Use of self-report to monitor overweight and obesity in populations: some issues for consideration

OBJECTIVE

To examine the validity of self-reported height and weight data reported over the telephone in the 1997 NSW Health Survey, and to determine its accuracy to monitor overweight and obesity in population surveys.

METHOD

Self-reported and measured heights and weights were collected from 227 people living in Western Sydney, who had participated in the NSW Health Survey 1997.

RESULTS

Self-reported (SR) weights and heights led to misclassification of relative weight status. BMI, based on measured weights and heights, classified 62% of males and 47% of females as overweight or obese, compared with 39% and 32%, respectively, from self-report.

CONCLUSIONS

Caution should be used when interpreting SR height and weight data from surveys, because BMI derived from these is likely to underestimate the true prevalence of overweight and obesity.

IMPLICATIONS

SR data have a place in nutrition monitoring because they are relatively inexpensive and easy to collect. However, classifying people into weight categories on the basis of accepted cut-points, using SR heights and weights, yields inaccurate prevalence estimates. Periodic sub-studies of the validity of SR heights and weights are needed to indicate the extent to which the validity of SR is changing.

Dental service provision in private general practice for an insured population in New South Wales, Australia

OBJECTIVE

To determine patterns of dental services provided to a cohort of the insured population 18 years and over, in private general practice in New South Wales, Australia.

BASIC RESEARCH DESIGN

A cohort study using the person-years method and Poisson regression for analysis.

SETTING

Data were derived from claims records submitted by members of a health insurance fund (Government Employees Health Fund-GEHF) for rebates during the study period 1 January 1992-31 December 1995.

PARTICIPANTS

There were 133,467 members aged 18 years and over from New South Wales.

MAIN OUTCOME MEASURES

To determine, by age group, for those members who used private general practice and made a claim (referred to as 'patients') the annual number of visits, total number of services received per year and number of services received at a visit.

RESULTS

The mean number of visits per patient was 2.4 per year with patients under 45 years making fewer visits than the 45-54 age group reference category. Mean number of services utilised per patient-year was 5.9, with services provided increasing from 3.5 for the 18-24-year-old group, reaching a plateau of approximately 6.2 for those aged 45 years or more. The number of services received per visit was 2.4 and there were no differences by age. Service mix was dominated by restorative (35%), diagnostic (27%), and preventive services (18%); with age specific variations observed.

CONCLUSIONS

Age was found to be an important determinant in the use of dental services, independent of membership duration and gender.

Prevalence and socio-demographic predictors of dietary goal attainment in an older population

OBJECTIVE

To describe the measured dietary intakes and anthropometry of a large, free-living population of middle-aged and older Australians who participated in the Australian Blue Mountains Eye Study (BMES), and to identify the socio-demographic characteristics associated with attainment or non-attainment of dietary goals.

METHOD

Anthropometry and dietary intakes were compared with current population dietary goals and Recommended Dietary Intakes for 2,873 people (79% of eligible residents) aged > or = 49 years who participated in the BMES. Nutrient intakes were measured by a validated food frequency questionnaire.

RESULTS

Nutrients for which mean intakes deviated most from nutrition goals included: percentages of energy from total and saturated fat, carbohydrate and alcohol (men), as well as absolute intakes of calcium, zinc and fibre. More than half the men (60%) and women (54%) were overweight or obese. Several micro-nutrient goals were more likely to be met in households where the respondents and/or their spouses were independent. Married men were more likely to meet goals for fibre and iron, but less likely to meet the goal for cholesterol. Several goals were more likely to be met by men and women who had qualifications after leaving school, those with higher job status and non-pensioners, suggesting an socio-economic status dimension.

CONCLUSIONS AND IMPLICATIONS

These results indicate that over- rather than under-nutrition is more prevalent among community-dwelling older people, although under-nutrition should not be overlooked. Particular sub-groups that are less likely to meet some dietary goals may require targeting in community nutrition interventions.

Carrots, carotene and seeing in the dark

Should older people eat more carrots, or at least increase their carotene intake to prevent loss of night vision? Participants in the Blue Mountains Eye Study were asked about their ability to see in the dark. Nutrient and food intake were estimated from a food frequency questionnaire. Associations between self-reported poor night vision and estimated nutrient intake were investigated using logistic regression. Poor night vision among women was associated with higher beta-carotene (P for trend = 0.03) and total vitamin A intake (P for trend = 0.048). Increased consumption of carrots, but no other food high in beta-carotene, was associated with significant increased reporting of poor night vision among women (P for trend = 0.04). While carrot intake may protect against difficulty in seeing at night, it is probable that people attributing poor driving ability to their vision may be eating more carrots in the hope of reversing this decline.

Sociodemographic distribution of measures of body fatness among children and adolescents in New South Wales, Australia

BACKGROUND

Obesity in childhood and adolescence is associated with health problems, increases in cardiovascular disease (CVD) risk factors and a greater likelihood of becoming overweight as an adult. A description of the sociodemographic distribution of overweight and obesity among children and adolescents in the population may allow us to determine if health promotion resources should be differentially allocated to particular groups.

METHODS

The New South Wales Schools Fitness and Physical Activity Survey, 1997 (n = 5518) was a cross-sectional survey which measured height, weight, waist and hip girths and skinfold thicknesses of randomly selected New South Wales students in school years 4, 6, 8 and 10. Height and weight only were measured among Year 2 students. The mean ages of students in school years 2, 4, 6, 8 and 10 were 7.3y, 9.3y, 11.3y, 13.3y and 15.3y, respectively. The values of body mass index (BMI), waist girth, waist-to-hip ratio (WHR) and sum of three skinfolds for students resident in urban and rural areas and in tertiles of socioeconomic status (SES) were compared.

RESULTS

There were no differences on any of the anthropometric measures between urban and rural boys and girls, with the exception that WHR was higher among urban girls. Among boys, there were no differences between the SES tertiles on any of the measures. Among girls, each of the anthropometric measures (except sum of skinfolds) was inversely associated with SES, with body fatness tending to be lower in the high SES tertile, compared with the low and middle SES tertiles. None of the statistical interactions between school year and body fatness was significant, suggesting that the relationship is consistent from childhood to adolescence.

CONCLUSION

On the basis of these results, we suggest that health promotion programs aimed at weight management among Australian girls of lower SES are not warranted. We recommend that health promotion programs emphasize regular physical activity, a healthy diet and acceptance of the normal range of body shapes.

The impact of work related trauma on the psychological health of nursing staff: a cross sectional study

This study aims to investigate the effects of work-related trauma exposure on the health of nursing staff in hospitals. The survey was conducted using a randomised sample of 314 nurses. Half (52.2%, n = 189) of staff surveyed had multiple exposures to different kinds of trauma. Results on the General Health Questionnaire (GHQ) and Beck's Depression Inventory--Revised (BDI-R) suggested that nearly 40% of staff experienced poor health, while nearly 10% experienced moderate to severe depression. Results of the logistic analyses, after adjusting for confounders, suggested that high and long term trauma exposure is detrimental to the mental health of nurses. These findings indicate that hospital nursing staff, in particular those who have high exposure to trauma, are in urgent need of support services such as debriefing and counselling.

Interobserver reliability of the click test: a rapid bedside test to determine surfactant function

OBJECTIVE

To determine the interobserver reliability of the click test, a rapid bedside test of surfactant function.

METHODOLOGY

One hundred samples (48 amniotic fluid, 28 gastric aspirates, 24 tracheal aspirates) were obtained from pregnant women, term and preterm infants managed at two perinatal centres. Gestational ages of the pregnancies or infants at time of sampling ranged from 24 to 40 weeks (mean +/- s.d.: 31+/-5). The click test was performed independently by two observers, with differing levels of experience, and blinded to each other's results. Interobserver reliability was determined for samples classified as negative (no clicking bubbles), equivocal (a few clicking bubbles seen after 2 min of looking), and positive (clicking bubbles seen easily on first look). As negative and equivocal test results suggest surfactant dysfunction, these results were also combined to provide a dichotomised result.

RESULTS

For samples classified as negative, equivocal and positive the interobserver agreement was 0.83, with agreement beyond chance shown by a quadratic weighted Kappa of 0.74 (95% CI = 0.62-0.86). When negative and equivocal results were combined, the simple Kappa was 0.73 (95% CI = 0.59-0.87).

CONCLUSIONS

The click test has a high level of interobserver reliability. It is rapid, simple, accurate and able to be taught to medical and nursing staff with appropriate training. It has many potential applications including the prediction of fetal lung maturity in women with premature rupture of membranes, and in term and preterm infants who require the bedside testing of surfactant function.

Baseline ventilatory function predicts the development of higher levels of fasting insulin and fasting insulin resistance index: the Normative Aging Study

A consistent but as yet unexplained association between baseline ventilatory function and risk of coronary heart disease (CHD) has been reported from many prospective studies. Insulin-resistant states are associated with increased risk of CHD. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and maximal mid-expiratory flow rate (MMEF) at study entry were examined as predictors for indirect measures of insulin resistance after a mean follow-up interval of 20.9 yrs in 1050 nondiabetic male subjects in the Normative Aging Study. Males in the top quintile of insulin or fasting insulin resistance index (FIRI) levels at follow-up were defined as being relatively insulin resistant. FVC was negatively associated with risk of being relatively insulin resistant using the insulin (p=0.002) or FIRI (p=0.0001) criteria at follow-up in logistic regression models adjusting for baseline age, body mass index, fat distribution pattern and cigarette smoking. Similar associations were found for FEV1 and MMEF. Additional adjustment for baseline postcarbohydrate challenge glucose levels made little difference to the results, suggesting that baseline glucose intolerance was not a significant source of bias. These findings are consistent with the possibility that insulin resistance may be one of the factors mediating the previously unexplained prospective association between impairment of ventilatory function and risk of mortality from coronary heart disease.

Impaired ventilatory function and elevated insulin levels in nondiabetic males: the Normative Aging Study

Lower levels of baseline ventilatory function have consistently been associated with increased risk of cardiovascular mortality in prospective studies, but the underlying mechanisms are not known. Increased risk of coronary heart disease is associated with higher serum insulin levels. This report examines the relationship between ventilatory function and indirect measures of insulin resistance. Cross-sectional data from 922 nondiabetic participants in the Normative Aging Study were analysed using multiple linear regression models with adjustment for potential confounders. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were examined in relation to indicators of insulin resistance, i.e. fasting insulin and the fasting insulin resistance index (FIRI). Diabetics were excluded because impaired insulin secretion interferes with the validity of these as measures of insulin resistance. Fasting insulin and FIRI were negatively correlated with FVC and FEV1 (all p< 0.001). These associations persisted after adjusting for potential confounders including age, height, body mass index, waist to hip circumference ratio, physical activity, alcohol intake and smoking in separate multiple linear regression models, for both insulin (all p< or =0.0008) and FIRI (all p< or =0.0001). Negative cross-sectional associations between ventilatory function and indirect measures of insulin resistance were found in nondiabetic males. Insulin resistance may contribute to the previously unexplained association between ventilatory function impairment and cardiovascular mortality. Mechanisms underlying the relationship between insulin resistance and decreased ventilatory function remain to be elucidated.

Effects of body composition and fat distribution on ventilatory function in adults

Clinically, gross obesity is associated with disturbances of ventilatory function, but less severe obesity is not generally thought to have a significant effect on ventilatory function. The purpose of this report was to examine cross-sectional data to determine the effects of body composition and fat distribution on ventilatory function in 1235 adults (621 men and 614 women). Forced vital capacity (FVC) was used as a measure of ventilatory function and was adjusted for age, height, smoking, and bronchial symptoms in separate models for men and women. Body fat and fat-free mass were estimated from skinfold-thickness measurements. Adjusted FVC was not significantly associated with body mass or body mass index, but was negatively associated with percentage body fat in men (P = 0.0003) and women (P = 0.043) and positively associated with fat-free mass in men (P = 0.018) and women (P = 0.0001). Handgrip strength was positively associated with adjusted FVC in both sexes (P < 0.02), suggesting that the effect of fat-free mass may be mediated by muscular strength. Adjusted FVC was negatively associated with subscapular-skinfold thickness in both sexes (P < 0.0003) and with waist circumference (P = 0.01) and waist-to-hip ratio (P = 0.03) in men. Previous reports that considered only body mass index or body mass failed to distinguish the opposing effects of fat-free mass and fat mass on FVC.

Cohort study of vitamin C intake and cognitive impairment

To test the hypothesis that vitamin C protects against cognitive impairment, the authors conducted a cohort study (n=117) in a retirement community in Sydney, Australia. Vitamin C intake was assessed at baseline (1991) with a semiquantitative food frequency questionnaire, and cognitive function was assessed 4 years later (1995). After adjustment for age, sex, smoking, education, total energy intake, and use of psychotropic medications, consumption of vitamin C supplements was associated with a lower prevalence of more severe cognitive impairment (based on scores on the Mini-Mental State Examination; adjusted odds ratio=0.39, 95% confidence interval 0.18-0.84). There were no associations between vitamin C intake and scores on tests of verbal and category fluency. This study suggests that vitamin C might protect against cognitive impairment.

Temporal relations between obesity and insulin: longitudinal data from the Normative Aging Study

Although obesity and insulin levels are generally associated in cross-sectional data, the temporal and causal nature of their association is not yet clear. Increased obesity may have preceded increased insulin levels or vice versa. The authors examined the temporal relations between fasting insulin blood levels and weight in longitudinal data from the ongoing Normative Aging Study. Two insulin measurements from which a rate of change (delta Insulin) could be calculated were available from 376 non-diabetic male subjects (mean age = 62.1 years). Rate of change in weight could be calculated for the previous inter-examination period (delta Weight1), the contemporaneous period (delta Weight2), and the inter-examination period following the second insulin measurement (delta Weight3). delta Weight2 was a significant predictor (p = 0.0005) of delta insulin in multiple linear regression models that included control for potential confounders (body mass index, waist-to-hip ratio, antihypertensive and diuretic medication use, and age) and for correlation between the initial level and change in insulin (mean fasting insulin). delta Weight1 was added to the model and was found not to be statistically significant (p = 0.15). When the model was stratified by age tertile, the regression coefficient on delta Weight1 was -0.44 (p = 0.018) for the youngest stratum, -0.06 (p = 0.72) for the middle stratum, and 0.21 (p = 0.19) for the oldest men. Similarly, delta Insulin was a significant predictor of delta Weight3 (p = 0.026) in a separate regression model. These findings are consistent with both possible temporal sequences of association between changes in insulin and obesity. The intricate homeostatic mechanisms that regulate changes in insulin and obesity may not be readily amenable to description in terms of cause and effect.

Hematological indices in an older population sample: derivation of healthy reference values

Factors affecting hematological values were explored, and healthy reference values were estimated from a cross-sectional survey of a population (n = 4433), ages 49 years or more, residing permanently in a defined geographic region. Nursing home residents were excluded. Details of medication use and medical history were obtained by interview, and participants were asked to return after an overnight fast for blood sampling. The participation rate was 82.4%, of whom 88.4% provided a fasting blood sample. Hemoglobin, hematocrit, and erythrocyte counts were higher in men, whereas platelet counts were higher in women. Statistical associations between each hematological index and smoking, alcohol intake, use of certain drugs, chronic disease, and high creatinine values were tested by unpaired t-tests. Separate reference groups were defined for each hematological index by excluding subjects with any of the factors found to be of importance. The resulting reference values are particularly appropriate for evaluating hematological test results in older individuals.

Effects of body fat on ventilatory function in children and adolescents: cross-sectional findings from a random population sample of school children

Childhood obesity is associated with a range of adverse consequences, and the prevalence is increasing in developed nations. Most of the literature on obesity and ventilatory function in children concerns samples selected for gross obesity with relatively little detail available from random population samples. This report examines the effect of total body fat as a percentage of weight (TBF%) on ventilatory function in a nationally representative sample of 2,464 Australian school children aged 9, 12, and 15 years. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were used as measures of ventilatory function. TBF% was estimated from skinfold thickness measurements. Ventilatory function was adjusted (for height and then for both height and weight) using linear regression on a logarithmic scale. Adjustment was performed within separate strata of age and gender. Analysis of covariance was used for hypothesis testing. Height-adjusted FVC and FEV1 values increased significantly with increasing weight within each age and gender group and for all subjects combined (P < 0.0001). The effect of TBF% independent of lean tissue was examined using FVC and FEV1 values adjusted for both height and weight, because body weight measures both lean and fat mass. Adjusted FVC and FEV1 values decreased significantly with increasing TBF% within each age and gender group and for all subjects combined (P < 0.0001). Ventilatory function decreased with increasing proportions of body fat. This is consistent with previous findings on lean tissue mass and ventilatory function. Although the magnitude of the effect was relatively small in clinical terms, from a public health perspective our findings indicate yet another adverse consequence of childhood obesity.

Handgrip strength and insulin levels: cross-sectional and prospective associations in the Normative Aging Study

Hyperinsulinemia is associated with insulin resistance and with the development of diabetes, hypertension, and coronary heart disease. Physical activity appears to be negatively associated with insulin resistance, although the mechanism is unclear. The relationship between physical activity and insulin resistance could be mediated, in part, by direct effects on skeletal muscle, a significant site for insulin-mediated glucose disposal. This report examines the relationship between skeletal muscle strength (as measured by handgrip dynamometry) and fasting insulin levels in a cohort of men in the ongoing Normative Aging Study (NAS). Handgrip strength was negatively associated (P = .013) with logarithmic (log) fasting insulin in cross-sectional data from 655 subjects after adjustment for potential confounders including age, body mass index (BMI), ratio of abdominal girth to hip breadth (AG/HB), usual physical activity level, and alcohol intake in a multiple regression model. In data collected prospectively among 1,195 subjects, handgrip strength measured at study entry was negatively predictive of log fasting insulin (P = .017) measured 22.9 +/- 2.6 years later, after adjustment for age, BMI, and AG/HB at study entry in a multiple linear regression model. A cross-sectional association was confirmed in an analysis of prospective data on the relationship between handgrip strength and fasting insulin levels. The findings suggest that skeletal muscle weakness may precede and predict the development of insulin resistance, and raise the intriguing possibility of some common cause in skeletal muscle pathophysiology.

Effects of body fat on ventilatory function in children and adolescents: cross-sectional findings from a random population sample of school children

Childhood obesity is associated with a range of adverse consequences, and the prevalence is increasing in developed nations. Most of the literature on obesity and ventilatory function in children concerns samples selected for gross obesity with relatively little detail available from random population samples. This report examines the effect of total body fat as a percentage of weight (TBF%) on ventilatory function in a nationally representative sample of 2,464 Australian school children aged 9, 12, and 15 years. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were used as measures of ventilatory function. TBF% was estimated from skinfold thickness measurements. Ventilatory function was adjusted (for height and then for both height and weight) using linear regression on a logarithmic scale. Adjustment was performed within separate strata of age and gender. Analysis of covariance was used for hypothesis testing. Height-adjusted FVC and FEV1 values increased significantly with increasing weight within each age and gender group and for all subjects combined (P < 0.0001). The effect of TBF% independent of lean tissue was examined using FVC and FEV1 values adjusted for both height and weight, because body weight measures both lean and fat mass. Adjusted FVC and FEV1 values decreased significantly with increasing TBF% within each age and gender group and for all subjects combined (P < 0.0001). Ventilatory function decreased with increasing proportions of body fat. This is consistent with previous findings on lean tissue mass and ventilatory function. Although the magnitude of the effect was relatively small in clinical terms, from a public health perspective our findings indicate yet another adverse consequence of childhood obesity.

Burden and outcomes of hospitalisation for congestive heart failure

OBJECTIVE

To describe the hospital burden and health outcomes associated with admission for congestive heart failure (CHF).

DESIGN AND SETTING

Descriptive follow-up study in a tertiary-level metropolitan teaching hospital.

PATIENTS

Acute adult inpatients with a clinical diagnosis of CHF for more than 24 hours admitted to Westmead Hospital, Sydney, during the four months from September 1993 to January 1994. At baseline, 122 patients were assessed; 88 patients were assessed at four-month follow-up.

INTERVENTIONS

Usual clinical care.

MAIN OUTCOME MEASURES

Length of stay; hospital bed-days; readmissions; mortality; health related quality of life (SF-36); patient knowledge.

RESULTS

The average age of subjects was 73.4 years. Many were using informal domiciliary care before admission. Mean length of stay for the baseline admission was 13.8 days, accounting for 7.6% of hospital separations and 1683 hospital bed-days, or 4.2% of bed-days for all inpatients aged 65 years and over. Fifteen patients were readmitted for CHF during the following four months, with a total of 26 CHF-related admissions. Twenty-one patients (17.2%) died during the course of the study. Quality of life at baseline was poor compared with population normative data, with a slight improvement among survivors at four-month follow-up. Patient knowledge of CHF was poor in a subsample survey (n = 24).

CONCLUSIONS

CHF represents a significant burden to patients (through morbidity and mortality), their carers (through provision of daily care), and hospitals (through multiple admissions for acute decompensation). It is difficult to monitor the hospital burden of CHF using routine data sources.

Alcohol intake and insulin levels. The Normative Aging Study

Much remains to be clarified in the apparently protective effect of moderate alcohol use against coronary heart disease risk. Insulin levels are positively associated with coronary heart disease risk, so recent reports of decreased insulin sensitivity among nondrinkers and lower fasting insulin levels with increasing alcohol intake suggest the possibility that insulin may play a role. Between 1987 and 1991, the authors examined fasting insulin concentrations and the empiric fasting insulin resistance index in relation to reported alcohol intake (mean, 15.3 g/day; standard deviation, 19.6; range, 0-120.6) and potential confounders. The latter included age, obesity, fat distribution, smoking, energy, saturated fat intake, antihypertensive medication, and physical activity. Participants in this cross-sectional analysis were 938 nondiabetic men from the Boston, Massachusetts, area who were part of the Normative Aging Study. Unadjusted fasting insulin levels were significantly different (p = 0.008) between categories of alcohol intake, as were fasting insulin resistance index values (p = 0.01). After adjustment for potential confounders, analysis revealed that subjects consuming moderate amounts of alcohol had the lowest fasting insulin and fasting insulin resistance index values. Compared with values from moderate drinkers, fasting insulin resistance index values were higher in those subjects reporting no alcohol intake (p = 0.011), low intake (p = 0.004), and high intake (p = 0.04). A similar pattern was observed for fasting insulin values. Among this sample of nondiabetic men, moderate drinkers had the lowest levels of fasting insulin resistance index and fasting insulin, consistent with lower levels of insulin resistance and thus lower risk for coronary heart disease. These findings suggest the possibility that the coronary heart disease-protective effects of moderate alcohol use are at least partially mediated by insulin.

Effects of obesity and fat distribution on ventilatory function: the normative aging study

OBJECTIVE

Although the influence of obesity on ventilatory function has long been recognized, the nature of the relationship and the mechanisms are not yet clear. The purpose of this report was to examine the effects of overall obesity and fat distribution on ventilatory function.

METHODS

Multiple measurements over > 30 years from 507 subjects with lifelong tobacco consumption of < or = 1 pack-year were analyzed separately in five age decades from 30 to 79 years. FVC, FEV1, ratio of FEV1 to FVC, and maximal midexpiratory flow rate (MMEF) were each adjusted for age and stature. Relative adiposity (or obesity) was assessed using the body mass index (BMI). Subscapular skinfold thickness, abdominal girth, and the ratio of abdominal girth to hip breadth (AG/HB) were used as measures of body fat distribution. Multiple linear regression was used to explore the effects of overall adiposity and body fat distribution on ventilatory function.

RESULTS

BMI was positively associated with the ratio of FEV1 to FVC at all ages (p < 0.01), and negatively with FVC and MMEF between 40 and 69 years (p < 0.01). After adjustment for BMI, subscapular skinfold thickness was negatively associated with both FVC and FEV1 (p < or = 0.02) among men aged 30 to 59 years, whereas AG/HB was negatively associated with FVC and FEV1 in men aged 50 to 59 years only (p < or = 0.0004).

CONCLUSIONS

Body fat distribution has independent effects on ventilatory function after adjustment for overall obesity in men. The finding that age modifies this association has implications for future research.

Adiposity and body mass indices in children: Benn's index and other weight for height indices as measures of relative adiposity

OBJECTIVES

Several forms of weight for height or body mass index (BMI) are in widespread epidemiological and clinical use as measures of relative adiposity. The form derived by Benn for adults has been advocated for use in children and practical aspects of this proposition are considered.

METHODS

Height and weight data from 8492 Australian schoolchildren aged 7 to 15 were studied. A subsample of 2753 children aged 9, 12 and 15 years had skinfold thicknesses measured. The sum of four skinfolds and percentage body fat predicted from skinfolds were used as measures of adiposity.

RESULTS

Of the various forms of power type BMI examined, weight/(height)2 was most closely associated with adiposity in this sample. Benn's assumption of low correlation between height and adiposity (which holds in adults) was not satisfied in children.

CONCLUSIONS

Benn's index is not recommended for general use as a body mass index in children. However, Benn's relative weight has advantages as an indirect measure of adiposity which may be of value in epidemiological studies among children.

Body mass index in screening for adiposity in children and adolescents: systematic evaluation using receiver operating characteristic curves

Body mass index (BMI) has been recommended for use in adolescent screening programs to select subjects with excess body fat for appropriate interventions. No systematic evaluation of MBI in screening for high degrees of adiposity was available when these recommendations were formulated. The purpose of this paper was to evaluated the screening performance of BMI using appropriate epidemiologic methods. Percentage body fat (TBF%) was measured by dual-energy X-ray absorptiometry DXA) in a convenience sample of 230 (119 males, 111 females) health Australian volunteers aged 4-20 y inclusive. Receiver operating characteristic (ROC) curves were prepared for detecting TBF% at or beyond the 85th percentile, using BMI as the screening test. Screening performance was slightly better for girls than for boys, but the differences were not significant. Reasonable true-positive (0.71, 95% CI: 0.53, 0.85) and low false-positive (0.05, 95% CI: 0.02, 0.09) rates were observed at the 85th percentile cutpoint for BMI. At the 95th percentile cutpoint for BMI, both true-positive (0.29, 95% CI: 0.15, 0.47) and false-positive (0.01, 95% CI: 0.00, 0.03) rates were lower. Screening for excess adiposity by using an appropriate percentile cutoff for BMI gives acceptable performance. ROC curves facilitate design of screening programs by allowing an explicit tradeoff between true-positive and false-positive rates. Although large sample sizes are required for precise estimates, the cutoff points that have been recommended appear to offer a reasonable compromise between true-and false-positive rates.

Recommended body mass index cutoff values for overweight screening programmes in Australian children and adolescents: comparisons with North American values

OBJECTIVE

Guidelines for screening children and adolescents for overweight have recently been published by a North American Expert Committee. As Australian clinicians might uncritically adopt these recommendations, we explore the consequences of applying North American body mass index (BMI) cutoff values to an Australian population.

METHODOLOGY

The Australian BMI cutoffs were calculated using the methods recommended from height and weight data for 8492 schoolchildren aged 7-15 years old.

RESULTS

Smoothed Australian BMI cutoffs were similar to those derived from the first United States National Health and Nutrition Examination Survey (NHANES-I) values for whites. However, the NHANES-I cutoffs would result in systematic misclassification. Among 7 year olds, the NHANES-I 85th percentile cutoff would wrongly classify 4.6% of normal males and 9.1% of normal females as 'at risk of overweight'. At age 14 years, the NHANES-I 95th percentile cutoff would misclassify 3.5% of children as 'overweight' instead of 'at risk of overweight'.

CONCLUSION

Australian screening programmes should use BMI cutoffs appropriately derived from local measurements, and these are given for Australian children.

Social support, marital status and living arrangement correlates of cardiovascular disease risk factors in the elderly

Marital status and indices of social support are associated with mortality due to coronary heart disease and stroke. This association seems not entirely due to differences in recognised cardiovascular disease risk factors. The Western Sydney Stroke risk in the Elderly Study examined the relationship between marital status, living arrangements, widowhood and extent of social support, and risk factors for cardiovascular disease in men and women aged over 65 years. Unmarried men had the lowest mean HDL-C levels. Men living alone had the highest mean systolic blood pressures. The lower mean HDL-C levels and higher DBP levels seen among widows were not statistically significant after adjustment for differences in past medical history and education levels. The extent of social support was not associated with any significant differences in cardiovascular risk factor levels among men or women. We conclude that some of the increased risk of cardiovascular disease associated with socio-demographic factors among men in this age-group may be due to differences in primary cardiovascular disease risk factors. However, some of the mechanisms underlying risk of cardiovascular disease in this age-group remains obscure.

Repeatability of nutrient intakes estimated by a semiquantitative food frequency questionnaire in elderly subjects

In order to evaluate the repeatability of nutrient values estimated from a semiquantitative food frequency questionnaire being used in a longitudinal study of the relationships between diet, hemostatic factors, and stroke risk in the elderly in Western Sydney, a subsample of 62 participants (24 men, 38 women) completed a repeat questionnaire approximately 1 month after baseline data were collected. The mean age was 78 years (range, 65 to 88; median, 78). Nutrient values calculated from the repeat questionnaire were not significantly different from the baseline results by paired t test. Intraclass correlation coefficients ranged from 0.63 for beta carotene to 0.82 for saturated fat. Quadratic weighted kappa values were calculated for quintile categories and these ranged from 0.50 for fiber to 0.86 for ethanol. These values are comparable to previously published results in elderly subjects and confirm that repeatability of nutrient intakes estimated using semiquantitative food frequency questionnaires is very high in the elderly. Older subjects may be more established in their dietary habits than younger subjects, so any tendency for repeatability to decrease due to impaired memory associated with advanced age is offset by a lower intraindividual variability in dietary habit.

The Western Sydney Stroke Risk in the Elderly Study. A 5-year prospective study

Aging of the Australian population, as in other developed nations, will ensure that stroke remains one of the most important causes of death and disability. The Stroke Risk in the Elderly (SITE) study aims to measure prospectively the independent contribution of dietary, sociodemographic, blood lipid, blood pressure, and hemostatic factors to risk of stroke and other cardiovascular outcomes. The target population included all independently living men and women aged 65 years and over, residents in several retirement villages in western metropolitan Sydney, New South Wales, Australia. The study cohort consists of 225 men and 787 women, selected as a convenience sample from all eligible residents in the local government areas (LGAs) adjacent to Westmead Hospital. Participants attended a baseline session to complete dietary, life-style, medical, and sociodemographic questionnaires. Anthropomorphic variables and blood pressure were measured. Blood was taken for measurement of serum lipid, glucose, and hemostatic factors. Questionnaire results were compared with an age/sex-stratified, randomly selected sample drawn from the community (in the same LGAs), in order to quantify potential sampling and selection biases. The study cohort will be followed for a minimum of 5 years. The attendance rate of eligible residents for a baseline medical, dietary, life-style, and sociodemographic assessment was 72% for males and 69% for females. The study cohort was older, better educated, less ethnically diverse, and among women, less likely to have ever been married compared to people aged over 65 years in the comparison group. The baseline results suggest that hemostatic factors may be of importance in assessing risk of cardiovascular disease, (CVD), particularly in older men.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in serum lipids in Australian children: is diet responsible?

A total of 5211 schoolchildren aged 10-15 years participated in an Australia-wide sample survey conducted in 1985 and completed dietary and demographic assessment, and the measurement of body mass index: 1017 children aged 12 and 15 years gave blood for serum lipid analysis. Group mean differences in serum lipids and body mass index with age, sex, socioeconomic status and ethnic origin were determined. Nutritional analysis generated group mean values for daily energy intake, per cent kilo-joules from total fat, saturated fat, monosaturated fat and polyunsaturated fat, as well as the polyunsaturated:saturated fat ratio and nutrient density of fibre. In multiple regression analyses, socioeconomic and gender based differences in serum lipids could be explained by differences in diet, whereas age group differences could not. Although there were statistically significant differences in dietary fat intake on the basis of ethnic origin, these were not reflected in differences in serum lipids. For girls, dietary fat variables were more important predictors of serum lipids than body mass index. For boys, the reverse was true. These results suggest that class differences in cardiovascular risk arise from dietary differences that are present from an early age. Sex-based differences in serum lipids seem to reflect different mechanisms in girls and boys. In the former, dietary differences are of importance but for the latter, anthropomorphic (possibly exercise-linked) differences are the most important. These findings imply that cardiovascular risk preventive programmes for children need to take into account the mechanisms of social inequality and sex-based differences.

Clinical characteristics and outcomes in a cohort of patients who were assessed as in need of nursing-home care

A cohort of 116 applicants who were assessed by the Bundoora Extended Care Assessment Team during the first six months of 1985 as requiring nursing-home care was followed-up in an attempt to detect the clinical characteristics that were associated with a delay in placement. The demographic and clinical features of this cohort are described. By the end of the follow-up period, 89 applicants had been admitted to nursing homes. The mean time from assessment to placement for this group was 97.1 days. A significant delay in placement was associated with an age of less than 80 years, an inability to speak English, the presence of an indwelling urinary catheter, and the need for assistance with feeding. We concluded that some clinical characteristics had an effect on the time to placement among the nursing-home applicants who were assessed in the catchment area of our team.

Use of short stay beds by nursing home applicants waiting for placement

Implementation of the recent decision of the Commonwealth Department of Community Services and Health to set a uniform target ratio of 40 extensive care Nursing Home beds per 1000 persons aged 70 and over will result in substantial decreases in the availability of Nursing Home places in many Australian regions. The catchment area of the Bundoora Extended Care Assessment Team currently has a Nursing Home bed to population ratio which is very close to this target. It may serve as a model for the conditions likely to prevail when this target ratio is achieved in other Australian regions. Data from a cohort of 320 Nursing Home applicants from this catchment area assessed by the team suggests that at this level of Nursing Home bed provision, use of short stay institutional beds by applicants awaiting placement is substantial. Figures are provided which permit the estimation of short stay institutional bed use expected from regional populations where the level of nursing home bed provision is close to the CDCSH target.

Perspectives on nursing home placement--towards an analytical model

A simplified account of some of the factors affecting placement of elderly disabled applicants into nursing homes is presented. The placement process is described as the task of matching applicants from a waiting list to beds as these become available. Some recent data from one Victorian region is presented to illustrate the discussion. Although the number of waiting applicants at any one time (queue length) is only one measure of the overall situation, it is a convenient one to discuss. Factors affecting the length of the queue include the admission rate which is in turn related to the average length of stay. The potential for assessment-based admission controls to decrease the queue length by decreasing the number of long stay admissions is briefly discussed. Mechanisms for making the whole process more smooth and effective from the perspective of both the applicant and nursing home administration are reviewed.

Production of 2-Keto-L-Gulonate, an Intermediate in L-Ascorbate Synthesis, by a Genetically Modified Erwinia herbicola

A new metabolic pathway has been created in the microorganism Erwinia herbicola that gives it the ability to produce 2-keto-L-gulonic acid, an important intermediate in the synthesis of L-ascorbic acid. Initially, a Corynebacterium enzyme that could stereoselectively reduce 2,5-diketo-D-gluconic acid to 2-keto-L-gulonic acid was identified and purified. DNA probes based on amino acid sequence information from 2,5-diketo-D-gluconic acid reductase were then used to isolate the gene for this enzyme from a Corynebacterium genomic library. The 2,5-diketo-D-gluconic acid reductase coding region was fused to the Escherichia coli trp promoter and a synthetic ribosome binding site and was then introduced into E. herbicola on a multicopy plasmid. Erwinia herbicola naturally produces 2,5-diketo-D-gluconic acid via glucose oxidation, and when recombinant cells expressing the plasmid-encoded reductase were grown in the presence of glucose, 2-keto-L-gulonic acid was made and released into the culture medium. The data demonstrate the feasibility of creating novel in vivo routes for the synthesis of important specialty chemicals by combining useful metabolic traits from diverse sources in a single organism.

Immune interferon induces the receptor for monomeric IgG1 on human monocytic and myeloid cells

We report here that FcR for human monomeric IgG1 can be induced on cells of myeloid origin cultured in the presence of IFN gamma for 8 h. Supernatant fluids from cultures of lymphocytes infected with a variety of viruses or cocultured with cell lines have the same FcR enhancing effect as IFN gamma. We identify the factor in the supernatant fluid responsible for the induction as immune interferon. Among the different types of IFN, only the gamma type (both purified and recombinant) specifically induces the appearance of FcR for monomeric IgG1 on normal and leukemic myeloid cells but not on cells of lymphoid origin. This effect is also evident on mature PMN. We show that the specificity and the affinity of the receptor induced on HL-60 promyelocytic cells, peripheral blood monocytes, and PMN are identical to those of the receptor spontaneously present on the same cells, except for PMN, which do not spontaneously express this type of receptor. The results of inhibition experiments performed with mouse IgG of and IgG3. These results suggest that the receptor present on human monocytes different isotypes indicate that the receptor can be inhibited by murine IgG2a or immature myeloid cells, selectively inducible by IFN gamma, has a specificity similar to the FcR1 described on mouse macrophages.

Human natural killer cells analyzed by B73.1, a monoclonal antibody blocking Fc receptor functions. II. Studies of B73.1 antibody-antigen interaction on the lymphocyte membrane

In this paper, we characterize the antigen recognized by the monoclonal antibody B73.1 and the modification occurring at the membrane of the positive cells after interaction with the antibody. The B73.1-defined antigen is a protein of 50,000 to 72,000 daltons that is sensitive to pronase but not to trypsin treatment. B73.1 antibody, and its F(ab')2 fragment, directly block, at high concentrations, the binding of IgG antibody-sensitized erythrocytes to the Fc receptors (FcR) of a subpopulation of lymphocytes and neutrophils. B73.1 antibody dissociates rapidly from the positive cells, but concomitant modulation of both B73.1 antigen and FcR is induced when cells are incubated in the continuous presence of antibody or when B73.1 antibody is cross-linked at the cell membrane with an anti-mouse immunoglobulin antiserum. Reaction of lymphocytes with immune complexes also induces modulation of both FcR and B73.1 antigen, without affecting the expression of other antigens on the positive cells. The possibility that the antigen is internalized and digested by the cell after reaction with the antibody is discussed. B73.1 antibody inhibits antibody-dependent cytotoxicity mediated by lymphocytes (K cells) and neutrophils, whereas it does not affect spontaneous cytotoxicity of NK cells. These results suggest the B73.1-defined antigen might be the FcR or a structure closely related to it on K/NK cells.

Human natural killer cells analyzed by B73.1, a monoclonal antibody blocking Fc receptor functions. II. Studies of B73.1 antibody-antigen interaction on the lymphocyte membrane

In this paper, we characterize the antigen recognized by the monoclonal antibody B73.1 and the modification occurring at the membrane of the positive cells after interaction with the antibody. The B73.1-defined antigen is a protein of 50,000 to 72,000 daltons that is sensitive to pronase but not to trypsin treatment. B73.1 antibody, and its F(ab')2 fragment, directly block, at high concentrations, the binding of IgG antibody-sensitized erythrocytes to the Fc receptors (FcR) of a subpopulation of lymphocytes and neutrophils. B73.1 antibody dissociates rapidly from the positive cells, but concomitant modulation of both B73.1 antigen and FcR is induced when cells are incubated in the continuous presence of antibody or when B73.1 antibody is cross-linked at the cell membrane with an anti-mouse immunoglobulin antiserum. Reaction of lymphocytes with immune complexes also induces modulation of both FcR and B73.1 antigen, without affecting the expression of other antigens on the positive cells. The possibility that the antigen is internalized and digested by the cell after reaction with the antibody is discussed. B73.1 antibody inhibits antibody-dependent cytotoxicity mediated by lymphocytes (K cells) and neutrophils, whereas it does not affect spontaneous cytotoxicity of NK cells. These results suggest the B73.1-defined antigen might be the FcR or a structure closely related to it on K/NK cells.

Respirable dust from lignite coal in the Victorian power industry

The results from a 12-month program of static sampling for respirable dust in various work sites of the Victorian power industry are presented. Lignite coal is the major source of dust in this industry. The data appear to be nearly lognormal in distribution and are similar in magnitude to levels reported from North American surface mines and surface work sites. Average 8-hour, time-weighted-average dust concentrations of 0.3 mg/m3 (SD = 0.3) were found in open areas. In enclosed coal handling areas, average concentrations of 0.7 mg/m3 (SD = 0.6) were found.

Lung-function reference values from Victorian power-industry workmen

Reference values for a number of lung function tests performed on a group of apparently healthy Victorian power industry workmen are described. Most workers in this industry have had at least incidental exposure to a range of respiratory hazards, including asbestos dust, at some time in their working lives, but men who recalled handling asbestos materials were excluded from the study. Comparison with other published Australian data shows considerable variation. Differences such as measurement technique, equipment calibration, occupational factors, and selection bias must be considered when reference values from published reports are used for clinical or epidemiological purposes.