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Biomedical subjects

I A Baker

Publications and source records attributed to I A Baker.

At least 19 recordsLinked to original sources
PubMed1998

The relative power of heat-precipitation nephelometric and clottable (Clauss) fibrinogen in the prediction of ischaemic heart disease: the Caerphilly and Speedwell studies.

The Caerphilly and Speedwell studies have previously reported the predictive power of heat-precipitation, nephelometric, fibrinogen for 10-year incidence of ischaemic heart disease. A Clauss, clotting time, fibrinogen was also measured at baseline, but has not previously been reported. The predictive power of the two assays is compared. Both methods were employed on fasting blood samples from a total of 4391 men aged 45-63 years. Over the following 10 years 533 (12%) developed major ischaemic heart disease. Nephelometric fibrinogen was higher by 0.33 g/l among the men who developed disease; clottable fibrinogen was higher by 0.20 g/l. This difference is statistically significant (P=0.01). Relative odds of developing heart disease increased steadily to 3.53 (P<0.0001) in the 20% of men with the highest nephelometric fibrinogen; for clottable fibrinogen the corresponding relative odds increased to 2.24 (P<0.0001). When both measures of fibrinogen were included in logistic regression models together with age and smoking habit, the trend for incidence to increase with increasing nephelometric fibrinogen remained highly significant (P<0.0001), whereas for the Clauss fibrinogen the trend almost entirely disappeared (P = 0.37). We conclude that functional assays of clottable fibrinogen may not reflect all of the mechanisms which mediate the association between fibrinogen and cardiovascular disease and that assays of both 'heat precipitable' and 'clottable' fibrinogen should be included in all future prospective studies.

Aged↗
PubMed1997

Total and differential leukocyte counts as predictors of ischemic heart disease: the Caerphilly and Speedwell studies.

A number of studies have shown total leukocyte count to be a risk factor for ischemic heart disease, but there is little information on the role of the individual types of leukocyte, and the role of smoking is controversial. The Caerphilly and Speedwell studies recruited 4,860 men aged 45-63 years between 1979 and 1983 in South Wales and the West of England, respectively. At the 10-year follow-up, the total leukocyte count predicted ischemic heart disease events after adjusting for the classical risk factors, including smoking. Five-year follow-up results were available for differential white cell counts. The main contributor to the increase in total count in the men who developed disease was the neutrophil count. There was also a statistically significant increase in the eosinophil count.

Cohort Studies↗
PubMed1997

The Bristol Shared Care Glaucoma Study--validity of measurements and patient satisfaction.

BACKGROUND: The aims of the study were to determine (1) whether community optometrists are able to make valid measurements of visual parameters in patients with established or suspect primary open angle glaucoma and (2) patient satisfaction with follow-up by community optometrists. METHODS: A randomized study was carried out in the former county of Avon in South West England with patients allocated to follow-up by the hospital eye service or by community optometrists. The subjects were 403 patients with established or suspected primary open angle glaucoma attending Bristol Eye Hospital and meeting defined inclusion and exclusion criteria. The main outcome measures were 91) measurements of key visual parameters (intraocular pressure, visual fields and cup/disc ratio) made by hospital eye service and community optometrists, compared with a research clinic reference standard at baseline, and (2) patient satisfaction at baseline and at six months. RESULTS: Community optometrists were able to make measurements of comparable accuracy to those made in the hospital eye service. Patients were significantly more satisfied with a number of aspects of care provided by community optometrists, particularly those relating to waiting times, compared with those from the hospital eye service. CONCLUSIONS: Community optometrists are able to make measurements of key visual parameters in patients with established or suspect primary open angle glaucoma which are of comparable quality to the hospital eye service. Follow-up by community optometrists is acceptable to patients. The costs of each option are reported elsewhere.

Aged↗
PubMed1996

Fibrinogen, viscosity and the 10-year incidence of ischaemic heart disease.

AIMS: To use the ten year follow-up of the Caerphilly and Speedwell studies to assess the contributions of fibrinogen and viscosity to the prediction of risk of ischaemic heart disease. METHODS AND RESULTS: Caerphilly and Speedwell are prospective studies based on representative samples of middle-aged males. Ischaemic heart disease morbidity and mortality were defined using hospital notes, repeat electro-cardiographs and death certificates. There were 603 incident events among the 4860 men. Age-adjusted relative odds of ischaemic heart disease increased to 3.3 and 3.4 in the 20% of men with the highest levels of fibrinogen and viscosity, respectively. After standardizing for the major cardiovascular risk factors, these relative odds were 2.2 (95% confidence interval 1.6 to 3.1) for fibrinogen and 2.3 (95% confidence interval 1.7 to 3.2) for viscosity. When fibrinogen and viscosity were entered jointly, both remained significant (P < 0.01) predictors. Incidence of ischaemic heart disease increased with increasing fibrinogen at every level of viscosity, and vice versa. Interactions with lipids were also examined. There was no support for the suggestion that risk is independent of cholesterol level when fibrinogen is low. CONCLUSIONS: Fibrinogen and viscosity are powerful, long term and independent predictors of the risk of ischaemic heart disease.

Age Distribution↗
PubMed1995

The Bristol Shared Care Glaucoma Study: study design.

The purpose of this study was the evaluation of community based optometric monitoring of stable glaucoma patients and glaucoma suspects compared to the routine Hospital Eye Services (HES) monitoring. Four hundred and five subjects were recruited from routine outpatient clinics at the Bristol Eye Hospital. All eligible participants were seen in the routine hospital clinic and then within two months were given a 'Gold Standard Assessment' (GSA) by an independent research team. Participants then visited one of 12 glaucoma-trained optometrists, for a standard battery of tests. Randomisation resulted in 204 subjects being allocated to community care, with reviews on a six monthly basis, with 201 who remained a control group within the hospital. Referral criteria were established to enable optometric detection of apparent glaucomatous progression. A questionnaire was used to assess patient satisfaction with both care types. Additionally a cost analysis exercise was performed.

Community Health Services↗
PubMed1994

Does non-diabetic hyperglycemia predict future IHD? Evidence from the Caerphilly and Speedwell studies.

We have examined the risk of subsequent ischemic heart disease (IHD) in men according to their initial fasting plasma glucose level in a prospective cohort study (Caerphilly Collaborative Study) of 4860 middle aged men from South Wales and Bristol, U.K. Ninety-four men reported themselves to be diabetic at initial screening and fasting venous plasma glucose levels were determined in these men and in a further 4519 non-diabetic men. At follow-up new IHD events occurred twice as commonly in diabetics compared to non-diabetics and overall mortality was increased 4-fold. Among non-diabetics however, increased IHD events only occurred in men with fasting values at the upper end of the distribution of baseline plasma glucose values [at 6.8 mmol/l (122 mg/dl) or more]. This association was reduced, but remained statistically significant, after adjusting for factors associated with plasma glucose levels; body mass index, plasma triglyceride, smoking habit and pre-existing IHD. In conclusion there is no evidence of a consistent, graded increase in risk of IHD by initial fasting plasma glucose level although the risk is significantly increased in men with baseline plasma values at 6.8 mmol/l (122 mg/dl) or more, and also in diabetics. This study suggests that such levels probably represent a pre-diabetic state in many individuals. Appropriate non-pharmacological intervention may be useful in halting the progression to the diabetic state, although this should be tested in experimental studies.

Blood Glucose↗
PubMed1994

Associations of the HDL2 and HDL3 cholesterol subfractions with the development of ischemic heart disease in British men. The Caerphilly and Speedwell Collaborative Heart Disease Studies.

BACKGROUND: The relative importance of HDL2 and HDL3 cholesterol as risk factors for ischemic heart disease (IHD) is still uncertain. Their associations with the incidence of IHD in the Caerphilly and Speedwell prospective studies are described. METHODS AND RESULTS: The two studies have a common core protocol and are based on a total of 4860 middle-aged men from the general population. The first follow-up was at a nearly constant interval of 5.1 years in Caerphilly and 3.2 years in Speedwell: 251 major IHD events had occurred. Lipid levels were measured on fasting samples. Different laboratories were used by the two studies. Each laboratory used ultracentrifugation to separate HDL2 and HDL3. Both subfractions were inversely associated with risk of IHD. Standardized relative odds of developing major IHD were 0.95 (95% confidence interval [CI], 0.80 to 1.14) for HDL2 cholesterol and 0.83 (95% CI, 0.68 to 1.00) for HDL3 cholesterol in Caerphilly and 0.76 (95% CI, 0.57 to 1.01) for HDL2 and 0.64 (95% CI, 0.49 to 0.83) for HDL3 in Speedwell. The association with incident IHD appeared to be stronger for HDL3 in both areas. No linear combination of the two subfractions was a better predictor of IHD than total HDL cholesterol alone. CONCLUSIONS: In British men, both HDL2 and HDL3 cholesterol are inversely associated with the incidence of IHD. However, the prediction of the risk of IHD from total HDL cholesterol alone could not be improved upon by measurement of the two HDL subfractions. The relative value of the two HDL subfractions as predictors of risk is still unresolved. The uncertainty may be due, at least in part, to problems associated with their measurement.

Cholesterol, HDL↗
PubMed1992

Height: a risk marker for ischaemic heart disease: prospective results from the Caerphilly and Speedwell Heart Disease Studies.

The predictive power of height for future ischaemic heart disease (IHD) was examined in 4860 men from two communities in South Wales and the West of England. At follow-up, men in the shortest fifth of the height distribution had experienced twice as many incident IHD events (fatal and non-fatal myocardial infarction) as was the case for men from the tallest fifth. Adjustment for age, social class and smoking habit failed to alter these relationships significantly. In the data from South Wales, determinants of height were examined; birth rank and number of siblings showed a trend with height. This trend was found only in men whose fathers were manual workers and may be related to inadequate nutrition in the higher birth ranks and larger families. These results support the suggestion that early childhood factors may be relevant to IHD in middle age and possible mechanisms are discussed.

Birth Order↗
PubMed1992

Plasma triglyceride and high density lipoprotein cholesterol as predictors of ischaemic heart disease in British men. The Caerphilly and Speedwell Collaborative Heart Disease Studies.

OBJECTIVE: To assess the roles of plasma triglyceride and high density lipoprotein (HDL) cholesterol concentrations in predicting ischaemic heart disease. DESIGN: Two prospective cohort studies with common core protocols. SETTING AND PARTICIPANTS: Both cohorts are 100% samples of middle aged men. In Caerphilly the 2512 men were living within a defined area. In Speedwell the 2348 men were registered with local general practitioners. MAIN OUTCOME MEASURES: Fasting blood samples were taken at initial examination and plasma lipid concentrations were measured. Major ischaemic heart disease events were assessed from hospital notes, death certificates, and electrocardiograms. RESULTS: At first follow up, after an average of 5.1 years in Caerphilly and 3.2 years in Speedwell, 251 major ischaemic heart disease events had occurred. Men with triglyceride concentrations in the top 20% of the distribution had a relative odds value for ischaemic heart disease of 2.3 (95% confidence interval (95% CI) 1.3 to 4.1) compared with men in the bottom 20%, after adjusting for both plasma total and HDL cholesterol, and non-lipid risk factors. Men in the lowest 20% of the distribution of HDL cholesterol concentration had a relative odds value of 1.7 (95% CI 1.0 to 2.8) compared with the top 20%, after adjustment was made for total cholesterol and triglyceride concentrations, and non-lipid risk factors. These relations were not caused by beta blockers, which were being taken by 5% of the men. CONCLUSIONS: Plasma triglyceride concentration predicts major ischaemic events after allowance is made for total and HDL cholesterol concentrations and other risk factors. In these populations, triglyceride is a more important predictor than total cholesterol concentration.

Adrenergic beta-Antagonists↗
PubMed1991

General practitioners' opinions of health services available to their patients.

OBJECTIVES: To establish a means for general practitioners to express their views about health services available to their patients, to identify services that general practitioners perceive as most in need of improvement, and to establish good working relations between the health authority's purchasing team and local general practitioners. DESIGN: Postal questionnaire survey of general practitioners. SETTING: Bristol and Weston health district. SUBJECTS: 226 general practitioners, of whom 171 replied. MAIN OUTCOME MEASURES: Scores of quality and quantity of hospital and community services, frequency that services were identified as priorities for improvement, and the nature of written comments received about services. RESULTS: There was considerable agreement among respondents about which services were adequate and which were inadequate. Most services were perceived as at least adequate in both quality and quantity, but seven services were perceived by more than 60% (102) of doctors as inadequate or worse in quantity and eight by 10% (17) of doctors as poor in quality. Orthopaedics, ophthalmology, care of elderly people, and physiotherapy were the services doctors most wanted improved. CONCLUSIONS: A postal questionnaire is an acceptable and accurate method of obtaining general practitioners' views about services available to their patients. General practitioners' priorities differ from those obtained from hospital medical advisory mechanisms.

Attitude of Health Personnel↗
PubMed1991

Fibrinogen, viscosity, and white blood cell count are major risk factors for ischemic heart disease. The Caerphilly and Speedwell collaborative heart disease studies.

BACKGROUND: Recent studies have suggested that hemostatic factors and white blood cell count are predictive of ischemic heart disease (IHD). The relations of fibrinogen, viscosity, and white blood cell count to the incidence of IHD in the Caerphilly and Speedwell prospective studies are described. METHODS AND RESULTS: The two studies have a common core protocol and are based on a combined cohort of 4,860 middle-aged men from the general population. The first follow-up was at a nearly constant interval of 5.1 years in Caerphilly and 3.2 years in Speedwell; 251 major IHD events had occurred. Age-adjusted relative odds of IHD for men in the top 20% of the distribution compared with the bottom 20% were 4.1 (95% confidence interval, 2.6-6.5) for fibrinogen, 4.5 (95% confidence interval, 2.8-7.4) for viscosity, and 3.2 (95% confidence interval, 2.0-4.9) for white blood cell count. Associations with IHD were similar in men who had never smoked, exsmokers, and current smokers, and the results suggest that at least part of the effect of smoking on IHD is mediated through fibrinogen, viscosity, and white blood cell count. Multivariate analysis shows that white blood cell count is an independent risk factor for IHD as is either fibrinogen or viscosity, or possibly both. Jointly, these three variables significantly improve the fit of a logistic regression model containing all the main conventional risk factors. Further, a model including age, smoking habits, fibrinogen, viscosity, and white blood cell count predicts IHD as well as one in which the three hemostatic/rheological variables are replaced by total cholesterol, diastolic pressure, and body mass index. CONCLUSION: Jointly, fibrinogen, viscosity, and white blood cell count are important risk factors for IHD.

Blood Viscosity↗
PubMed1990

The diets of men in four areas of the UK: the Caerphilly, Northern Ireland, Edinburgh and Speedwell studies.

Nutrient intakes in four areas of the UK were compared, 7-d weighed intake data were obtained for representative community samples of middle-aged men in Caerphilly (South Wales), Northern Ireland, Edinburgh and Bristol (Speedwell). Intakes of energy were higher in Edinburgh than in the other three areas, but following allowance for this, differences in nutrient intakes were very small. The exceptions were P/S ratio and alcohol consumption. The P/S ratio for Northern Ireland (0.38) was considerably higher than that for the other areas (0.30 to 0.32). The proportion of heavy drinkers was higher in Edinburgh (15 per cent) than in other areas (5-9 per cent) and the proportion of abstainers was highest in Northern Ireland (38 per cent). Differences in nutrient intakes did not parallel the differences in ischaemic heart disease (IHD) mortality rates between the areas.

Alcohol Drinking↗
PubMed1988

Haemostatic and other risk factors for ischaemic heart disease and social class: evidence from the Caerphilly and Speedwell studies.

There are marked associations between social class and mortality from ischaemic heart disease (IHD). Using data from the Caerphilly and Speedwell Collaborative Heart Disease Studies the relationships between a number of known risk factors for IHD and social class are explored. The overall conclusions are that lipids and obesity are unlikely to play any part in explaining social differences in ischaemic heart disease. Blood pressure, particularly stystolic pressure, could be involved but the two data sets are inconsistent and associations are only shown in Speedwell. There are marked differences in the haemostatic related variables in the various social classes and the pattern of these is similar in Caerphilly and Speedwell. It is possible therefore that the class pattern of IHD is generated, in part at least, by differences in haemostatic mechanisms. These differences in haemostatic function are almost entirely due to the large social class differences in smoking habit. It is possible therefore that the class differences in IHD result from differences in smoking habit.

Blood Pressure↗
PubMed1988

Prevalence of ischaemic heart disease: the Caerphilly and Speedwell surveys.

Mortality from ischaemic heart disease remains high in the United Kingdom, and the present report describes the prevalence of the various epidemiological manifestations of the disease in two recent community studies with a common core protocol, each containing samples of over 2000 men, carried out in South Wales (Caerphilly) and the West of England (Speedwell, Bristol). The prevalence of electrocardiographic evidence of ischaemia was similar in the two communities--8.7% of men aged 45-49 years rising to 18.6% in men aged 55-59 years in the samples from South Wales, and 8.0% and 17.2% respectively in the Bristol population. The overall prevalence of angina was 7.7% in Caerphilly and 7.8% in Speedwell in men aged 45-59 years, but symptoms of severe chest pain were more commonly reported in South Wales than in Speedwell (10.1% compared with 6.3%). The data, however, suggested that the overall prevalence of ischaemic heart disease was very similar in the two areas. The prevalence of ischaemic heart disease was compared with that found in other population studies carried out in the United Kingdom and was higher than that found when employed men only were studied. There were substantial differences in mortality between the two areas; possible reasons for this are differences in community or medical services, smoking habit, or unemployment rates.

Age Factors↗
PubMed1988

Diagnosis of past history of myocardial infarction in epidemiological studies: an alternative based on the Caerphilly and Speedwell surveys.

In epidemiological studies the diagnosis of a past history of myocardial infarction is made from the answer to a single question: "Have you ever had a severe pain across the front of your chest lasting for half an hour or more?" Two additional questions, which form an optional part of the London School of Hygiene and Tropical Medicine chest pain questionnaire, were used in two large community studies, with other information to determine the likely accuracy of the diagnosis ("Did you see a doctor about this pain?" If so, "What did he say it was?") The prevalence of possible myocardial infarction from the use of the single question was significantly higher among men from South Wales than among men from Speedwell, Bristol (10.1% and 6.9% respectively); in contrast, positive responses to the additional questions reduced the prevalence in the two populations to 5.8% and 4.9% respectively. These latter figures are very similar to those of self-reported coronary thrombosis in the two populations. Among subjects with positive responses to the additional questions the prevalence of ECG ischaemia was about 50%; in contrast, the prevalence of ECG ischaemia among those positive only to the severe chest pain question was very similar to that among those with no history of chest pain (12%). Preliminary mortality data show a similar classification of level of risk. These findings indicate that the false positive error rate for possible myocardial infarction could be significantly reduced by the use of two additional questions which form an optional part of the London School of Hygiene chest pain questionnaire but are rarely used. However, the present findings relate to populations with uniform levels of adequately accessible medical care; comparisons between populations with different levels of medical care will require cautious interpretation.

Chest Pain↗
PubMed1988

Associations of alcohol consumption with plasma high density lipoprotein cholesterol and its major subfractions: the Caerphilly and Speedwell Collaborative Heart Disease Studies.

In surveys of 4860 middle-aged men in Caerphilly (South Wales) and Speedwell (Bristol) alcohol consumption has been related to high density lipoprotein (HDL) cholesterol and its major subfractions, HDL2 and HDL3, measured in a single fasting blood sample. The results confirm that high density lipoprotein cholesterol concentration increases as the amount of alcohol regularly consumed increases. The relationship appears to be linear and is independent of age, smoking habit, body mass index, low density lipoprotein cholesterol and plasma total triglyceride. This rise in HDL cholesterol is not mediated through either HDL2 cholesterol or HDL3 cholesterol alone. Both subclasses increase significantly and by similar amounts with increasing alcohol intake.

Alcohol Drinking↗
PubMed1987

Some long term effects of smoking on the haemostatic system: a report from the Caerphilly and Speedwell Collaborative Surveys.

Data from two community studies on men from South Wales and the west of England suggest that the effects of smoking on the haemostatic system remain for many years after giving up. Long term correlations between several variables, including plasma fibrinogen and white cell count, and the length of time after giving up were seen in ex-smokers. Dose response relations were apparent in current smokers in terms of the white cell count and two haematological variables, the packed and mean cell volumes. These long term correlations probably reflect the toxicity of other agents in tobacco smoke besides nicotine and carbon monoxide, which act only in the short term. Identification of these agents may further our understanding of the mechanism by which cigarette smoking is associated with atherosclerotic disease.

Blood Viscosity↗