Increased arterial stiffness in remote Indigenous Australians with high risk of cardiovascular disease

Subclinical vascular disease in patients with diabetes is associated with insulin resistance

Patients with diabetes experience increased cardiovascular risk that is not fully explained by deficient glycemic control or traditional cardiovascular risk factors such as smoking and hypercholesterolemia. Asymptomatic patients with diabetes show structural and functional vascular damage that includes impaired vasodilation, arterial stiffness, increased intima-media thickness and calcification of the arterial wall. Subclinical vascular injury associated with diabetes predicts subsequent manifestations of cardiovascular disease, such as ischemic heart disease, peripheral artery disease and stroke. Noninvasive detection of subclinical vascular disease is commonly used to estimate cardiovascular risk associated to diabetes. Longitudinal studies in normotensive subjects show that arterial stiffness at baseline is associated with a greater risk for future hypertension independently of established risk factors. In patients with type 2 diabetes, vascular disease begins to develop during the latent phase of insulin resistance, long before the clinical diagnosis of diabetes. In contrast, patients with type 1 diabetes do not manifest vascular injury when they are first diagnosed due to insulin deficiency, as they lack the preceding period of insulin resistance. These findings suggest that insulin resistance plays an important role in the development of early vascular disease associated with diabetes. Cross-sectional and prospective studies confirm that insulin resistance is associated with subclinical vascular injury in patients with diabetes, independently of standard cardiovascular risk factors. Asymptomatic vascular disease associated with diabetes begins to occur early in life having been documented in children and adolescents. Insulin resistance should be considered a therapeutic target in order to prevent the vascular complications associated with diabetes.

Insulin resistance is associated with subclinical vascular disease in humans

Insulin resistance is associated with subclinical vascular disease that is not justified by conventional cardiovascular risk factors, such as smoking or hypercholesterolemia. Vascular injury associated to insulin resistance involves functional and structural damage to the arterial wall that includes impaired vasodilation in response to chemical mediators, reduced distensibility of the arterial wall (arterial stiffness), vascular calcification, and increased thickness of the arterial wall. Vascular dysfunction associated to insulin resistance is present in asymptomatic subjects and predisposes to cardiovascular diseases, such as heart failure, ischemic heart disease, stroke, and peripheral vascular disease. Structural and functional vascular disease associated to insulin resistance is highly predictive of cardiovascular morbidity and mortality. Its pathogenic mechanisms remain undefined. Prospective studies have demonstrated that animal protein consumption increases the risk of developing cardiovascular disease and predisposes to type 2 diabetes (T2D) whereas vegetable protein intake has the opposite effect. Vascular disease linked to insulin resistance begins to occur early in life. Children and adolescents with insulin resistance show an injured arterial system compared with youth free of insulin resistance, suggesting that insulin resistance plays a crucial role in the development of initial vascular damage. Prevention of the vascular dysfunction related to insulin resistance should begin early in life. Before the clinical onset of T2D, asymptomatic subjects endure a long period of time characterized by insulin resistance. Latent vascular dysfunction begins to develop during this phase, so that patients with T2D are at increased cardiovascular risk long before the diagnosis of the disease.

Cardiovascular target organ damage could have been detected in sustained pediatric hypertension

The aim of this study was to assess sustained hypertension in children and its impact on cardiovascular target organ damage (TOD). Blood pressure (BP) was measured in children in Beijing in 2009. Primary hypertension was diagnosed based on three separate visits. Hypertensive children and normotensive children were followed up in 2011. According to these evaluations, three groups were defined: sustained hypertension, non-sustained hypertension and normotensive. Cardiovascular TOD and metabolic disorders were evaluated using pulse-wave velocity (PWV), carotid intima-media thickness (cIMT), and assessments of left ventricular structure and kidney function. A total of 3032 children aged 9-15 years participated in this survey, of whom 128 were diagnosed with hypertension after three separate BP measurements. Eighty out of 128 (62.5%) hypertensive and 158 normotensive children were available for follow-up in 2011. Forty-eight children were defined as having sustained hypertension, 38 as non-sustained hypertension and 152 as normotensive. Mean levels of brachial-ankle PWV (baPWV), left ventricular mass, left ventricular mass index (LVMI) and cIMT were significantly different between the three groups (p < 0.01). Compared to normotensives, the odds ratios and 95% confidence intervals for elevated LVM and cIMT were 5.27 (1.57-17.66) and 2.88 (1.03-8.09) in the non-sustained hypertensive group, and 3.28 (1.00-10.74) and 7.25 (2.69-19.58) in the sustained hypertensive group. The children with sustained hypertension have the highest risk of developing arterial stiffness, left ventricular hypertrophy and early blood vessel endothelium damage. The indices of cIMT, LVMI and PWV were useful to identify children at high risk of cardiovascular TOD.

Effect of periodontal therapy on arterial structure and function among aboriginal australians: a randomized, controlled trial

Observational studies and nonrandomized trials support an association between periodontal disease and atherosclerotic vascular disease. Both diseases occur frequently in Aboriginal Australians. We hypothesized that nonsurgical periodontal therapy would improve measures of arterial function and structure that are subclinical indicators of atherosclerotic vascular disease. This parallel-group, randomized, open label clinical trial enrolled 273 Aboriginal Australians aged ≥18 years with periodontitis. Intervention participants received full-mouth periodontal scaling during a single visit, whereas controls received no treatment. Prespecified primary end points measured 12-month change in carotid intima-media thickness, an indicator of arterial structure, and 3- and 12-month change in pulse wave velocity, an indicator of arterial function. ANCOVA used complete case data to evaluate treatment group differences. End points could be calculated for 169 participants with follow-up data at 3 months and 168 participants at 12 months. Intima-media thickness decreased significantly after 12 months in the intervention group (mean reduction=-0.023 [95% confidence interval {CI}, -0.038 to -0.008] mm) but not in the control group (mean increase=0.002 [95% CI, -0.017 to 0.022] mm). The difference in intima-media thickness change between treatment groups was statistically significant (-0.026 [95% CI, -0.048 to -0.003] mm; P=0.03). In contrast, there were no significant differences between treatment groups in pulse wave velocity at 3 months (mean difference, 0.06 [95% CI, -0.17 to 0.29] m/s; P=0.594) or 12 months (mean difference, 0.21 [95% CI, -0.01 to 0.43] m/s; P=0.062). Periodontal therapy reduced subclinical arterial thickness but not function in Aboriginal Australians with periodontal disease, suggesting periodontal disease and atherosclerosis are significantly associated.

Is obesity predictive of cardiovascular dysfunction independent of cardiovascular risk factors?

INTRODUCTION

Obesity is thought to exert detrimental effects on the cardiovascular (CV) system. However, this relationship is impacted by the co-occurrence of CV risk factors, type 2 diabetes (T2DM) and overt disease. We examined the relationships between obesity, assessed by body mass index (BMI) and waist circumference (WC), and CV function in 102 subjects without overt CV disease. We hypothesized that obesity would be independently predictive of CV remodeling and functional differences, especially at peak exercise.

METHODS

Brachial (bSBP) and central (cSBP) systolic pressure, carotid-to-femoral pulse wave velocity (PWVcf) augmentation index (AGI; by SphygmoCor), and carotid remodeling (B-mode ultrasound) were examined at rest. Further, peak exercise cardiac imaging (Doppler ultrasound) was performed to measure the coupling between the heart and arterial system.

RESULTS

In backward elimination regression models, accounting for CV risk factors, neither BMI nor WC were predictors of carotid thickness or PWVcf; rather age, triglycerides and hypertension were the main determinants. However, BMI and WC predicted carotid cross-sectional area and lumen diameter. When examining the relationship between body size and SBP, BMI (β=0.32) and WC (β=0.25) were predictors of bSBP (P<0.05), whereas, BMI was the only predictor of cSBP (β=0.22, P<0.05) indicating a differential relationship between cSBP, bSBP and body size. Further, BMI (β=-0.26) and WC (β=-0.27) were independent predictors of AGI (P<0.05). As for resting cardiac diastolic function, WC seemed to be a better predictor than BMI. However, both BMI and WC were inversely and independently related to arterial-elastance (net arterial load) and end-systolic elastance (cardiac contractility) at rest and peak exercise.

CONCLUSION

These findings illustrate that obesity, without T2DM and overt CV disease, and after accounting for CV risk factors, is susceptible to pathophysiological adaptations that may predispose individuals to an increased risk of CV events.

Serum uric acid is associated with arterial stiffness in men with newly diagnosed type 2 diabetes mellitus

BACKGROUND

Increased serum uric acid levels and vascular atherosclerosis are very common in diabetes. However, few studies focused on the relationship between serum uric acid and aortic or peripheral arterial stiffness in newly diagnosed diabetic patients. This study investigated the association between serum uric acid levels and carotid-femoral pulse wave velocity (cfPWV) or carotid-radial (cr) PWV in male patients with newly diagnosed type 2 diabetes mellitus (T2DM).

METHODS

106 male patients with newly diagnosed T2DM were recruited. cfPWV and crPWV as well as anthropometric parameters, blood pressure, serum uric acid, blood glucose, fasting insulin, C-reactive protein and blood lipids were measured.

RESULTS

The subjects were divided into low uric acid (UA) subgroup and high UA subgroup according to uric acid median. cfPWV and crPWV were significantly higher in high UA subgroup. Serum uric acid significantly correlated with cfPWV (r = 0.533, P < 0.001), crPWV (r = 0.334, P = 0.001), waist circumference (r = 0.350, P < 0.001), waist-to-hip ratio (r = 0.254, P = 0.009), fasting insulin (r = 0.432, P < 0.001), HOMA-IR (r = 0.173, P = 0.042), fasting blood glucose (r = -0.271, P = 0.005), haemoglobin A1c (r = -0.202, P = 0.038), and HDL-cholesterol (r = -0.267, P = 0.006) after correction for age. Stepwise multiple regressions showed that the independent determinants of cfPWV were serum uric acid, age, C-reactive protein, HDL-cholesterol, and smoking status. And the independent determinants of crPWV were serum uric acid, age, diastolic blood pressure, and HDL-cholesterol.

CONCLUSIONS

Serum uric acid is significantly associated with increased aortic and peripheral arterial stiffness in men with T2DM at the early stage.

Pneumococcus in Aboriginal and Torres Strait Islanders: the role of Aboriginal Health Workers and implications for nursing practice

Abstract Background: Pneumonia is a common cause of hospitalization in Aboriginal and Torres Strait Islander men and women. Aim: This article seeks to describe the importance of immunizing against pneumonia in Aboriginal Australians and suggest strategies for screening and follow-up. Method: An integrative literature review, using both published and grey literature was undertaken to identify methods of screening and surveillance strategies for pneumococcus. Results: The literature was summarized under the following themes: pneumococcal disease; prevention strategies; access to care; improving access to vaccinations; culturally competent interventions and the role of Aboriginal health professionals. Conclusion: Community controlled conditions and the role of the Aboriginal Health Workers are seen as critical to reducing health disparities. Nurses can play a critical role in bridging the gap between mainstream and community controlled organizations. Working to increase the numbers of Aboriginal health professionals is a critical step in improving health outcomes for Aboriginal and Torres Strait Islander peoples.

Closing the Gaps: competing estimates of Indigenous Australian life expectancy in the scientific literature

OBJECTIVE

Closing the gap in life expectancy between Indigenous and other Australians within a generation is central to national Indigenous reform policy (Closing the Gap). Over time, various methods of estimating Indigenous life expectancy and with that, the life expectancy gap, have been adopted with differing, albeit non-comparable results. We present data on the extent of the gap and elucidate the pattern of use and interpretations of the different estimates of the gap, between 2007 and 2012.

METHODS

An extensive search was conducted for all peer-reviewed health publications citing estimates of and/or discussing the life expectancy of Indigenous Australians, for the period 2007-2012.

RESULTS

Five predominant patterns of citation of the gap estimates were identified: 20 years, 17 years, 15-20 years, 13 years, and 11.5 years for males and 9.7 years for females. Some authors misinterpret the most recent estimates as reflecting improvement from the 17-year figure, rather than the result of different methods of estimation. Support for the direct methods used to calculate Indigenous life expectancy is indicated.

CONCLUSIONS AND IMPLICATIONS

A specific estimate of the life expectancy gap has not been established among stakeholders in Indigenous health. Agreement on the magnitude of the gap is arguably needed in order to evaluate strategies aimed at improving health outcomes for Indigenous Australians. Moreover, measuring progress towards 'closing the gap' depends on the availability of comparable estimates, using the same techniques of measurement to assess changes over time.

Continuing disparities in cardiovascular risk factors and complications between aboriginal and Anglo-Celt Australians with type 2 diabetes: the Fremantle Diabetes Study

OBJECTIVE

To determine whether disparities in the nature and management of type 2 diabetes persist between Aboriginal and the majority Anglo-Celt patients in an urban Australian community.

RESEARCH DESIGN AND METHODS

Baseline data from the observational Fremantle Diabetes Study collected from 1993 to 1996 (phase I) and from 2008 to 2011 (phase II) were analyzed. Patients characterized as Aboriginal or Anglo-Celt by self-report and supporting data underwent comprehensive assessment, including questionnaires, examination, and biochemical testing in a single laboratory. Generalized linear modeling with age/sex adjustment was used to examine differences in changes in variables in the two groups between phases I and II.

RESULTS

The indigenous participants were younger at entry and at diabetes diagnosis than the Anglo-Celt participants in both phases. They were also less likely to be educated beyond primary level and were more likely to be smokers. HbA(1c) decreased in both groups over time (Aboriginal median 9.6% [interquartile range 7.8-10.7%] to 8.4% [6.6-10.6%] vs. Anglo-Celt median 7.1% [6.2-8.4%] to 6.7% [6.2-7.5%]), but the gap persisted (P = 0.65 for difference between phases I and II by ethnic group). Aboriginal patients were more likely to have microvascular disease in both phases. The prevalence of peripheral arterial disease (ankle-brachial index ≤0.90 or lower-extremity amputation) increased in Aboriginal but decreased in Anglo-Celt participants (15.8-29.7 vs. 30.7-21.5%; P = 0.055).

CONCLUSIONS

Diabetes management has improved for Aboriginal and Anglo-Celt Australian patients, but disparities in cardiovascular risk factors and complications persist.

Reference value of brachial-ankle pulse wave velocity for the eastern Chinese population and potential influencing factors

The present study was conducted to obtain reference values for brachial-ankle pulse wave velocity (baPWV) and to evaluate influencing factors of baPWV according to gender. Using automatic devices, baPWV was measured simultaneously in 2095 subjects. A total of 647 healthy subjects, none of whom presented atherosclerotic risk factors, were analyzed in the present study. Two different statistical methods were used to obtain reference values for baPWV according to subject gender and age. The association between baPWV value and gender, as well as other features, were analyzed. For male subjects, multiple stepwise analysis showed that age, systolic blood pressure (SBP), heart rate (HR), and plasma levels of triglycerides (TG) were independent predictors of baPWV. For female subjects, age, SBP, HR, and plasma levels of uric acid (UA) were independent predictors of baPWV. In male subjects, the upper limits of baPWV values were 1497.43/1425.00, 1518.67/1513.25, 1715.97/1726.50, 1925.20/1971.90, and 2310.18/2115.00 cm/s, obtained using two different statistical methods for the age ranges of 30-39, 40-49, 50-59, 60-69, and 70 and older, respectively. For females, the upper limits of baPWV values were 1426.70/1411.13, 1559.15/1498.95, 1733.50/1739.00, 1958.63/1973.78, and 2720.80/2577.00 cm/s for the age ranges of 30-39, 40-49, 50-59, 60-69, and 70 and older, respectively. Aging is the most important influencing factor for baPWV value and its effect is more prominent in females. The reference values of baPWV according to age and gender may be useful for the clinical diagnosis and preventive therapy of cardiovascular diseases.

Abdominal obesity and other risk factors largely explain the high CRP in indigenous Australians relative to the general population, but not gender differences: a cross-sectional study

BACKGROUND

Previous studies reported high C-reactive protein (CRP) levels in Indigenous Australians, which may contribute to their high risk of cardiovascular disease. We compared CRP levels in Indigenous Australians and the general population, accounting for obesity and other risk factors.

METHODS

Cross-sectional study of CRP and risk factors (weight, height, waist and hip circumferences, blood pressure, lipids, blood glucose, and smoking status) in population-based samples from the Diabetes and Related conditions in Urban Indigenous people in the Darwin region (DRUID) study, and the Australian Diabetes, Obesity and Lifestyle study (AusDiab) follow-up.

RESULTS

CRP concentrations were higher in women than men and in DRUID than AusDiab. After multivariate adjustment, including waist circumference, the odds of high CRP (>3.0 mg/L) in DRUID relative to AusDiab were no longer statistically significant, but elevated CRP was still more likely in women than men. After adjusting for BMI (instead of waist circumference) the odds for elevated CRP in DRUID participants were still higher relative to AusDiab participants among women, but not men. Lower HDL cholesterol, impaired glucose tolerance (IGT), and higher diastolic blood pressure were associated with having a high CRP in both men and women, while current smoking was associated with high CRP in men but not women.

CONCLUSIONS

High concentrations of CRP in Indigenous participants were largely explained by other risk factors, in particular abdominal obesity. Irrespective of its independence as a risk factor, or its aetiological association with coronary heart disease (CHD), the high CRP levels in urban Indigenous women are likely to reflect increased vascular and metabolic risk. The significance of elevated CRP in Indigenous Australians should be investigated in future longitudinal studies.

The metabolic syndrome and its traits as risk factors for subclinical atherosclerosis

CONTEXT AND OBJECTIVE

The metabolic syndrome (MetS) indicates an increased cardiovascular risk. The objective of the present study was to determine the impact of the MetS and its individual traits on subclinical atherosclerosis, as measured with six noninvasive measurements of atherosclerosis (NIMA) in a 50- to 70-yr-old Dutch population-based cohort. Furthermore, we determined the impact of three different definitions of the MetS.

DESIGN

We performed NIMA in 1517 participants of the Nijmegen Biomedical Study. The MetS was defined by definitions of the National Cholesterol Education Program, International Diabetes Federation, and the World Health Organization.

RESULTS

Participants with the MetS (National Cholesterol Education Program) were characterized by increased subclinical atherosclerosis compared with participants without any trait of the MetS, as reflected by lower ankle-brachial index at rest [percent change (95% confidence interval), M: -5.2% (-9; -1), F: -3.1% (-6; -1)] and after exercise [M: -7.7% (-17;+2), F: -6.6% (-11; -2)], higher augmentation index [M: +4.8% (+3; +7), F: +1.9% (+4; +18)], increased pulse wave velocity [M: +22.8% (+15;+32), F: +20.5% (+14; +28)], increased intima-media thickness [M: +9.3% (+5; +13), F: +6.9% (+3; +11)], and thicker plaques [M: +17.6% (-2; +41), F: +26.6% (+5; +53)]. Most intriguingly, the number of traits was strongly associated with the severity of subclinical atherosclerosis because all NIMA gradually deteriorated with increasing number of traits present; NIMA were already deteriorated when one or two traits were present and further deteriorated when four or five traits of the MetS were present. Similar result were found when International Diabetes Federation and World Health Organization definitions of the MetS were used.

CONCLUSIONS

For cardiovascular risk prediction, it is more important to take into account the presence of each individual trait and the number of traits of the MetS than to diagnose the presence of the MetS.

Associations between augmentation index and severity of atheroma or aortic stiffness of the descending thoracic aorta by transesophageal echocardiography

BACKGROUND

Although the aortic augmentation index (AI) is an attractive tool as an index of the vascular system, the association between radial AI or brachial-ankle pulse wave velocity (PWV) and severity of atheroma or arterial stiffness of the morphological central artery is unclear.

METHODS AND RESULTS

Severity of atheroma and aortic stiffness of the descending thoracic aorta (DTA) by transesophageal echography in 96 patients with paroxysmal atrial fibrillation was assessed. The relationship between radial AI or brachial-ankle PWV and atherosclerotic lesions was also investigated. The DTA was divided into 3 equal longitudinal portions, and the atheromatous lesions of each portion of the DTA were scored according to their character and extension. Instantaneous dimensional changes in the DTA was measured, and the aortic stiffness index beta was calculated. Radial AI was significantly correlated with age, plasma low-density lipoprotein-cholesterol concentrations, systolic blood pressure, pulse pressure, the mean atheromatous score and the mean aortic stiffness index. However, brachial-ankle PWV was not associated with central arterial stiffness. Multivariate logistic regression analysis showed that radial AI was most closely correlated with the mean atheromatous score.

CONCLUSIONS

Radial AI might be a novel tool for determining the severity of central aortic atheromatous lesions.

Arterial stiffness indices in healthy volunteers using non-invasive digital photoplethysmography

BACKGROUND

Increased arterial stiffness is a marker of cardiovascular damage, even in the absence of clinically apparent disease. It is likely to become an important clinical tool in cardiovascular risk assessment.

AIMS AND METHODS

We studied a group of healthy subjects and measured their arterial stiffness by digital photoplethysmography. We aimed to obtain a range of arterial stiffness values, and investigated the influence of age, gender, race, body mass index, fasting lipids and haemodynamic factors.

RESULTS

One hundred and fifty-two healthy subjects, aged between 18 and 67 years, on no medications and with no significant medical illnesses were recruited. The population was predominantly Caucasian (n = 112). Two measures of arterial stiffness were obtained: stiffness index (SI), a measure of large arterial stiffness, and reflection index (RI), a measure of small to medium-sized arterial stiffness. SI and RI were significantly correlated with age, total cholesterol, low-density lipoprotein-cholesterol, heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP). Race was a significant independent predictor of SI.

CONCLUSION

Digital photoplethysmography is a portable, operator-independent, reproducible and simple method of measuring arterial stiffness. Ranges of normality of arterial stiffness will depend on the individual's age, race, lipid levels, HR and blood pressure.

Impact of dyslipidaemia on arterial structure and function in urban indigenous Australians

BACKGROUND

Premature cardiovascular disease (CDV) is highly prevalent in urban Indigenous Australians. We studied arterial structure and function in 144 volunteers aged 15-66 years to assess the role of dyslipidaemia and other traditional vascular risk factors on cardiovascular risk in young and older urban Indigenous Australians.

METHODS

We assessed carotid intima-media thickness (CIMT) by high-resolution B-mode ultrasound imaging of the common carotid artery and peripheral wave reflection using applanation tonometry to obtain the aortic augmentation index (AI) in Indigenous Australian participants of the Darwin Region Urban Indigenous Diabetes (DRUID) study.

RESULTS

Participants aged 15-24 years demonstrated fewer cardiovascular risk factors than the older group (25-66 years) and predictors of CIMT and AI differed between younger and older groups. CIMT was higher in the older group (0.67mm vs. 0.61mm, p=0.004) and in those with diabetes (0.81mm vs. 0.67mm, p<0.001). AI was higher in the older group (24% vs. 0%, p<0.001), but was not affected by diabetes status. On multivariate regression analysis, low HDL-cholesterol was the only independent predictor of CIMT in the younger group; triglycerides, heart rate (inverse) and height (inverse) were independent predictors of AI in the same group.

CONCLUSION

Dyslipidaemia (low HDL-cholesterol or elevated triglycerides) is independently associated with non-invasive measures of cardiovascular disease in a relatively healthy and young subgroup of this high-risk population. We propose that triglycerides and low HDL-cholesterol may represent the most useful commonly measured clinical indicators of cardiovascular risk in young, urban Indigenous Australians.