targets for these patients are poorly defined. This study investigated the association between systolic blood pressure ( SBP ) and cardiovascular events in a prospectively recruited patient cohort with peripheral artery disease. Methods and Results A total of 2773 patients were included and were grouped according to SBP at recruitment (≤120 mm Hg, n=604; 121-140 mm Hg, n=1065; and >140 mm Hg, n=1104). Adjusted Cox proportional hazards analyses suggested that patients with SBP ≤120 mm Hg were at greater risk of having a major cardiovascular event (myocardial infarction, stroke, or cardiovascular death) than patients with SBP of 121-140 mm Hg (adjusted hazard ratio, 1.36; 95% CI, 1.08-1.72; P=0.009). Patients with SBP >140 mm Hg had an adjusted hazard ratio of 1.23 (95% CI, 1.00-1.51; P=0.051) of major cardiovascular events compared with patients with SBP of 121-140 mm Hg. These findings were similar in sensitivity analyses only including patients receiving antihypertensive medications or focused on patients with a minimum of 3 months of follow-up. Conclusions This cohort study suggests that patients with peripheral artery disease and SBP ≤120 mm Hg are at increased risk of major cardiovascular events. The findings suggest caution in intensive SBP lowering in this patient group.

Association of Serum Lipoprotein (a) With the Requirement for a Peripheral Artery Operation and the Incidence of Major Adverse Cardiovascular Events in People With Peripheral Artery Disease

Background The aim of this study was to assess the relationship between serum lipoprotein (a) (Lp[a]) concentration and the requirement for peripheral artery disease (PAD) operations or incidence of major adverse cardiovascular events. Methods and Results A total of 1472 people with PAD presenting with intermittent claudication (n=355), abdominal aortic aneurysm (n=989) or critical limb ischemia (n=128) were prospectively recruited from 4 outpatient clinics in Australia. Lp(a) was measured in serum samples collected at recruitment using an immunoassay. Participants were followed for a median (interquartile range) of 2.4 (0.1-6.1) years to record requirement for any PAD operation, defined to include any open or endovascular PAD intervention (lower limb peripheral revascularization, abdominal aortic aneurysm repair, other aneurysm repair, or carotid artery revascularization). Myocardial infarctions, strokes, and deaths were also recorded. The association of Lp(a) with events was assessed using Cox proportional hazard analysis adjusting for traditional risk factors. Participants with Lp(a) ≥30 mg/dL had a greater requirement for any PAD operation (hazard ratio, 1.20, 95% CI, 1.02-1.41) and lower limb peripheral revascularization alone (hazard ratio 1.33, 95% CI, 1.06-1.66) but no increased risk of major adverse cardiovascular events or all-cause mortality. Lp(a) ≥50 mg/dL and a 40 mg/dL increase in Lp(a) were also associated with an increased risk of lower limb peripheral revascularization alone but not with other outcomes. Conclusions In participants with PAD referred for hospital management those with high Lp(a) had greater requirement for lower limb peripheral revascularization but Lp(a) was not consistently associated with other clinical events.

Randomized Placebo-Controlled Trial Assessing the Effect of 24-Week Fenofibrate Therapy on Circulating Markers of Abdominal Aortic Aneurysm: Outcomes From the FAME -2 Trial

Background

There is no drug therapy for abdominal aortic aneurysm (AAA). FAME‐2 (Fenofibrate in the Management of Abdominal Aortic Aneurysm 2) was a placebo‐controlled randomized trial designed to assess whether administration of 145 mg of fenofibrate/d for 24 weeks favorably modified circulating markers of AAA.

Methods and Results

Patients with AAAs measuring 35 to 49 mm and no contraindication were randomized to fenofibrate or identical placebo. The primary outcome measures were the differences in serum osteopontin and kallistatin concentrations between groups. Secondary analyses compared changes in the circulating concentration of AAA‐associated proteins, and AAA growth, between groups using multivariable linear mixed‐effects modeling. A total of 140 patients were randomized to receive fenofibrate (n=70) or placebo (n=70). By the end of the study 3 (2.1%) patients were lost to follow‐up and 18 (12.9%) patients had ceased trial medication. A total of 85% of randomized patients took ≥80% of allocated tablets and were deemed to have complied with the medication regimen. Patients’ allocated fenofibrate had expected reductions in serum triglycerides and estimated glomerular filtration rate, and increases in serum homocysteine. No differences in serum osteopontin, kallistatin, or AAA growth were observed between groups.

Conclusions

Administering 145 mg/d of fenofibrate for 24 weeks did not significantly reduce serum concentrations of osteopontin and kallistatin concentrations, or rates of AAA growth in this trial. The findings do not support the likely benefit of fenofibrate as a treatment for patients with small AAAs.

Clinical Trial Registration

URL: http://www.anzctr.org.au. Unique identifier: ACTRN12613001039774.

Association of Computed Tomographic Leg Muscle Characteristics With Lower Limb and Cardiovascular Events in Patients With Peripheral Artery Disease

Background Poor lower extremity physical performance is an independent predictor of unfavorable outcome in patients with peripheral artery disease ( PAD ); however, few studies have assessed muscle characteristics on imaging directly. Method and Results A novel 3-dimensional semi-automated protocol was developed to estimate leg muscle volume and density (mean attenuation) from computed tomography images. Patients with PAD who underwent a lower extremity computed tomography scan at a tertiary vascular surgery center were included, and were followed up using hospital records and linked data as part of a retrospective cohort study. The primary outcomes were lower limb events (major amputation or peripheral revascularization) and cardiovascular events (myocardial infarction, stroke, or cardiovascular death). Two hundred and twenty-three patients with PAD were included (median age 69.0 years; 73% men) and followed for a median of 4.9 [2.6-7.0] years. During this time there were 99 index lower limb events and 97 cardiovascular events. Low leg muscle density was associated with increased risk of lower limb (rate ratio 1.41 [1.11-1.80] per SD reduction) and cardiovascular events (rate ratio 1.60 [1.29-1.99] per SD reduction). Low muscle density remained an independent predictor of cardiovascular (but not lower limb) events, after adjusting for age, sex, traditional cardiovascular risk factors, and angiographic PAD severity (rate ratio 1.39 [1.09-1.77] per lower SD ). In contrast, leg muscle volume was not associated with outcomes after adjusting for risk factors and PAD severity. Conclusions Low leg muscle density, but not volume, is a strong, independent predictor of major cardiovascular events among people with PAD . Further research is needed to understand the mechanisms underlying these associations.

Within- and Between-Body-Site Agreement of Skin Autofluorescence Measurements in People With and Without Diabetes-Related Foot Disease

BACKGROUND

Skin autofluorescence has been used to assess longer term glycemic control and risk of complications. There is however no agreed site at which autofluorescence should be measured. This study evaluated the within- and between-site agreement in measurement of skin autofluorescence using a noninvasive advanced glycation end product (AGE) reader.

METHODS

Overall, 132 participants were included: 16 with diabetes-related foot ulcers (DFU), 63 with diabetes but without foot ulcers (DMC), 53 without diabetes or foot ulcers (HC). Skin autofluorescence was measured using the AGE Reader (DiagnOptics technologies BV, the Netherlands). Three consecutive skin autofluorescence measurements were each performed at six different body sites: the volar surfaces of both forearms (arms), dorsal surfaces of both calves (legs), and plantar surfaces of both feet (feet). Within- and between-site agreements were analyzed with concordance correlation coefficients (CCC) and 95% confidence intervals (95% CI), absolute mean differences (±standard deviation), and Bland-Altman limits of agreement.

RESULTS

The agreement between repeat assessments at the same site was almost perfect (CCC [95% CI] ranging from 0.94 [0.91-0.96] for assessments in the right foot to 0.99 [0.99-0.99] for assessments in the left arm). The limits of agreement were narrow within ±0.5 arbitrary units for all sites. The between-site agreement in measurements was poor (CCC < 0.65) with large maximum absolute mean differences (±SD) in arbitrary units (DFU = 3.40 [±2.04]; DMC = 3.15 [±2.45]; HC = 2.72 [±1.83]) and wide limits of agreement.

CONCLUSIONS

Skin autofluorescence measurements can be repeated at the same site with adequate repeatability but measurements at different sites in the same patient have marked differences. The reason for this variation across sites and whether this has any role in diabetes-related complications needs further investigation.

Presentation and outcomes of indigenous Australians with peripheral artery disease

Background

The risk factors for peripheral artery disease (PAD) are more common in Indigenous than non-Indigenous Australians, however the presentation and outcome of PAD in Indigenous Australians has not been previously investigated. The aim of this prospective cohort study was to compare the presenting characteristics and clinical outcome of Indigenous and non-Indigenous Australians with PAD.

Methods

PAD patients were prospectively recruited and followed-up since 2003 from an outpatient vascular clinic in Townsville, Australia. Presenting symptoms and risk factors in Indigenous and non-Indigenous patients were compared using Pearson’s χ2 test and Mann Whitney U test. Kaplan Meier survival analysis and Cox proportional hazard analysis were used to compare the incidence of myocardial infarction (MI), stroke or death (major cardiovascular events) among Indigenous and non-Indigenous patients.

Results

Four hundred and one PAD patients were recruited, of which 16 were Indigenous and 385 were non-Indigenous Australians. Indigenous Australians were younger at entry (median age 63.3 [54.7–67.8] vs 69.6 [63.3–75.4]), more commonly current smokers (56.3% vs 31.4%), and more frequently had insulin-treated diabetes (18.8% vs 5.2%). During a median follow-up of 2.5 years, five and 45 major cardiovascular events were recorded amongst Indigenous and non-Indigenous Australians, respectively. Indigenous Australians were at ~ 5-fold greater risk of major cardiovascular events (adjusted hazard ratio 4.72 [95% confidence intervals 1.41–15.78], p = 0.012) compared to non-Indigenous Australians.

Conclusions

These findings suggest that Indigenous Australians with PAD present at a younger age, have higher rates of smoking and insulin-treated diabetes, and poorer clinical outcomes compared to non-Indigenous Australians.

Risk of major amputation in patients with intermittent claudication undergoing early revascularization

BACKGROUND

Revascularization is being used increasingly for the treatment of intermittent claudication and yet few studies have reported the long-term outcomes of this strategy. The aim of this study was to compare the long-term outcome of patients with intermittent claudication who underwent revascularization compared with a group initially treated without revascularization.

METHODS

Patients with symptoms of intermittent claudication and a diagnosis of peripheral arterial disease were recruited from outpatient clinics at three hospitals in Queensland, Australia. Based on variation in the practices of different vascular specialists, patients were either treated by early revascularization or received initial conservative treatment. Patients were followed in outpatient clinics using linked hospital admission record data. The primary outcome was the requirement for major amputation. Kaplan-Meier curves, Cox regression and competing risks analyses were used to compare major amputation rates.

RESULTS

Some 456 patients were recruited; 178 (39·0 per cent) underwent early revascularization and 278 (61·0 per cent) had initial conservative treatment. Patients were followed for a mean(s.d.) of 5·00(3·37) years. The estimated 5-year major amputation rate was 6·2 and 0·7 per cent in patients undergoing early revascularization and initial conservative treatment respectively (P = 0·003). Early revascularization was associated with an increased requirement for major amputation in models adjusted for other risk factors (relative risk 5·40 to 4·22 in different models).

CONCLUSION

Patients presenting with intermittent claudication who underwent early revascularization appeared to be at higher risk of amputation than those who had initial conservative treatment.

Inositol in the MAnaGemENt of abdominal aortic aneurysm (IMAGEN): study protocol for a randomised controlled trial

Background

An abdominal aortic aneurysm (AAA) is a focal dilation of the abdominal aorta and is associated with a risk of fatal rupture. Experimental studies suggest that myo-inositol may exert beneficial effects on AAAs through favourable changes to biological pathways implicated in AAA pathology. The aim of the Inositol in the MAnaGemENt of abdominal aortic aneurysm (IMAGEN) trial is to assess if myo-inositol will reduce AAA growth.

Methods/design

IMAGEN is a multi-centre, prospective, parallel-group, randomised, double-blind, placebo-controlled trial. A total of 164 participants with an AAA measuring ≥ 30 mm will be randomised to either 2 g of myo-inositol or identical placebo twice daily for 12 months. The primary outcome measure will be AAA growth estimated by increase in total infrarenal aortic volume measured on computed tomographic scans. Secondary outcome measures will include AAA diameter assessed by computed tomography and ultrasound, AAA peak wall stress and peak wall rupture index, serum lipids, circulating AAA biomarkers, circulating RNAs and health-related quality of life. All analysis will be based on the intention-to-treat principle at the time of randomisation. All patients who meet the eligibility criteria, provide written informed consent and are enrolled in the study will be included in the primary analysis, regardless of adherence to dietary allocation.

Discussion

Currently, there is no known medical therapy to limit AAA progression. The IMAGEN trial will be the first randomised trial, to our knowledge, to assess the value of myo-inositol in limiting AAA growth.

Trial registration

Australian New Zealand Clinical Trials Registry, ACTRN12615001209583. Registered on 6 November 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2304-x) contains supplementary material, which is available to authorized users.

Assessment and validation of a novel angiographic scoring system for peripheral artery disease

BACKGROUND

Angiography is used routinely in the assessment of lower-limb arteries, but there are few well validated angiographic scoring systems. The aim of this study was to develop and validate a novel angiographic scoring system for peripheral artery disease.

METHODS

An angiographic scoring system (the ANGIO score) was developed and applied to a sample of patients from a single vascular surgical department who underwent CT angiography of the lower limbs. The reproducibility of the ANGIO score was compared with those of the Bollinger and Trans-Atlantic inter-Society Consensus (TASC) IIb systems in a series of randomly selected patients. Associations between the ANGIO score and lower-limb ischaemia, as measured by the ankle : brachial pressure index (ABPI), and outcome events (major lower-limb amputations and cardiovascular events - myocardial infarction, stroke and cardiovascular death) were assessed.

RESULTS

Some 256 patients undergoing CT angiography were included. The interobserver reproducibility of the ANGIO score was better than that of the other scoring systems examined (κ = 0·90, P = 0·002). There was a negative correlation between the ANGIO score and ABPI (ρ = -0·33, P = 0·008). A higher ANGIO score was associated with an increased risk of major lower-limb amputation (hazard ratio (HR) for highest versus lowest tertile 9·30, 95 per cent c.i. 1·95 to 44·38; P = 0·005) and cardiovascular events (HR 2·73, 1·31 to 5·70; P = 0·007) following adjustment for established risk factors.

CONCLUSION

The ANGIO score provided a reproducible and valid assessment of the severity of lower-limb ischaemia and risk of major amputation and cardiovascular events in these patients with peripheral artery disease.

Efficacy of brief behavioral counselling by allied health professionals to promote physical activity in people with peripheral arterial disease (BIPP): study protocol for a multi-center randomized controlled trial

Background

Physical activity is recommended for people with peripheral arterial disease (PAD), and can improve walking capacity and quality of life; and reduce pain, requirement for surgery and cardiovascular events. This trial will assess the efficacy of a brief behavioral counselling intervention delivered by allied health professionals to improve physical activity in people with PAD.

Methods

This is a multi-center randomised controlled trial in four cities across Australia. Participants (N = 200) will be recruited from specialist vascular clinics, general practitioners and research databases and randomised to either the control or intervention group. Both groups will receive usual medical care, a written PAD management information sheet including advice to walk, and four individualised contacts from a protocol-trained allied health professional over 3 months (weeks 1, 2, 6, 12). The control group will receive four 15-min telephone calls with general discussion about PAD symptoms and health and wellbeing. The intervention group will receive behavioral counselling via two 1-h face-to-face sessions and two 15-min telephone calls. The counselling is based on the 5A framework and will promote interval walking for 3 × 40 min/week. Assessments will be conducted at baseline, and 4, 12 and 24 months by staff blinded to participant allocation. Objectively assessed outcomes include physical activity (primary), sedentary behavior, lower limb body function, walking capacity, cardiorespiratory fitness, event-based claudication index, vascular interventions, clinical events, cardiovascular function, circulating markers, and anthropometric measures. Self-reported outcomes include physical activity and sedentary behavior, walking ability, pain severity, and health-related quality of life. Data will be analysed using an intention-to-treat approach. An economic evaluation will assess whether embedding the intervention into routine care would likely be value for money. A cost-effectiveness analysis will estimate change in cost per change in activity indicators due to the intervention, and a cost-utility analysis will assess change in cost per quality-adjusted life year. A full uncertainty analysis will be undertaken, including a value of information analysis, to evaluate the economic case for further research.

Discussion

This trial will evaluate the efficacy and cost-effectiveness of a brief behavioral counselling intervention for a common cardiovascular disease with significant burden.

Trial registration

ACTRN 12614000592640 Australian New Zealand Clinical Trials Registry. Registration Date 4 June 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3801-7) contains supplementary material, which is available to authorized users.

Lower limb biomechanical characteristics of patients with neuropathic diabetic foot ulcers: the diabetes foot ulcer study protocol

BACKGROUND

Foot ulceration is the main precursor to lower limb amputation in patients with type 2 diabetes worldwide. Biomechanical factors have been implicated in the development of foot ulceration; however the association of these factors to ulcer healing remains less clear. It may be hypothesised that abnormalities in temporal spatial parameters (stride to stride measurements), kinematics (joint movements), kinetics (forces on the lower limb) and plantar pressures (pressure placed on the foot during walking) contribute to foot ulcer healing. The primary aim of this study is to establish the biomechanical characteristics (temporal spatial parameters, kinematics, kinetics and plantar pressures) of patients with plantar neuropathic foot ulcers compared to controls without a history of foot ulcers. The secondary aim is to assess the same biomechanical characteristics in patients with foot ulcers and controls over-time to assess whether these characteristics remain the same or change throughout ulcer healing.

METHODS/DESIGN

The design is a case-control study nested in a six-month longitudinal study. Cases will be participants with active plantar neuropathic foot ulcers (DFU group). Controls will consist of patients with type 2 diabetes (DMC group) and healthy participants (HC group) with no history of foot ulceration. Standardised gait and plantar pressure protocols will be used to collect biomechanical data at baseline, three and six months. Descriptive variables and primary and secondary outcome variables will be compared between the three groups at baseline and follow-up.

DISCUSSION

It is anticipated that the findings from this longitudinal study will provide important information regarding the biomechanical characteristic of type 2 diabetes patients with neuropathic foot ulcers. We hypothesise that people with foot ulcers will demonstrate a significantly compromised gait pattern (reduced temporal spatial parameters, kinematics and kinetics) at base line and then throughout the follow-up period compared to controls. The study may provide evidence for the design of gait-retraining, neuro-muscular conditioning and other approaches to off-load the limbs of those with foot ulcers in order to reduce the mechanical loading on the foot during gait and promote ulcer healing.

Association of impaired fasting glucose, diabetes and their management with the presentation and outcome of peripheral artery disease: a cohort study

Background

Pre-diabetes and untreated diabetes are common in patients with peripheral artery disease however their impact on outcome has not been evaluated. We examined the association of impaired fasting glucose, diabetes and their treatment with the presentation, mortality and requirement for intervention in peripheral artery disease patients.

Methods

We prospectively recruited 1637 patients with peripheral artery disease, measured fasting glucose, recorded medications for diabetes and categorised them by diabetes status. Patients were followed for a median of 1.7 years.

Results

At entry 22.7% patients were receiving treatment for type 2 diabetes by oral hypoglycaemics alone (18.1%) or insulin (4.6%). 9.2% patients had non-medicated diabetes. 28.1% of patients had impaired fasting glucose (5.6-6.9 mM). Patients with non-medicated diabetes had increased mortality and requirement for peripheral artery intervention (hazards ratio 1.62 and 1.31 respectively). Patients with diabetes prescribed insulin had increased mortality (hazard ratio 1.97). Patients with impaired fasting glucose or diabetes prescribed oral hypoglycaemics only had similar outcomes to patients with no diabetes.

Conclusions

Non-medicated diabetes is common in peripheral artery disease patients and associated with poor outcomes. Impaired fasting glucose is also common but does not increase intermediate term complications. Peripheral artery disease patients with diabetes requiring insulin are at high risk of intermediate term mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-014-0147-2) contains supplementary material, which is available to authorized users.