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Biomedical subjects

T A Welborn

Publications and source records attributed to T A Welborn.

At least 19 recordsLinked to original sources
PubMed2006

Diagnostic thresholds for diabetes: the association of retinopathy and albuminuria with glycaemia.

AIM: We examined the association of fasting plasma glucose (FPG), 2-h plasma glucose (2hPG) and HbA1c with retinopathy and microalbuminuria using both deciles of glycaemia and change point models, to validate current diagnostic criteria for diabetes and to identify therapeutic thresholds for glycaemic control. METHODS: The Australian Diabetes Obesity and Lifestyle study (AusDiab), conducted in 1999-2000, included adults aged > or =25 years from 42 randomly selected areas of Australia. Retinopathy and albuminuria were assessed in participants identified as having diabetes (based on self report and oral glucose tolerance test), impaired fasting glucose, impaired glucose tolerance and in a random sample with normal glucose tolerance. Data were available for 2,182 participants with retinal photographs and 2,389 with urinary albumin/creatinine results. RESULTS: The prevalence of retinopathy in the first 8 deciles of FPG and HbA1c and the first 9 deciles of 2hPG were 7.2, 6.6, and 6.3%, respectively and showed no variation with increasing glucose or HbA1c. Above these levels, the prevalence rose markedly to 18.6% in the top 2 deciles of FPG, 21.3% in the top 2 deciles of HbA1c and 10.9% in the top decile of 2hPG. The thresholds for increasing prevalence of retinopathy were 7.1 mmol/l for FPG, 6.1% for HbA1c and 13.1 mmol/l for 2hPG. The prevalence of microalbuminuria rose gradually across deciles of each glycaemic measure. Thresholds were less clear than for retinopathy, but were seen at a FPG of 7.2 mmol/l and HbA1c of 6.1%, with no evidence of a threshold effect for 2hPG. CONCLUSIONS: The prevalence of retinopathy rose dramatically in the highest deciles of each glycaemic measure, while for microalbuminuria the increase of prevalence was more gradual. The FPG values corresponded well with the WHO diagnostic cut-point for diabetes, however the 2hPG value did not. HbA1c thresholds were similar for both retinopathy and microalbuminuria and compared well to values shown in other studies. These results support current targets for FPG and HbA1c in preventing microvascular complications.

Aged↗
PubMed2005

Associations of TV viewing and physical activity with the metabolic syndrome in Australian adults.

AIMS/HYPOTHESIS: We analysed a sample of Australian adults to determine the strength of associations of TV viewing and participation in physical activity with the metabolic syndrome. METHODS: This population-based cross-sectional study included 6,241 adults aged > or =35 years who were free from diagnosed diabetes mellitus and self-reported ischaemic disease and were not taking lipid-lowering or antihypertensive drugs. The metabolic syndrome was defined according to the 1999 World Health Organization criteria. Participants self-reported TV viewing time and physical activity time for the previous week. RESULTS: The adjusted odds ratio of having the metabolic syndrome was 2.07 (95% CI 1.49-2.88) in women and 1.48 (95% CI 0.95-2.31) in men who watched TV for >14 h per week compared with those who watched < or =7.0 h per week. Compared with those who were less active (<2.5 h per week), the odds ratio for the metabolic syndrome was 0.72 (95% CI 0.58-0.90) in men and 0.53 (95% CI 0.38-0.74) in women who were active (> or =2.5 h per week). Longer TV viewing (>14 h per week) was associated with an increased risk of insulin resistance, obesity and dyslipidaemia in both men and women. A total physical activity time of > or =2.5 h per week was associated with a reduced prevalence of both insulin resistance and dyslipidaemia in both sexes and reduced prevalence of both obesity and hypertension in women. CONCLUSIONS/INTERPRETATION: Increased TV viewing time was associated with an increased prevalence of the metabolic syndrome, while physical activity was associated with a reduced prevalence. Population strategies addressing the metabolic syndrome should focus on reducing sedentary behaviours such as TV viewing, as well as increasing physical activity.

Australia↗
PubMed2005

Effect of orlistat on cardiovascular disease risk in obese adults.

AIM: The aim of this study is to compare the effect of orlistat vs. placebo on the predicted 10-year cardiovascular disease (CVD) risk in obese people with one or more cardiovascular risk factors treated for 12 months, in conjunction with a fat-reduced, but otherwise ad libitum, diet. METHODS: A double-blind, randomized, placebo-controlled, parallel study was performed in conjunction with a fat-reduced diet and physical activity advice for 1 year. Participants (n = 339) from eight centres in Australia and New Zealand were randomized to either orlistat (120 mg) three times daily (n = 104 women, 66 men; mean +/- s.d. age = 52.0 +/- 7.5 years, body mass index (BMI) = 37.6 +/- 5.1 kg/m(2)) or placebo three times daily (n = 89 women, 80 men; age = 52.5 +/- 7.4 years, BMI = 38.0 +/- 4.9 kg/m(2)). The primary efficacy criterion was the 10-year risk of developing CVD calculated from the Framingham equation. Secondary efficacy criteria were body weight, waist circumference, blood pressure and serum concentrations of triglycerides, cholesterol (total, LDL and HDL), glucose, insulin and glycated haemoglobin and quality of life. RESULTS: There was no difference in the change in 10-year CVD risk between orlistat and placebo groups over 1 year. The orlistat group, however, had significant favourable changes in many of the individual CVD risk factors (total cholesterol, LDL-cholesterol, glucose, glycated haemoglobin, insulin, body weight and waist circumference) and one of the domains of quality of life measured by means of the SF-36 questionnaire (vitality), compared to the placebo group. Significant reductions in medication use for hypertension and diabetes were observed in the orlistat group, compared to those in placebo, but there were no significant differences in medication use for blood lipids. CONCLUSIONS: Orlistat may have reduced CVD risk, as judged by the favourable changes in individual risk factors and reductions in medication use, but the method used in order to measure absolute CVD risk in this study (Framingham CVD equation) was not sensitive enough to detect the changes in this relatively low-risk group (approximately 10% of risk of a CVD event over 10 years).

Adult↗
PubMed2003

Foot complications in Type 2 diabetes: an Australian population-based study.

AIMS: To determine the prevalence and risk factors for neuropathy and peripheral vascular disease (PVD) in the Australian diabetic population and identify those at high risk of foot ulceration. METHODS: The Australian Diabetes Obesity and Lifestyle study included 11 247 adults aged >or= 25 years in 42 randomly selected areas of Australia. Neuropathy and PVD were assessed in participants identified as having diabetes (based on self report and oral glucose tolerance test), impaired fasting glucose, impaired glucose tolerance and in a random sample with normal glucose tolerance (total n = 2436). RESULTS: The prevalence of peripheral neuropathy was 13.1% in those with known diabetes (KDM) and 7.1% in those with newly diagnosed (NDM). The prevalence of PVD was 13.9% in KDM and 6.9% in NDM. Of those with diabetes, 19.6% were at risk of foot ulceration. Independent risk factors for peripheral neuropathy were diabetes duration (odds ratio (95% CI) 1.73 (1.33-2.28) per 10 years), height (1.42 (1.08-1.88) per 10 cm), age (2.57 (1.94-3.40) per 10 years) and uric acid (1.59 (1.21-2.09) per 0.1 mmol/l). Risk factors for PVD were diabetes duration (1.64 (1.25-2.16) per 10 years), age (2.45 (1.86-3.22) per 10 years), smoking (2.07 (1.00-4.28)), uric acid (1.03 (1.00-1.06) per 0.1 mmol/l) and urinary albumin/creatinine ratio (1.11 (1.01-1.21) per 1 mg/mmol). CONCLUSIONS: The prevalence of neuropathy and PVD was lower in this population than has been reported in other populations. This may reflect differences in sampling methods between community and hospital-based populations. Nevertheless, a substantial proportion of the diabetic population had risk factors for foot ulceration.

Adult↗
PubMed2003

Waist circumference, waist-hip ratio and body mass index and their correlation with cardiovascular disease risk factors in Australian adults.

OBJECTIVES: To compare body mass index (BMI), waist circumference and waist-hip ratio (WHR) as indices of obesity and assess the respective associations with type 2 diabetes, hypertension and dyslipidaemia. DESIGN AND SETTING: A national sample of 11 247 Australians aged > or =25 years was examined in 2000 in a cross-sectional survey. MAIN OUTCOME MEASURES: The examination included a fasting blood sample, standard 2-h 75-g oral glucose tolerance test, blood pressure measurements and questionnaires to assess treatment for dyslipidaemia and hypertension. BMI, waist circumference and WHR were measured to assess overweight and obesity. RESULTS: The prevalence of obesity amongst Australian adults defined by BMI, waist circumference and WHR was 20.8, 30.5 and 15.8% respectively. The unadjusted odds ratio for the fourth vs. first quartile of each obesity measurement showed that WHR had the strongest relationship with type 2 diabetes, dyslipidaemia (women only) and hypertension. Following adjustment for age, however, there was little difference between the three measures of obesity, with the possible exceptions of hypertension in women, where BMI had a stronger association, and dyslipidaemia in women and type 2 diabetes in men, where WHR was marginally superior. CONCLUSIONS: Waist circumference, BMI and WHR identified different proportions of the population, as measured by both prevalence of obesity and cardiovascular disease (CVD) risk factors. Whilst WHR had the strongest correlations with CVD risk factors before adjustment for age, the three obesity measures performed similarly after adjustment for age. Given the difficulty of using age-adjusted associations in the clinical setting, these results suggest that given appropriate cut-off points, WHR is the most useful measure of obesity to use to identify individuals with CVD risk factors.

Adult↗
PubMed2000

Body mass index and alternative indices of obesity in relation to height, triceps skinfold and subsequent mortality: the Busselton health study.

OBJECTIVES: The ideal index for leanness and obesity in epidemiological studies should correlate strongly with body weight and with a direct measure of fat while minimizing the influence of height. The preferred index is expected to show meaningful associations with subsequent mortality. Our aims were to compare weight/height, weight/height(2) (body mass index or BMI), and weight/height(3) as candidates for this index. DESIGN: We analysed cross-sectional data from surveys of 6948 adults (3334 men (mean age 43 y, mean BMI 24.8 kg/m2), and 3614 women (mean age 42 y, mean BMI 24.3 kg/m2)) in Busselton, Australia whose weight, height, triceps skinfold, and cardiovascular risk factors were measured from 1966 through to 1978. In these same subjects we studied the mortality risks of indices of obesity using Cox regression analysis for survival time from first survey to death, or to follow up at the end of December 1995, after adjustment for age. Subjects dying within 5 y of the baseline survey were excluded from the analysis to avoid the bias of concurrent illness. We also studied subgroups including never smokers, subjects with no heart disease, and subjects <60 years of age at first survey. RESULTS: In men, weight/height2 met the criteria for a satisfactory index in that there was a very strong correlation with triceps skinfold, and a negligible correlation with height. For women, weight/height was as good a measure as weight/height2, with both having strong correlations with triceps skinfold, and minimal correlations with height. Weight/height2 as a predictor of mortality in men of all ages showed the typical U-shaped associations that were similar and consistent and of variable statistical significance. The significances of the hazard ratio curves were the strongest for cardiovascular disease deaths (all men P=0.001; men without heart disease at baseline P<0.001; never smoking men P=0.007). In never smoking men there was a near linear positive relationship with all-cause mortality (P=0.018). In women weight/height2 showed no consistent associations with mortality. There was a shallow U-shaped relationship with all-cause mortality (P=0.087), also seen in never smoking women (P=0.075). In assessing 'ideal' weight for height in this population, a weight/height2 of 25 kg/m2 (range 22.5-27.5 kg/m2) is appropriate. Weight/height and mortality showed very similar patterns in men to weight/height2 with quite similar levels of statistical significance. In women much more pronounced U-shaped curves were apparent in all groups and subgroups, with a significant all-cause mortality trend for all women (P=0.029) and never smoking women (P=0.034). In assessing 'ideal' weight for height a weight/height of 42.5 kg/m (range 35-50 kg/m) appears appropriate for men and women. CONCLUSIONS: Weight/height2 is an appropriate index of leanness and obesity in males at all ages, whereas weight/height is at least as good an index for females. In mortality studies weight/height2 and weight/height predict mortality similarly in males, but weight/height is a better discriminant of mortality in females. International Journal of Obesity (2000)24, 108-115

Adult↗
PubMed1999

New classification and criteria for diagnosis of diabetes mellitus. The Australasian Working Party on Diagnostic Criteria for Diabetes Mellitus.

Diagnosis of diabetes is not in doubt when there are classical symptoms of thirst and polyuria and a random venous plasma glucose level > or =11.1 mmol/L. The Australasian Working Party on Diagnostic Criteria for Diabetes Mellitus recommends: Immediate adoption of the new criterion for diagnosis of diabetes as proposed by the American Diabetes Association (ADA) and the World Health Organization (WHO) - fasting venous plasma glucose level > or =7.0 mmol/L; Immediate adoption of the new classification for diabetes mellitus proposed by the ADA and WHO, which comprises four aetiological types - type 1, type 2, other specific types and gestational diabetes - with impaired glucose tolerance and impaired fasting glycaemia as stages in the natural history of disordered carbohydrate metabolism; Awareness that some cases of diabetes will be missed unless an oral glucose tolerance test (OGTT) is performed. If there is any suspicion or other risk factor suggesting glucose intolerance, the OGTT should continue to be used pending the final WHO recommendation.

Blood Glucose↗
PubMed1997

Australian Diabetes Screening Study: impaired glucose tolerance and non-insulin-dependent diabetes mellitus.

In preventing non-insulin-dependent diabetes mellitus (NIDDM) and its complications, screening high-risk individuals complements public health measures. Our screening instrument for patients of general practitioners was a questionnaire for self-determined high-risk groups plus a laboratory measurement of a random venous plasma glucose level. Collaborating practitioners evaluated 100 consecutive outpatients aged 40 years or older. The questionnaire identified patients with two or more diabetic symptoms or with two or more risk factors, and they were recommended to have their blood tested. For those with a random plasma glucose greater than 5.5 mmol/L, oral glucose tolerance tests (OGTTs) were advised. Of 50,859 subjects completing the study, there were 1,013 cases (2.0%) of new diabetes, 1,704 cases (3.4%) of impaired glucose tolerance (IGT), and 5,508 cases (10.8%) of previously diagnosed diabetes. Symptoms alone were a relatively poor discriminant. Almost all newly identified NIDDM and IGT patients had two or more risk factors for NIDDM. The risk ratios for abnormal glucose tolerance were as follows: high blood pressure, 2.4; overweight, 2.0; and positive family history, 1.7. Selection of cutoff points higher than 5.5 mmol/L would have substantially reduced the rate of newly discovered NIDDM and IGT. Screening for NIDDM and IGT in general practice is feasible and can be achieved with little disruption of office procedures. In preventive programs of this nature, the low screening threshold of 5.5 mmol/L for random venous plasma glucose maximizes the case-finding rate.

Adult↗
PubMed1996

Spouse correlations in cardiovascular risk factors and the effect of marriage duration.

Spouse correlations in cardiovascular risk factors were investigated using data on 2,836 spouse pairs collected in the Busselton Population Health Surveys over the period 1966-1981. The risk factors considered were systolic blood pressure, diastolic blood pressure, body mass index, triceps fatfold, cholesterol, and forced expiratory volume (1 second). Statistically significant positive correlations (p < 0.01) were found for all (age-adjusted) variables. There was a statistically significant decreasing trend in the correlations for systolic blood pressure with marriage duration (trend p < 0.01). Although no other variables showed statistically significant trends, the correlations for diastolic blood pressure (p = 0.29), body mass index (p = 0.14), and forced expiratory volume (p = 0.16) also decreased with marriage duration, and correlations for cholesterol (p = 0.61) and triceps fatfold (p = 0.99) increased with marriage duration. These results suggest that there is spousal concordance in cardiovascular risk factors. The lack of consistent increasing trends in the correlations with marriage duration suggests that assortative mating may be a more likely explanation than the sharing of a common environment.

Adult↗
PubMed1996

Familial correlations, cohabitation effects, and heritability for cardiovascular risk factors.

Familial correlations in cardiovascular risk factors were investigated with use of data from a community-based sample of 1319 nuclear families involving 4178 adult persons collected in the Busselton Population Health Surveys over the period 1966 to 1981. The risk factors considered were systolic blood pressure, diastolic blood pressure, body mass index, triceps fatfold, and cholesterol. All risk factors showed positive familial correlations, with correlations generally being lower for spouses than for parent-offspring pairs or for siblings. Spouse correlations showed little variation with age, suggesting that observed correlations are primarily due to assortative mating and not to cohabitation. The parent-offspring correlations tended to decline with age of (adult) offspring; this observation suggests that the effect of a shared household environment during childhood and adolescence diminishes over time when living apart during adulthood. The sibling correlations decreased with age for blood pressure and serum cholesterol and increased with age for body mass index and triceps fatfold. The estimated heritabilities were 27% for systolic and diastolic blood pressure, 37% for serum cholesterol, 52% for body mass index, and 23% for triceps fatfold. These results confirm that substantial familial aggregation of cardiovascular risk factors occurs and that much of this aggregation has a genetic basis, although assortative mating (in spouses) and environmental influences (in offspring and siblings) are also present. The nuclear family should be considered as a point of intervention in cardiovascular disease prevention programs.

Adult↗
PubMed1996

Self-reported health and use of health services: a comparison of diabetic and nondiabetic persons from a national sample.

Population-based epidemiological and health service utilisation information on diabetes and other noncommunicable diseases is still scarce in Australia. Such information is needed by health economists, policy makers and service providers. Data from the 1989-90 National Health Survey conducted by the Australian Bureau of Statistics have been used to obtain estimates of the prevalence of cardiovascular morbidity, life-style factors, use of hospital and medical services, and self-assessed health and happiness for Australian persons with diabetes. Prevalences are compared with those for persons without diabetes. Those with diabetes had two to three times the prevalence of most cardiovascular conditions, similar levels of exercise (except for diabetic women over 40 years of age who exercised less than their nondiabetic counterparts), lower levels of alcohol consumption (except for younger men, who had a similar frequency of heavy drinking as their nondiabetic peers), similar levels of smoking, a higher prevalence of overweight, and significantly greater frequency of hospital admissions, use of outpatient services and general practitioner consultations. About half of the people with diabetes assessed their health as good or excellent but 90 per cent stated that they were happy or very happy. No differences between diabetic people living in capital cities and other areas were found. These results have implications for education and life-style behaviour modification programs for people with diabetes. Research into the prevention and more effective management of diabetes and its complications is required in order to contain the escalating health care burden associated with diabetes in Australia.

Adolescent↗
PubMed1995

1989-90 National Health Survey: prevalence of self-reported diabetes in Australia.

OBJECTIVE: To estimate the prevalence of self-reported diabetes in a representative population sample in Australia; to identify major differences in prevalence by State and Territory and by geographic origin; and to compare trends in prevalence over time. DESIGN: and setting: Analysis of data collected by the Australian Bureau of Statistics in the 1989-90 National Health Survey. The sampling frame (22,202 households and 54,241 people) ensured adequate representation from each State and Territory in Australia. RESULTS: Prevalences of self-reported diabetes/high blood sugar levels were 1.9% for males and 2.0% for females over all ages; 3.1% for men and 2.9% for women aged over 25 years; and 8.1% for men and 6.9% for women aged over 65 years. Interstate differences of borderline significance were found and will require validation in larger samples. Age-standardised prevalences were higher in subjects born in Southern Europe and lower in those born in Western Europe compared with Australian-born subjects. Prevalences were high in households where the language spoken was other than English. The frequency of self-reported diabetes appears to be rising. CONCLUSIONS: Australia has comparatively low total prevalences of self-reported diabetes/high blood sugar levels. High prevalences subsections exist, including the elderly and certain migrant groups

Adolescent↗
PubMed1995

Age and secular trends in risk factors for cardiovascular disease in Busselton.

Mortality rates from heart disease and stroke in Australia have been falling for more than 20 years. No completely satisfactory explanations for this trend exist. However, it is believed to be due, at least in part, to changes in the incidence of cardiovascular disease arising from changes in the prevalence and severity of risk factors for cardiovascular disease. The adult community of Busselton in Western Australia participated in cross-sectional health surveys every three years from 1966 to 1981. This paper describes secular trends from 1966 to 1981 and age trends from 25 to 80 years for cardiovascular risk factors in Busselton men and women. Downwards secular trends were observed for mean blood pressure and smoking for men and women, upwards trends were observed for body mass index in men, and mean cholesterol was approximately constant over this period. The age and secular trends were consistent with other Australian studies conducted in the 1980s and with overseas studies. An estimated 67 per cent of the decline in cardiovascular mortality rates among Busselton men and 22 per cent of the decline among Busselton women may be attributed to changes in the prevalence of risk factors for cardiovascular disease.

Adult↗