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G C Leng

Publications and source records attributed to G C Leng.

34 records · Page 2Linked to original sources
PubMed1996

Use of ankle brachial pressure index to predict cardiovascular events and death: a cohort study.

OBJECTIVE: To determine whether a low ankle brachial pressure index is associated with an increased risk of cardiovascular events and death, and whether the prediction of such events could be improved by including this index. DESIGN: Cohort study. SETTING: 11 practices in Edinburgh, Scotland. SUBJECTS: 1592 men and women aged 55-74 years selected at random from the age-sex registers of 11 general practices and followed up for 5 years. MAIN OUTCOME MEASURES: Incidence of fatal and non-fatal cardiovascular events and all cause mortality. RESULTS: At baseline 90 (5.7%) of subjects had an ankle brachial pressure index < or = 0.7, 288 (18.2%) had an index < or = 0.9, and 566 (35.6%) < or = 1.0. After five years subjects with an index < or = 0.9 at baseline had an increased risk of non-fatal myocardial infarction (relative risk 1.38, 95% confidence interval 0.88 to 2.16), stroke (1.98, 1.05 to 3.77), cardiovascular death (1.85, 1.15 to 2.97), and all cause mortality (1.58, 1.14 to 2.18) after adjustment for age, sex, coronary disease, and diabetes at baseline. The ability to predict subsequent events was greatly increased by combining the index with other risk factors--for example, hypertensive smokers with normal cholesterol concentrations had a positive predictive value of 25.0%, increasing to 43.8% in subjects with a low index and decreasing to 15.6% in those with a normal index. CONCLUSION: The ankle brachial pressure index is a good predictor of subsequent cardiovascular events, and improves on predictions by conventional risk factors alone. It is simple and accurate and could be included in routine screening of cardiovascular status.

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PubMed1996

Incidence, natural history and cardiovascular events in symptomatic and asymptomatic peripheral arterial disease in the general population.

BACKGROUND: Intermittent claudication is associated with a poor prognosis, but less is known of the risks associated with asymptomatic peripheral arterial disease. The aims of this study were to determine the incidence and natural history of claudication, and the incidence of cardiovascular events in symptomatic and asymptomatic peripheral arterial disease. METHODS: In 1988, 1592 subjects aged 55-74 years were selected randomly from the age-sex register of 10 general practices in Edinburgh, Scotland. The presence of peripheral arterial disease was determined by the World Health Organization questionnaire on intermittent claudication, the ankle brachial pressure index and a reactive hyperaemia test. This cohort was followed prospectively over 5 years for subsequent cardiovascular events and death. RESULTS: One hundred and sixteen new cases of claudication were identified (incidence density 15.5 per 1000 person-years). Of those with claudication at baseline, 28.8% and still had pain after 5 years, 8.2% underwent vascular surgery or amputation, and 1.4% developed leg ulceration. Claudicants had a significantly increased risk of developing angina compared with normals (RR: 2.31, 95% CI: 1.04-5.10), and asymptomatic subjects had a slightly increased risk of myocardial infarction and stroke. Deaths from cardiovascular disease were more likely in both claudicants (RR: 2.67, 95% CI: 1.34-5.29) and subjects with major (RR: 2.08, 95% CI: 1.13-3.83) or minor asymptomatic disease (RR: 1.74, 95% CI: 1.09-2.76). Subjects with major asymptomatic disease also had an increased risk of non-cardiovascular death (RR: 2.19, 95% CI: 1.33-3.59), and therefore had the highest overall risk of death (RR: 2.44, 95% CI: 1.59-3.74). CONCLUSIONS: Subjects with asymptomatic peripheral arterial disease appear to have the same increased risk of cardiovascular events and death found in claudicants.

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PubMed1995

The relationship between cigarette smoking and cardiovascular risk factors in peripheral arterial disease compared with ischaemic heart disease. The Edinburgh Artery Study.

Cigarette smoking is probably the most important risk factor for the development of peripheral arterial disease, but it may be less important in the aetiology of ischaemic heart disease. The objectives of this study were to determine whether any other cardiovascular risk factors showed a significant interaction with cigarette smoking which would explain the greater association between smoking and peripheral atherosclerosis. One thousand five hundred and ninety-two subjects aged 55-74 years were selected randomly from the age-sex registers of 10 general practices in Edinburgh, Scotland. The presence of peripheral arterial disease was determined by the World Health Organisation questionnaire on intermittent claudication, the ankle brachial pressure index and a reactive hyperaemia test. Heart disease was identified by the patients' recall of a doctor diagnosis of angina or myocardial infarction. There were 131 subjects with peripheral arterial disease but no ischaemic heart disease, and 169 with heart disease without peripheral disease. Significantly more smokers occurred in the peripheral than the heart disease group (P <0.01), and in current smokers the age and sex adjusted odds ratio were highly significant for peripheral arterial disease (odds ratio 5.09, 95% confidence interval 2.97-8.72, P<0.001), but not for heart disease (odds ratio 1.72, 95% confidence interval 0.98-2.33, P>0.05). Subjects with lower limb disease also had higher systolic pressures (P<0.001), serum high density lipoprotein cholesterol (P<0.01) and plasma fibrinogen (P<0.05). On logistic regression, adjusting for a range of individual risk factors had no significant impact on the effect of smoking. Plasma fibrinogen produced the biggest reduction in odds ratio (4.23, 95% confidence interval 2.44-7.35, in current smokers with peripheral arterial disease). Therefore the stronger association between smoking and peripheral arterial disease than ischaemic heart disease does not appear to be influenced by the other risk factors examined here, and must be explained by some other mechanism.

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PubMed1994

Relationship between plasma essential fatty acids and smoking, serum lipids, blood pressure and haemostatic and rheological factors.

We aimed to determine whether levels of plasma fatty acids are correlated with other potential risk factors for cardiovascular disease, using a sample of patients from a cross-sectional survey of the general population, in the City of Edinburgh. 306 men and women aged 55-74 years of whom half had clinical evidence of arterial disease were tested. The main outcome measures were plasma fatty acids and potential risk factors for cardiovascular disease (age, sex, smoking, blood pressure, serum cholesterol, HDL cholesterol (HDL-C), triglycerides (TGs), lipid peroxides (LPx), plasma fibrinogen, von-Willebrand factor (vWf), beta-thromboglobulin (beta TG), cross-linked fibrin degradation products (FIBDP) and plasminogen activator inhibitor PAI). High levels of several known risk factors for cardiovascular diseases were associated with low levels of certain essential fatty acids. Eicosapentaenoic (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) were negatively associated with smoking and TG levels. High levels of certain haemostatic factors, including plasma fibrinogen, blood viscosity and LPx were also associated with low levels of EPA, DHA, AA and HDL-C. In conclusion, plasma fatty acids show strong correlations with many potential risk factors for cardiovascular disease, emphasising their possible importance in pathogenesis.

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PubMed1994

Plasma essential fatty acids, cigarette smoking, and dietary antioxidants in peripheral arterial disease. A population-based case-control study.

The aim of this study was to determine the levels of plasma fatty acids in patients with peripheral arterial disease and in control subjects and to identify whether any risks of disease related to these differences were influenced by smoking and antioxidant intake. A random sample of 1592 men and women aged 55 to 74 years was selected from the general population (the Edinburgh Artery Study), from which 153 cases of peripheral arterial disease were identified by the presence of intermittent claudication and low ankle systolic pressures at rest and during reactive hyperemia; these were matched by age and sex to 153 control subjects with no evidence of cardiovascular disease. In 113 case and 122 control subjects, fatty acid levels were measured in three plasma fractions (triglyceride, cholesteryl ester, and phospholipid), and smoking habits and dietary antioxidant intake were determined by questionnaire. Arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid (DPA/n-3) were significantly lower in the cases than controls (P < .01). More case than control subjects were current or exsmokers (86% versus 50%; P < .001), and the case subjects had lower vitamin C intake (64.8 mg versus 71.1 mg; P < .05). By logistic regression adjustment for smoking and vitamin C intake, only DPA/n-3 (odds ratio, 0.19; P < .01) and arachidonic acid (odds ratio, 0.44; P < .05) remained significantly related to disease; only DPA/n-3 reduced the risk associated with smoking. We conclude that in subjects with peripheral arterial disease compared with healthy control subjects, the largest differences occurred in fatty acids of the n-3 series, particularly DPA/n-3.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1993

Reactive hyperemia test in a random sample of the general population.

PURPOSE: The purpose of this article is to determine the performance of a reactive hyperemia test in the general population in terms of validity, increase in case identification, and test refusal; and to identify differences between the two major ways of expressing the results (the postocclusive ankle index and the percentage change in ankle systolic pressure). METHODS: Changes in ankle pressures were measured during reactive hyperemia in 1460 men and women aged 55 to 74 years, who were randomly sampled in the Edinburgh Artery Study. The validity of the test was determined in 91 cases identified by the presence of intermittent claudication and a low resting ankle pressure and in 91 controls matched by age and sex. RESULTS: The mean postocclusive ankle index was 0.98 (SD 0.20), and the mean drop in ankle pressure was 9.89% (SD 12.79%). In examining the validity of the test, differences occurred in the two ways of expressing the results: the postocclusive ankle index was 90% sensitive and 97% specific and the percentage drop in ankle pressure was 52% sensitive and 86% specific in detecting disease. The postocclusive ankle index increased the overall identification of cases in the Edinburgh Artery Study from 6.5% to 11.5%, but the percentage drop in ankle pressure increased identification to only 9.5%. Eight percent of subjects refused the test because of discomfort; this group contained more women, more elderly, and more obese subjects. CONCLUSIONS: The reactive hyperemia test is an appropriate test to use in the general population. The results are more accurate when expressed as the postocclusive ankle index rather than the percentage drop in ankle pressure.

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PubMed1993

Physical activity and risk of peripheral arterial disease in the general population: Edinburgh Artery Study.

STUDY OBJECTIVE: To determine associations between physical activity at age 35-45 years with peripheral arterial disease and cardiovascular risk factors at age 55-74 years. DESIGN: Cross sectional survey of the general population--Edinburgh Artery Study. The presence of peripheral arterial disease was determined using the WHO/Rose questionnaire on intermittent claudication, and the ankle brachial pressure index at rest and during reactive hyperaemia. Levels of physical activity undertaken at the time of the survey and at the times the subjects were aged 35-45 years were measured by self administered recall questionnaire. SETTING: City of Edinburgh, Scotland. PARTICIPANTS: Altogether 1592 men and women aged 55 to 74 years, selected from the age-sex registers of 10 general practices spread geographically and socioeconomically throughout the city. MAIN RESULTS: Participation in moderate or strenuous activity when aged 35-45 years was reported by 66% of men and 40% of women. In men, but not in women, less peripheral arterial disease (measured by an increasing trend in the ankle brachial pressure index) was found with increasing amounts of exercise at age 35-45 years (p < 0.001). Higher levels of exercise at age 35-45 years were associated with lower blood viscosity (p < 0.05) and plasma fibrinogen levels (p < 0.05) in men and women aged 55-74 years, and also with higher current alcohol intake (p < 0.001) and high density lipoprotein cholesterol concentrations (p < 0.01) in women aged 55-74 years. After adjustment for age, sex, life-time smoking, social class, body mass index, and alcohol intake, the association between leisure activity aged 35-45 years and the ankle brachial pressure index aged 55-74 years remained highly significant in men who had at some time smoked (p < 0.001) but not in men or women who had never smoked (p > 0.05). CONCLUSION: The risk of peripheral arterial disease, particularly among male smokers, is inversely related to previous physical activity in early middle age, suggesting a protective effect of exercise.

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PubMed1993

Accuracy and reproducibility of duplex ultrasonography in grading femoropopliteal stenoses.

PURPOSE: The aim of this study was to determine the accuracy of Doppler waveform characteristics in grading femoropopliteal stenoses and to determine the interobserver and intraobserver reproducibility of measuring the same waveform characteristics. METHODS: Thirty patients with isolated areas of stenosis found by arteriography were evaluated by color duplex sonography. Each patient underwent scanning by two observers on two separate occasions. Each observer was blind to the other's results. Doppler spectra were recorded in areas where color change suggested the highest velocity and also at the nearest normal proximal area. Peak systolic velocity, spectral broadening, and waveform configuration were measured at each site. RESULTS: An increase in peak systolic velocity of more than 200% accurately predicted a 50% or greater reduction in luminal diameter on angiography (70% sensitivity, 96% specificity). The presence of spectral broadening and an abnormal waveform shape were found to correlate poorly with the degree of stenosis. Analysis of variance showed no significant difference between observers in velocity measurements (p = 0.78). CONCLUSIONS: We conclude that although stenoses of greater than 50% can be distinguished from minor stenoses, more precise definition of the degree of narrowing is unlikely. The good repeatability of the velocity ratio makes it an excellent tool for monitoring major changes in the progression of disease.

Analysis of Variance↗
PubMed1993

Accuracy and reproducibility of duplex ultrasound imaging in a phantom model of femoral artery stenosis.

PURPOSE: The improvement of management strategies in patients with intermittent claudication might depend on a better understanding of the natural history of femoral atherosclerosis. The grading of stenoses, the monitoring of their progression, and the assessment of response to treatment are critically dependent on a method's accuracy and variability. Duplex ultrasound imaging provides a noninvasive way of measuring localized disease, but there has been relatively little objective evaluation of its accuracy and reproducibility. The aim of this study was to evaluate the accuracy and variability of duplex velocity ratio measurements of stenosis. METHODS: In a laboratory flow model of the femoral artery, 14 concentric and eccentric stenoses were examined five times by three sonographers. Measurements were then repeated with a standardized technique in which Doppler angle and aperture position were fixed, giving a total of 420 measurements. RESULTS: Velocity ratio showed good correlation with degree of stenosis, R2 = 0.996. Intraobserver variability was low, but interobserver variability was significant with more severe stenosis (p = 0.002, analysis of variance). Standardization of the technique did not improve accuracy or variability. The 95% confidence limit was +/- 20% for a single reading of velocity ratio for stenoses of > 50% diameter reduction. CONCLUSIONS: We conclude that duplex ultrasound imaging can be used to accurately grade arterial stenosis in this range, and the potential exists for noninvasive monitoring of the progression of preocclusive femoral atherosclerosis and its response to treatment. In addition, repeated measurements of velocity ratio over time should be made by the same observer.

Analysis of Variance↗
PubMed1992

Serum cholesterol, triglycerides, and aggression in the general population.

A higher than expected number of violent deaths and suicides in coronary prevention trials has provoked interest in the possibility that low serum cholesterol concentrations are associated in the general population with personality characteristics predisposing to aggressive and suicidal behaviour. We have investigated this possibility in the Edinburgh Artery Study. We measured serum lipid concentrations in blood samples taken from fasting subjects and assessed personality characteristics on the Bedford Foulds Personality Deviance Scales in a random sample of 1592 men and women aged 55-74 years, selected from age-sex registers of ten general practices in Edinburgh. Serum cholesterol concentration was not significantly associated with aggression in men, but it was associated in multivariate analysis (though not univariate analysis) with denigratory attitudes towards others among women. However, serum triglyceride concentration was related, especially in men, to hostile acts (r = 0.13, p < 0.001) and domineering attitude (r = 0.12, p < 0.001) independently of age, total and HDL cholesterol, cigarette smoking, and alcohol consumption. Subjects taking part in prevention trials have higher triglyceride concentrations than the general population and the relation between serum triglyceride concentration and aggression merits further investigation.

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PubMed1992

The Edinburgh Claudication Questionnaire: an improved version of the WHO/Rose Questionnaire for use in epidemiological surveys.

The WHO/Rose Questionnaire on intermittent claudication was developed in 1962 for use in epidemiological surveys, and has been widely used. Several population studies have shown, however, that it is only moderately sensitive (60-68%), although highly specific (90-100%). In this study, reasons for the poor sensitivity and good specificity were determined following its application to 586 claudicants and to 61 subjects with other causes of leg pain. The results showed two important findings: firstly, that over half of the false negatives were produced by one question alone; and secondly that only three questions were required to maintain the specificity of the questionnaire. This knowledge, in conjunction with the pre-testing of additional questions, enabled a new questionnaire to be constructed: the "Edinburgh Claudication Questionnaire". This questionnaire was tested on 300 subjects aged over 55 years attending their general practitioner, and found to be 91.3% (95% CI 88.1-94.5%) sensitive and 99.3% (95% CI 98.9-100%) specific in comparison to the diagnosis of intermittent claudication made by a physician. The repeatability of the questionnaire after 6 months was excellent (kappa = 0.76, p < 0.001). These results suggest that this revised version of the WHO/Rose Questionnaire should be adopted for use in future epidemiological surveys of peripheral vascular disease.

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PubMed1991

Doppler colour flow imaging in peripheral arterial disease.

Duplex scanning is unique in its ability to provide both anatomical and physiological information about the circulation, but it is time-consuming and difficult to perform. Technological advances now allow the Doppler information to be colour-coded, making scanning both quicker and more accurate. This article describes the technique and potential use of Doppler colour flow imaging in the investigation and treatment of peripheral arterial disease.

Arterial Occlusive Diseases↗