Biomedical subjects
P A Baghurst
Publications and source records attributed to P A Baghurst.
Depression among Australian adolescents.
OBJECTIVES: To examine the prevalence and factors associated with depression in Australian adolescents. DESIGN: A representative, multistage probability sample of Australian households conducted in 1998 (part of the National Survey of Mental Health and Well-being). Adolescents completed self-report questionnaires and parents were interviewed using a lay-administered, structured psychiatric interview and several questionnaires. PARTICIPANTS: 1,490 adolescents aged 13-17 years and their parent or main caregiver. MAIN OUTCOME MEASURES: Prevalence of depression in adolescents, as reported by parents and by adolescents themselves; demographic factors; health-risk behaviours; and rate of use of support services. RESULTS: Of the 1,490 adolescents originally sampled, 150 (10%) did not complete responses to questions on depression and were excluded from the analysis. Seventy of the remaining 1340 adolescents (5.2%; 95% CI, 4.0%-6.4%) met criteria for self-reported depression. Agreement between parent- and adolescent-reported depression was poor (kappa=0.27). Adolescent-reported depression was associated with increased suicide plans (odds ratio [OR], 2.83; 95% CI, 1.19-6.70) and attempts (OR, 9.05; 95% CI, 3.49-23.50) in the previous year, use of marijuana 10 or more times in the previous month (OR, 2.88; 95% CI, 1.25-6.64), having conduct disorder (OR, 4.09; 95% CI, 1.23-13.63) and use of school support services (OR, 4.71; 95% CI, 1.82-12.22). Those who used any kind of support service (24/70; 34%) used a mean of 2.9 services (mode, 2; range, 1-5). Three per cent (2/70) of depressed adolescents had been treated with antidepressants. CONCLUSIONS: Depressed adolescents exhibit higher rates of health-risk behaviours and psychosocial impairment than non-depressed adolescents, but only a small number receive appropriate treatment. Staff working in school-based services should be trained to identify adolescents with depression and facilitate referral for treatment.
Efficacy of once-daily tobramycin monotherapy for acute pulmonary exacerbations of cystic fibrosis: a preliminary study.
Our objective was to compare the efficacy, safety, and microbiology of once-daily intravenous (IV) tobramycin with conventional 8-hourly tobramycin/ceftazidime IV therapy for acute Pseudomonas aeruginosa (PA) pulmonary exacerbations in cystic fibrosis (CF). CF patients with PA-induced pulmonary exacerbations were allocated to receive either once-daily tobramycin (Mono) or conventional therapy with tobramycin/ceftazidime given 8-hourly (Conv). The two longitudinal groups received therapy in a double-blind, randomized manner over a period of 2 years. Tobramycin doses were adjusted to achieve a daily area under the time-concentration curve of 100 mg x hr/L in both groups. Results were assessed for both short-term changes (efficacy and safety after 10 days of IV antibiotics during acute exacerbations) and long-term changes (efficacy, safety, and sputum microbiology between study entry and exit). Pulmonary function tests (PFTs) on admission were similar in both groups. After 10 days of IV antibiotics, absolute mean improvements in percent of predicted PFTs were 12.8, 12.1, and 13.7 for forced expiratory volume in 1 sec (FEV(1)), forced vital capacity (FVC), and forced expired flow between 25--75% of FVC (FEF(25--75%)) in the Conv group (n = 51 admissions) compared to 10.6, 9.9, and 10.6 in the Mono group (n = 47)(P<0.05 for all). Sixteen percent in the Conv group and 15% of patients in the Mono group did not respond to therapy by day 10. Long-term PFT patterns were similar for the Conv and Mono groups. The time between admissions did not differ. The Mono group showed a significant increase in tobramycin minimum inhibitory concentrations (MICs) against PA from study entry to study exit (P = 0.02, n = 27 strains); this failed to reach significance in the Conv group (P = 0.08, n = 25). There was no significant increase in the number of isolates, with MIC> or =8 mg/L in both groups. No short- or long-term changes in audiology or serum creatinine were found in either group. After 10 days of IV therapy, the urinary enzyme N-acetyl-beta-d-glucosaminidase/creatinine ratios increased in both groups (P0.05). This increase was greater in the Conv compared to the Mono group (P < 0.05). We conclude that this pilot study indicates once-daily tobramycin therapy to be as effective and safe as conventional 8-hourly tobramycin/ceftazidime therapy. Combination antibacterial therapy appears to offer no clinical advantage over once-daily tobramycin monotherapy. Tobramycin once-daily monotherapy is a potential alternative to conventional IV antibacterial therapy which deserves further investigation, including the impact on susceptibility of PA to tobramycin.
The mental health of young people in Australia: key findings from the child and adolescent component of the national survey of mental health and well-being.
OBJECTIVE: To identify the prevalence of three mental disorders (Depressive Disorder, Conduct Disorder and Attention-Deficit/Hyperactivity Disorder), the prevalence of mental health problems, the health-related quality of life of those with problems, and patterns of service utilisation of those with and without mental health problems, among 4-17-year-olds in Australia. To identify rates of health-risk behaviours among adolescents with mental health problems. METHOD: The mental disorders were assessed using the parent-version of the Diagnostic Interview Schedule for Children Version IV. Parents completed the Child Behaviour Checklist to identify mental health problems and standard questionnaires to assess health-related quality of life and service use. The Youth Risk Behaviour Questionnaire completed by adolescents was employed to identify health-risk behaviours. RESULTS: Fourteen percent of children and adolescents were identified as having mental health problems. Many of those with mental health problems had problems in other areas of their lives and were at increased risk for suicidal behaviour. Only 25% of those with mental health problems had attended a professional service during the six months prior to the survey. CONCLUSION: Child and adolescent mental health problems are an important public health problem in Australia. The appropriate balance between funding provided for clinical interventions focusing on individual children and families and funding for interventions that focus on populations, requires careful study. The latter are an essential component of any strategy to reduce mental health problems as the high prevalence of problems makes it unlikely that individual care will ever be available for all those needing help. Clinical and population health interventions must take into account the comorbid problems experienced by children with mental disorders.
Lifetime low-level exposure to environmental lead and children's emotional and behavioral development at ages 11-13 years. The Port Pirie Cohort Study.
The Port Pirie Cohort Study is the first study to monitor prospectively the association between lifetime blood lead exposure and the prevalence of emotional and behavioral problems experienced by children. Lead exposure data along with ratings on the Child Behavior Checklist were obtained for 322 11-13-year-old children from the lead smelting community of Port Pirie, Australia. Mean total behavior problem score (95% confidence interval (CI)) for boys whose lifetime average blood lead concentration was above 15 microg/dl was 28.7 (24.6-32.8) compared with 21.1 (17.5-24.8) in boys with lower exposure levels. The corresponding mean scores (95% CI) for girls were 29.7 (25.3-34.2) and 18.0 (14.7-21.3). After controlling for a number of confounding variables, including the quality of the child's HOME environment (assessed by Home Observation for Measurement of the Environment), maternal psychopathology, and the child's IQ, regression modeling predicted that for a hypothetical increase in lifetime blood lead exposure from 10 to 30 microg/dl, the externalizing behavior problem score would increase by 3.5 in boys (95% CI 1.6-5.4), and by 1.8 (95% CI -0.1 to 11.1) in girls. Internalizing behavior problem scores were predicted to rise by 2.1 (95% CI 0.0-4.2) in girls but by only 0.8 (95% CI -0.9 to 2.4) in boys.
Sociodemographic and behavioural determinants of blood lead concentrations in children aged 11-13 years. The Port Pirie Cohort Study.
OBJECTIVE: To describe the determinants of blood lead concentration in children with long term environmental exposure to lead. DESIGN: Prospective cohort study. SETTING: The lead smelting town of Port Pirie, South Australia, and surrounding townships. PARTICIPANTS: 326 children born in and around Port Pirie, 1979-1982, followed up until age 11-13 years in 1993-1994. MAIN OUTCOME MEASURES: Blood lead concentrations assessed at birth and at multiple ages up to 11-13 years; average lifetime blood lead concentration. RESULTS: Mean blood lead concentration rose sharply over the ages 6 to 15 months, reached a maximum around 2 years of age, and declined steadily as the children grew older. There was no difference in blood lead concentration between boys and girls until they reached the age of 11-13 years, when mean blood lead concentration in boys (8.4 micrograms/dL [0.41 mumol/L]) was slightly higher than in girls (7.5 micrograms/dL [0.36 mumol/L]). Residential area and father's employment site were the two variables most strongly predictive of a child's blood lead concentration at the end of primary school. Poorer-quality home environment was also found to be an independent contributor to blood lead concentrations. CONCLUSIONS: Age-related factors, and possibly recent concerted efforts to decrease entry or re-entrainment of lead into the environment at Port Pirie, have resulted in most children in our study having blood lead concentrations below 10 micrograms/dL (0.48 mumol/L) at the end of their primary school years. Lead exposure during a child's early years remains an important contributor to average lifetime exposure.
Polycyclic aromatic hydrocarbons and heterocyclic amines in the diet: the role of red meat.
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Otoacoustic emissions in 28 young adults exposed to amplified music.
Popular concern about widespread damage to the hearing from exposure to amplified music continues, although there has been little firm evidence of permanent effects in casual listeners. Measurement of transient evoked otoacoustic emissions (TEOAEs) provides a sensitive technique for testing outer hair cell (OHC) function, and was used in this study of 28 young adults aged 18-25 years, whose only significant source of noise exposure was loud music, to look for evidence of poorer cochlear function in those of greater exposure; they provided 27 right ears and 27 left ears suitable for measurement of TEOAE strength. Estimates of subjects' total noise dose were obtained from self-reports of the duration and intensity of their exposure to music and other sources of noise. Ears with greater exposure to loud music showed significantly weaker TEOAEs than less exposed ears in response to a 4 kHz tone burst, or in response to a saturating (82 dBSPL) click if the response was treated with a high-frequency bandpass filter (2-4 kHz) (p<0.05). Differences between more exposed and less exposed groups of ears were most marked in the 2 kHz half-octave band for right ears, and in the 2.8 kHz half-octave band for left ears. A hypothesis is proposed that weakness in TEOAEs as a result of exposure to loud music is seen first in the 2 kHz region of the emission spectrum, and later at higher frequencies; and that for a given amount of exposure, TEOAE weakness (or OHC damage) is more advanced in left ears than in right.
Declining blood lead levels and changes in cognitive function during childhood: the Port Pirie Cohort Study.
CONTEXT: Many studies have found a significant inverse association between early exposure to environmental lead and cognitive function in childhood. Whether these effects are reversible when exposure is reduced is not clear. OBJECTIVE: To assess the reversibility of the apparent effects of lead on cognitive abilities in early childhood by testing whether declines in blood lead concentrations beyond the age of 2 years are associated with improvements in cognition. SETTING: Urban and rural communities surrounding a large lead smelter in Port Pirie, South Australia. PARTICIPANTS: A total of 375 children followed up from birth to the age of 11 to 13 years. DESIGN: Long-term prospective cohort study. MAIN OUTCOME MEASURES: The Bayley Mental Development Index at age 2 years, the McCarthy General Cognitive Index at age 4 years, and IQs from the Wechsler Intelligence Scale (revised version) at ages 7 and 11 to 13 years. RESULTS: Mean blood lead concentrations in the children decreased from 1.02 pmol/L (21 .2 microg/dL) at age 2 years to 0.38 micromol/L (7.9 microg/dL) at age 1 1 to 13 years, but cognitive scores in children whose blood lead concentration declined most were generally not improved relative to the scores of children whose blood lead levels declined least. Changes in IQ and declines in blood lead levels that occurred between the ages of 7 and 11 to 13 years (r= 0.12, P= .09) suggested slightly better cognition among children whose blood lead levels declined most. CONCLUSION: The cognitive deficits associated with exposure to environmental lead in early childhood appear to be only partially reversed by a subsequent decline in blood lead level.
Does breastfeeding at six months predict cognitive development?
There is controversy over whether the method of feeding in infancy affects intellectual development. We investigated the relationship between breastfeeding status at 6 months of age and long-term cognitive development in a cohort of 375 children born in Port Pirie, South Australia, between 1979 and 1982. Cognitive assessments were conducted at ages 2, 4, 7 and 11 to 13 years. After adjustment for sociodemographic, environmental and biomedical factors, a small, statistically non-significant, beneficial effect of breastfeeding on cognitive functioning was observed. Compared with the bottle-fed children, the breast-fed children had a 3.4 (95% CI -0.1 to 6.9), 1.3 (-2.3 to 4.9), 1.2 (-2.0 to 4.4) and 0.8 (-1.9 to 3.5) point advantage on the Bayley Mental Developmental Index at age 2 years, the McCarthy General Cognitive Index at age 4 years and the Wechsler Full-Scale IQ at ages 7 and 11 to 13 years, respectively. Our data suggest that any beneficial effect of breastfeeding on cognitive development is quite small in magnitude.
Dietary fiber and risk of benign proliferative epithelial disorders of the breast.
Following a recent finding, from a case-control study in Adelaide, South Australia, of a reduced risk of breast cancer among women consuming diets rich in fiber, the fiber densities in the diets of 354 women with incident benign proliferative epithelial disorders of the breast (BPED) were compared with the fiber densities of the diets of 354 matched community controls and with those of 189 unmatched controls having breast conditions for which there was no evidence of BPED at biopsy. Fiber intakes were estimated by means of a self-administered quantitative food-frequency questionnaire, and the risk of BPED was estimated for each quintile of fiber density (grams of fiber/megaJoule of total energy intake) relative to an arbitrarily assigned risk of one for the lowest quintile. For women with the highest dietary fiber densities the estimated risk was 0.64 (95% CI 0.34, 1.19) when cases were compared with community controls, and 0.45 (95% CI 0.24, 0.82) when cases were compared with biopsy-negative controls. Similar trends in risk were observed for the intakes of other major fiber components, the association being stronger when the comparison was made with biopsy-negative as opposed to community controls. If these findings can be substantiated, they may open the way to dietary intervention strategies for reducing the incidence of breast cancer.
Exposure to environmental lead and visual-motor integration at age 7 years: the Port Pirie Cohort Study.
Early childhood exposure to environmental lead may result in subtle deficits in neuropsychological development. Most studies, however, have reported global measures of development, and the findings have not been consistent. In this report, we examine the association between blood lead concentration and a specific aspect of neuropsychological development, visual-motor integration. Each child in a cohort of 494 children living in and around the lead smelting town of Port Pirie, South Australia, was followed for its first 7 years of life. Serial blood samples were collected at various ages to estimate the lifetime burden of each individual. At the time of each blood sampling, systematic information was obtained on a wide range of other variables relevant to child development. We evaluated visual-motor integration at age 7 with the Beery Developmental Test of Visual-Motor Integration (mean score: 13.4). There was an inverse relation between blood lead concentration and visual-motor performance. After adjustment for potential confounding factors, both prenatal and postnatal blood lead concentrations exhibited a dose-related inverse association with children's visual-motor performance. For an increase in life-time average blood lead concentration from 10 micrograms per dl (0.48 mumol per liter) to 30 micrograms per dl (1.45 mumol per liter), the estimated deficit in children's visual-motor performance was 1.6 points (95% confidence interval = 0.3-2.9). The results indicate that visual-motor integration may be a more sensitive index than global measures of development, such as intelligence quotient, for the assessment of lead effects on child development.
Tooth lead levels and IQ in school-age children: the Port Pirie Cohort Study.
The relation between lead concentration in deciduous central upper incisor teeth and intellectual functioning was examined in 262 children who were followed from birth to age 7 years in the lead smelter town of Port Pirie, South Australia, and its environs. Intellectual functioning of the children was assessed over the 3-year period from 1986 to 1989 with the revised Wechsler Intelligence Scale for Children (WISC-R) while each child was in his or her eighth year. There was an inverse relation between tooth lead concentration and intellectual development; the intelligence quotient declined by 2.6 points (90% confidence interval (CI) 0.13-4.9) for each natural-log unit increase in tooth lead concentration, expressed in parts per million. Some WISC-R subscales were more strongly associated with lead exposure than others. In particular, tooth lead was significantly negatively associated with scores for the "Block Design" test (partial regression coefficient -1.25 points per unit of natural-log tooth lead; 90% CI -0.61 to -1.89). No statistically significant interaction between a child's sex and tooth lead concentration was found for any of the WISC-R scales. These findings are in agreement with previously published results from this cohort for which serial blood lead concentrations were used to estimate lifetime lead burden.
High-fiber diets and reduced risk of breast cancer.
In a case-control study of 451 women with breast cancer and 451 population-based controls from metropolitan Adelaide, Australia, the risk of breast cancer was studied in relation to intake of dietary fiber and various fiber components. Intakes were estimated by means of a self-administered quantitative food-frequency questionnaire, and risks of breast cancer were estimated for each quintile of fiber density (intake/megaJoule of total energy intake) relative to an arbitrarily assigned risk of unity for women in the lowest quintile of fiber density. There were highly significant reductions in relative risk associated with increasing intake of a number of components of total dietary fiber. In women with the highest 20% estimated dietary densities of total non-starch polysaccharides (NSP), the relative risk of breast cancer was 0.46, and a test for trend across the quintiles was significant at p < 0.001. Separate risk estimations for various fiber components defined by the Englyst method of analysis revealed highest risk reductions associated with high densities of mannose from insoluble NSP and of glucose from soluble NSP. For many fiber components the point estimates of relative risk were quite similar both for pre- and for post-menopausal women, although results for the latter (who comprised over two thirds of all cases) were statistically more significant. The study provides strong support for recent conjecture that foods rich in dietary fiber may be protective against breast cancer.
Demographic and dietary profiles of high and low fat consumers in Australia.
STUDY OBJECTIVE: To determine the socio-demographic, attitudinal, and dietary correlates of high and low fat consumption in the community. DESIGN: The study was undertaken using a postal survey format. A questionnaire was sent for self completion to a randomised sample of the adult population of two Australian states. PARTICIPANTS: Adult participants were selected randomly from the Electoral Rolls of the states of Victoria and South Australia. As voting at elections is compulsory in Australia, these rolls contain the names of all Australian citizens over the age of 18 years. Altogether 3209 respondents completed the survey giving a response rate of 67%. MAIN RESULTS: Lower than average fat consumption was more common in women. Age was a significant factor only in men. Occupation was not related to lower than average fat consumption but manual work and low occupational prestige were linked to higher than average consumption in men. People with a history of conditions related to heart disease were more likely to be low consumers but medical history did not distinguish high from average consumers. Low fat consumption was linked to higher refined and natural sugar consumption and higher alcohol consumption, but protein and complex carbohydrate consumption did not vary with fat consumption. Low fat diets also had higher densities of fibre and most vitamins and minerals, the exceptions being retinol, zinc, and vitamin B12, nutrients generally linked to meat and dairy consumption. Of the latter, only the low zinc concentrations, which are already borderline in the community, pose a potential nutritional problem. CONCLUSIONS: This study showed very strong links between dietary fat intake and the intake of nearly all other nutrients in the diet. The results highlight the need to consider relationships between nutrients not only for purposes of nutrition education but also in relation to nutritional epidemiology studies.
Antioxidant vitamins and low-density-lipoprotein oxidation.
Low-density-lipoprotein (LDL) oxidation was examined in 22 subjects (10 men, 12 women) after a daily dose of 18 mg beta-carotene, 900 mg vitamin C, and 200 mg alpha-tocopherol for 6 mo. Control subjects (12 men, 11 women) took no vitamin supplements. After 3-mo supplementation plasma concentrations of beta-carotene, alpha-tocopherol, and ascorbic acid increased fivefold (P < 0.001), 55% (P < 0.01), and 27% (P < 0.05), respectively. There was no difference from baseline in rate of oxidation or total amount of conjugated diene produced between subjects taking or not taking vitamins. Malondialdehyde in LDL before and after oxidation was not different between the two groups. Lag time before the onset of oxidation was significantly lengthened after antioxidant supplementation (28% and 35% after 3 and 6 mo, respectively, P < 0.001). There was a significant independent correlation between percent change in lag time and percent change in plasma alpha-tocopherol (r = 0.47, P < 0.01).
Childhood emotional and behavioural problems: a comparison of children's reports with reports from parents and teachers.
Paediatricians are often asked to assess children with emotional and behavioural problems and are faced with the dilemma that reports about the children's behaviour obtained from the children, and from their parents and teachers, may differ. This study compares the number of childhood emotional and behavioural problems reported by children living in the community, with the number of problems reported by their parents and teachers. When describing both internalizing and externalizing problems, the children consistently reported that they had more problems than were reported by either their parents or teachers. This pattern was particularly evident with reports from older female children who reported many more internalizing problems than were reported by their parents and teachers. Possible reasons for the differences between reports from children and the other informants are discussed.
Emotional and behavioural problems experienced by children living in single-parent families: a pilot study.
This study compared the prevalence of emotional and behavioural problems experienced by 10-11 year old and 14-15 year old children living in single-parent and two-parent families in South Australia. The 10-11 year old male children living in single-parent families were found to have significantly more emotional and behavioural problems than 10-11 year old male children living in two-parent families. In particular, the younger male children living in single-parent families experienced more externalizing behaviour problems than younger male children living in two-parent families. It is suggested that paediatricians and general practitioners need to be aware of children who are at particular risk for developing emotional and behavioural problems, and the approaches which may be employed to provide help.