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Biomedical subjects

T W Meade

Publications and source records attributed to T W Meade.

At least 55 records · Page 3Linked to original sources
PubMed1997

Is there any evidence for a protective effect of antithrombotic medication on cognitive function in men at risk of cardiovascular disease? Some preliminary findings.

To explore whether antithrombotic medication may protect against cognitive decline, tests of verbal memory, attention, abstract reasoning, verbal fluency, and mental flexibility were administered to 405 men at risk of cardiovascular disease. These subjects were a subgroup of those who had been participating in a randomised double blind factorial trial of low dose aspirin (75 mg daily) and low intensity oral anticoagulation with warfarin (international normalised ratio of 1.5) at 35 general practices across the United Kingdom for at least five years, were at least 55 years old at trial entry, and had been randomly allocated to one of four groups: active warfarin and active aspirin, active warfarin and placebo aspirin, placebo warfarin and active aspirin, and double placebo. Verbal fluency and mental flexibility were significantly better in subjects taking antithrombotic medication than in subjects taking placebo. Aspirin may have contributed more than warfarin to any beneficial effect. These results provide tentative evidence that antithrombotic medication may protect cognitive function in men at risk of cardiovascular disease.

Aged↗
PubMed1997

Platelet counts and aggregation measures in the incidence of ischaemic heart disease (IHD).

Although studies in those who have already experienced clinical episodes of ischaemic heart disease (IHD) have suggested properties of platelets influencing recurrence, there is limited information on the value of platelet tests in predicting first episodes of IHD. One study has suggested that a raised platelet count and increased aggregability in response to adenosine diphosphate (ADP) may increase IHD incidence but the numbers of IHD events involved were small. The larger Northwick Park Heart Study (NPHS) included platelet count and both ADP and adrenaline-induced aggregation and this paper presents their associations with subsequent IHD. Platelet counts were performed in 1369 white NPHS men aged between 40 and 64 at recruitment, of whom 181 subsequently experienced a major episode of IHD over a follow-up period of 16.1 years. Platelet count was unrelated to the incidence of IHD. ADP-induced aggregation was performed in a random sample of 740 men in whom 66 IHD events occurred during the subsequent 10.1 years, aggregability being measured both as ED50, the ADP dose at which aggregation occurred at half its maximum velocity, and also as EMR, the maximum rate of aggregation achieved. Neither measurement showed any association with IHD incidence, nor did similar measurements in 460 men in whom adrenaline-induced aggregation was also carried out. There are at least three possible explanations for the lack of any association between the measures of aggregability used and IHD. First, the large within-person variability of platelet aggregation tests may make the demonstration of any associations difficult, though the study had reasonable power to show effects with ADP. Secondly, the tests used may not be a valid index of the contribution of platelet function to thrombosis and IHD. However, the clear effect of several personal and demographic influences associated with IHD on the tests used brings this explanation into question. Thirdly, the role of platelets in thrombogenesis may be determined mainly by plasma influences such as fibrinogen, rather than by intrinsic properties of platelets themselves. Platelet counts within the physiological range and the aggregation tests used in this and in some other studies are of no value as indices of the risk of first episodes of IHD.

Adult↗
PubMed1995

Randomised comparison of chiropractic and hospital outpatient management for low back pain: results from extended follow up.

OBJECTIVE: To compare the effectiveness over three years of chiropractic and hospital outpatient management for low back pain. DESIGN: Randomised allocation of patients to chiropractic or hospital outpatient management. SETTING: Chiropractic clinics and hospital outpatient departments within reasonable travelling distance of each other in 11 centres. SUBJECTS: 741 men and women aged 18-64 years with low back pain in whom manipulation was not contraindicated. OUTCOME MEASURES: Change in total Oswestry questionnaire score and in score for pain and patient satisfaction with allocated treatment. RESULTS: According to total Oswestry scores improvement in all patients at three years was about 29% more in those treated by chiropractors than in those treated by the hospitals. The beneficial effect of chiropractic on pain was particularly clear. Those treated by chiropractors had more further treatments for back pain after the completion of trial treatment. Among both those initially referred from chiropractors and from hospitals more rated chiropractic helpful at three years than hospital management. CONCLUSIONS: At three years the results confirm the findings of an earlier report that when chiropractic or hospital therapists treat patients with low back pain as they would in day to day practice those treated by chiropractic derive more benefit and long term satisfaction than those treated by hospitals.

Adult↗
PubMed1995

Combined use of aspirin and warfarin in primary prevention of ischemic heart disease in men at high risk.

The combination of aspirin and warfarin is likely to be more effective than either agent alone in the prevention of ischemic heart disease (IHD), but its practical value also crucially depends on a low incidence of serious bleeding. The occurrence of bleeding of different degrees of severity is being established in the Thrombosis Prevention Trial of primary prevention in men aged 45-69 years at increased risk of IHD, in which 75 mg aspirin and warfarin dosed to an international normalized ratio of 1.5 are used in a factorial design. The annual risk of serious bleeding, i.e., requiring transfusion or surgery, may be about 1 in 500 for those on active treatment, whether this consists of both aspirin and warfarin or either alone. Less serious degrees of bleeding are significantly increased by the combination of aspirin and warfarin compared with either alone and by either alone compared with placebo. The risk of serious bleeding is probably acceptable if low dosages are used.

Aged↗
PubMed1995

Fetal and infant growth and cardiovascular risk factors in women.

OBJECTIVE: To examine whether cardiovascular risk factors in women are related to fetal and infant growth. DESIGN: Follow up study of women born 1923-30 whose birth weights and weights at one year were recorded. SETTING: Hertfordshire. SUBJECTS: 297 women born and still living in East Hertfordshire. MAIN OUTCOME MEASURES: Plasma glucose and insulin concentrations during a standard oral glucose tolerance test; fasting plasma proinsulin and 32-33 split proinsulin concentrations; blood pressure; fasting serum total, low density lipoprotein and high density lipoprotein cholesterol, triglyceride, and apolipoprotein A I and B concentrations; and plasma fibrinogen and factor VII concentrations. RESULTS: Fasting plasma concentrations of glucose, insulin, and 32-33 split proinsulin fell with increasing birth weight (P = 0.04, P = 0.002, and P = 0.0002 respectively, when current body mass index was allowed for). Glucose and insulin concentrations 120 minutes after an oral glucose load showed similar trends (P = 0.03 and P = 0.02). Systolic blood pressure, waist:hip ratio, and serum triglyceride concentrations also fell with increasing birth weight (P = 0.08, P = 0.07, and P = 0.07 respectively), while serum high density lipoprotein cholesterol concentrations rose (P = 0.04). At each birth weight women who currently had a higher body mass index had higher levels of risk factors. CONCLUSION: In women, as in men, reduced fetal growth leads to insulin resistance and the associated disorders: raised blood pressure and high serum triglyceride and low serum high density lipoprotein cholesterol concentrations. The highest values of these coronary risk factors occur in people who were small at birth and became obese. In contrast with men, low rates of infant growth did not predict levels of risk factors in women.

Apolipoproteins↗
PubMed1995

Hormone replacement therapy and cardiovascular disease: the case for a randomized controlled trial.

The menopause is associated with an increased risk of developing cardiovascular disease. Oestrogen may influence various metabolic pathways which contribute to the pathogenesis of cardiovascular disease, and observational studies suggest that in postmenopausal women oral oestrogen replacement therapy confers some protection against coronary heart disease and to a lesser extent against stroke. What is not clear is the magnitude of the cardioprotective effect and the overall balance of long-term benefits and hazards. Research is also required to establish the relative effects of oestrogen replacement therapy and combined or opposed hormone replacement therapy (HRT) where progestogen is added to counter the proliferative action of oestrogen on the endometrium. A large randomized controlled trial is the only way to provide accurate estimates of the cardioprotective effect of HRT and of other long-term benefits and hazards. Feasibility studies undertaken through the UK Medical Research Council (MRC) General Practice Research Framework show that such a trial is acceptable to patients and their doctors. Recruitment and withdrawal rates indicate that a trial of sufficient size to show a 25% reduction in cardiovascular disease with 90% power at the 1% level would be feasible. The full trial is costly and it is proposed that the UK collaborates with other countries in a major international trial to complement the Women's Health Initiative trial in the USA. Feasibility studies in Europe are underway, the design and scientific rationale for the trial have been approved by the UK MRC and it is hoped that recruitment to the full-scale trial can begin soon.

Cardiovascular Diseases↗
PubMed1995

Fibrinogen in ischaemic heart disease.

Fibrinogen contributes to both pathological and clinical manifestations of ischaemic heart disease (IHD). Several cross-sectional angiographic studies have shown correlations between the fibrinogen level and the extent of coronary artery disease. The largest of these studies suggests that this relationship is due mainly to luminal occlusion, strengthening the evidence that high fibrinogen levels are thrombogenic. The growing number of prospective studies that have included fibrinogen measurements consistently show a direct, independent and statistically significant association between fibrinogen level and the subsequent incidence of IHD, this association being about as strong as the relation between cholesterol and IHD, for example. The fibrinogen level is also associated with the recurrence of IHD in those who have survived a myocardial infarction and with the onset and recurrence or progression of cerebrovascular disease and lower extremity arterial disease. Besides a contribution to coronary artery changes, high fibrinogen levels predispose to IHD through influences on blood and plasma viscosity, platelet aggregability and the amount of fibrin produced when coagulation is initiated. Progress towards the standardization of methods for measuring fibrinogen increasingly justifies its inclusion in the IHD risk profile. Establishing the value of agents that lower fibrinogen levels is now a high research priority, mainly for clinical reasons but also as part of the evidence for clarifying the nature of the association of raised levels with arterial disease.

Blood Viscosity↗
PubMed1995

Plasma concentrations of fibrinogen and factor VII in adult life and their relation to intra-uterine growth.

To examine the relation between fetal development and plasma concentrations of fibrinogen and factor VII in adult life we followed up 202 men and women, now aged around 50 years, who had been measured in detail at birth. Plasma concentrations of fibrinogen were related to weight and abdominal circumference at birth. In men, after adjustment for cigarette smoking and current obesity, plasma concentrations of fibrinogen fell by 0.12 g/l (95% CI 0.05-0.19) for each pound increase in birthweight and by 0.10 g/l (95% CI 0.03-0.17) for each inch increase in abdominal circumference. In contrast, analysis of the data for women showed no statistically significant relation between plasma fibrinogen concentration and weight or abdominal circumference at birth. No relation was seen between concentrations of factor VII and measurements made at birth in either sex. These findings suggest that, in men, reduced growth of the liver in fetal life has a long-term influence on fibrinogen metabolism.

Abdomen↗
PubMed1995

Exercise and haemostatic function.

To reduce the risk of ischaemic heart disease, vigorous exercise has to be maintained over time. This suggests that the benefit is at least partly due to a short-term effect, such as an influence on the haemostatic system and thrombogenic potential. A high plasma fibrinogen level is strongly and independently associated with the incidence of ischaemic heart disease, and the effects of exercise on fibrinogen have now been extensively investigated. One randomized controlled trial and several large epidemiological studies show that vigorous exercise lowers the plasma fibrinogen level by an amount that would reduce the risk of ischaemic heart disease by 7 or 8% on a conservative estimate, along with additional benefits due to any favourable effects on blood pressure and lipids, for example. However, unaccustomed exertion raises the immediate risk of ischaemic heart disease probably, at least in part, through a short-term increase in coagulability. Thus, those who are not accustomed to physical exertion should approach it gradually in the early stages of exercise programmes.

Coronary Disease↗
PubMed1995

Do risk factors change in men at high risk of coronary heart disease? Observations on the effect of health promotion in primary care.

BACKGROUND: There has been an increasing focus on the identification and modification of risk factors for coronary heart disease (CHD) in primary care. One approach is to concentrate activity on those at high risk of CHD. METHODS: This study was a prospective follow-up after CHD risk assessment and intervention designed to determine whether middle-aged men identified as being at high risk of CHD in primary care, who participated in a randomized controlled trial of antithrombotic medication, reduced their risk factor profile in response to the health promotion given in all practices, whatever their treatment allocation. We studied 4316 men aged 45-69 years (who had not suffered a previous myocardial infarction or stroke) identified at screening in 81 general practices in the UK as being at high risk of coronary heart disease. The changes in the prevalence of smoking and in blood pressure, serum cholesterol level, body mass index and plasma fibrinogen level were recorded for a period of up to 2 years after entry into the trial. The use of standard health education materials and of more intensive individual interventions was substantial. There were regular opportunities through nurses and consultations with general practitioners for continuing advice about risk factors. RESULTS: The prevalence of current smoking fell during the trial but it was still 37% at 2 years. There was a significant decrease in blood pressure due first to regression to the mean but then to the trial's treatment protocol and accommodation to measurement. There were small falls between screening and entry in body mass and levels of serum cholesterol and fibrinogen, again due largely to regression to the mean; subsequent changes in these characteristics were negligible. CONCLUSION: Sustained and quite intensive health promotion activity had only a limited effect in men identified as being at high risk of CHD. In particular, there was little change in body mass or serum cholesterol. Although improved blood pressure control and a moderate reduction in the prevalence of smoking can be achieved, further research is needed to determine the most effective methods of risk factor reduction in order to realize the full potential of the 'high-risk' approach to the prevention of CHD.

Aged↗
PubMed1994

Seasonal variations of plasma fibrinogen and factor VII activity in the elderly: winter infections and death from cardiovascular disease.

There are approximately 20,000 excess deaths from cardiovascular disease each winter in England and Wales. The reasons for the excess have not been fully elucidated. For one year, we studied 96 men and women aged 65-74 living in their own homes in order to examine seasonal variation in plasma fibrinogen and factor VII clotting activity (FVIIc), and to investigate relationships with infection and other cardiovascular-disease risk factors. Both fibrinogen and FVIIc plasma values were greater in winter with estimated winter-summer differences (confidence intervals) of 0.13 (0.05-0.20) g/L for fibrinogen and 4.2 (1.2-7.1)% of standard for FVIIc. These differences could account for 15% and 9% increases in ischaemic heart disease risk in winter respectively. After adjustment for confounding by season, fibrinogen was strongly related to neutrophil count (p < 0.0001), C-reactive protein (p < 0.0001), alpha 1-antichymotrypsin (p < 0.0001), and self-reported cough (p < 0.0001) and coryza (p = 0.0004), but not to ambient temperature. Therefore, we suggest that seasonal variation in fibrinogen might be induced by winter respiratory infections via activation of the acute phase response. Seasonal variations in the cardiovascular risk factors fibrinogen and FVIIc provide further possible explanations for the marked seasonal variation in death from ischaemic heart disease and stroke in the elderly.

Acute-Phase Proteins↗