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Biomedical subjects

W Hall

Publications and source records attributed to W Hall.

At least 217 records · Page 12Linked to original sources
PubMed1986

The Agent Orange controversy after the Evatt Royal Commission.

The Evatt Royal Commission Report on the Use and Effects of Chemical Agents on Australian Personnel in Vietnam has authoritatively rejected the substantive claims that were made by the Vietnam Veterans' Association of Australia about the adverse effects of exposure to phenoxy herbicides in Vietnam on the health of Vietnam veterans and their families. The Commission concluded that Vietnam veterans were not exposed to toxic levels of chemicals in Vietnam; that they are not at any increased risk of fathering children with birth defects, or contracting cancer; and that, although they have slightly higher rates of psychiatric disorder, heart disease, alcoholism and alcohol-related disease, these effects are unconnected with exposure to chemicals in Vietnam. The reasons for these findings deserve to be given the widest possible publicity. Only by doing so is there any prospect of dissolving the misapprehension that Vietnam veterans have been poisoned by herbicides.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1986

Social class and survival on the S.S. Titanic.

Passengers' chances of surviving the sinking of the S.S. Titanic were related to their sex and their social class: females were more likely to survive than males, and the chances of survival declined with social class as measured by the class in which the passenger travelled. The probable reasons for these differences in rates of survival are discussed as are the reasons accepted by the Mersey Committee of Inquiry into the sinking.

England↗
PubMed1986

Simultaneous multiple comparison procedures in psychiatric research.

The multiple comparison problem arises in any research design in which the scores of more than two groups are compared on a single dependent variable. The analysis of variance provides a way of testing the null hypothesis that all population means are equal with a type 1 error rate of alpha. When the joint null hypothesis is accepted, the outcome of such a test is unambiguous: all population means are equal. When the null hypothesis is rejected, ANOVA is insufficient to identify the pattern of departure from equality. The Scheffe procedure can be used to test any number and type of contrast that is suggested by an inspection of the data. It ensures that the chance of incorrectly rejecting one or more hypotheses in the set so tested cannot exceed alpha. Contrasts between the population means which are specified independently of the data can be tested using Bonferroni-adjusted t tests to control the experimentwise error rate. Factorial ANOVA designs can also be analysed by testing linear contrasts. If a researcher has definite expectations about the pattern of mean differences, he can test a set of planned contrasts with a familywise error rate (if contrasts are written within main effects and interaction effects) or an EER. If he is uncertain about which hypotheses to test, post hoc procedures which are modifications of the Scheffe technique can be used.

Analysis of Variance↗
PubMed1986

Simultaneous multiple comparison procedures for categorical data.

Methods are outlined for performing simultaneous multiple comparisons between groups when the dependent variable is one in which subjects are assigned to one of two or more categories. These methods provide tests which are analogous to Scheffe- and Bonferroni-adjusted tests of contrasts in the analysis of variance. Examples are provided of each of these procedures.

Analysis of Variance↗
PubMed1986

Does depressive illness in the elderly have a poor prognosis?

The few available longitudinal studies of depressive illness in the elderly indicate a poor prognosis. Various risk factors are discussed. Both severe and chronic physical illness, and severity of the depressive disorder are the two most important prognostic factors. The possibility of interactional effects between these risk factors should be studied. Most studies to date have been of severely depressed patients and this may give an unduly pessimistic picture. A case is made for the desirability of well-designed prognostic longitudinal studies with subjects being drawn from a wide spectrum of severity of illness.

Adjustment Disorders↗
PubMed1986

Statistical power in psychiatric research.

Statistical power is neglected in much psychiatric research, with the consequence that many studies do not provide a reasonable chance of detecting differences between groups if they exist in the population. This paper attempts to improve current practice by providing an introduction to the essential quantities required for performing a power analysis (sample size, effect size, type 1 and type 2 error rates). We provide simplified tables for estimating the sample size required to detect a specified size of effect with a type 1 error rate of alpha and a type 2 error rate of beta, and for estimating the power provided by a given sample size for detecting a specified size of effect with a type 1 error rate of alpha. We show how to modify these tables to perform power analyses for multiple comparisons in univariate and some multivariate designs. Power analyses for each of these types of design are illustrated by examples.

Clinical Trials as Topic↗
PubMed1985

Methionine enkephalin as a possible neuromodulator of regional cerebral blood flow.

In swine, cerebral blood flow was documented by a left ventricular injection of radiolabeled 15-micron spheres. Utilizing this procedure, the effect of the putative neurotransmitter methionine-enkephalin on regional cerebral blood flow was systemically evaluated. Our results revealed that a peripheral infusion of methionine enkephalin into miniature swine significantly increased cerebral blood flow in the basal ganglia, cerebellum, pons, inferior parietal cortex and frontal cortex. Non-significant increases were observed in the hippocampus, occipital cortex and medulla oblongata while no effect on blood flow was observed in the pituitary gland. Significance of these results in the potential role of methionine enkephalin as a modulator of blood flow to the brain.

Animals↗
PubMed1985

The economic costs of schizophrenia. Implications for public policy.

The direct and indirect costs associated with schizophrenia in Australia were calculated using the incidence approach and compared with similar costings of myocardial infarction in Australia and the United States. In Australia schizophrenia affects one-twelfth as many people as does myocardial infarction, yet costs half as much. This is because the stream of costs associated with each case of schizophrenia is six times the stream of costs associated with myocardial infarction. To illustrate the utility of this costing approach, the information was used to estimate the cost-benefit ratio likely to follow the introduction of social intervention strategies. The information also showed that Australian support for research in schizophrenia is inadequate when compared with that for myocardial infarction and quite out of proportion to the cost of schizophrenia to the community.

Adolescent↗
PubMed1985

Early sensory-perceptual changes in Huntington's disease.

Forty-four patients at risk for Huntington's disease and seventeen diagnosed as having the disease were studied longitudinally over a nine-year period to assess the evolution of cognitive impairment. Results showed that there were measurable changes in sensory-perceptual functions well in advance of the emergence of the movement disorder. Discrimination between patients with Huntington's disease and those at risk for the disease based on tests of sensory-perceptual functioning resulted in a correct classification rate of 95.1%. Subjects who had changed from being at risk to having the disease nearly all had discriminant scores from their first test sequence lying in either the disease range or the pre-symptomatic disease range. The present organic model of Huntington's disease is discussed in light of these findings and implications of the mathematical model underlying prediction are discussed.

Adolescent↗
PubMed1985

Estimating the economic costs of schizophrenia.

The economic costs of schizophrenia in New South Wales, Australia, were estimated using an incidence-based approach. The incidence of the disease was obtained from a case register. Direct treatment costs were calculated from length of stay data, the probability of readmission, and a direct costing of inpatient and outpatient care. Indirect costs were calculated from tables of average weekly earnings and work-force participation rates modified for the expected types of outcome. The prodrome was costed similarly. Costs were $139 million (in 1975 U.S. dollars), or $29 per head of the population of the State. A sensitivity analysis indicated that the likely margin of error of the estimate was plus or minus 15 percent. Comparison with the costs of myocardial infarction (in the same State at the same time and costed by the same methods) demonstrated that schizophrenia is a costly disease.

Adolescent↗
PubMed1985

Do Vietnam veterans suffer from toxic neurasthenia?

This paper evaluates the claim that Vietnam veterans with psychiatric disorders are suffering from toxic neurasthenia--a neurasthenic syndrome caused by exposure to pesticides while serving in Vietnam.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1985

The problem of multiple inference in psychiatric research.

This paper deals with the problem of multiple inference in psychiatric research, an issue which arises whenever a researcher has to make more than one statistical inference in a single research study. It frequently arises in psychiatric research because of multivariate study designs, with subjects being measured on more than one dependent variable with the intention of studying differences between groups in mean scores. The disadvantages of the commonly adopted strategy of using multiple univariate tests (e.g. multiple t-tests) are outlined. Two broad strategies--Bonferroni-adjusted univariate tests and multivariate statistical analysis--are introduced. Their advantages and disadvantages are discussed in terms of their usefulness in confirmatory and exploratory research in psychiatry.

Analysis of Variance↗
PubMed1984

Psychotropic drug prescribing in an Australian general practice.

Information about psychotropic drug prescribing in one general practice was compared with overall information about such prescribing in Australia. Over the period 1978-81 there was a significant reduction in the number of prescriptions issued for psychotropic drugs. Prescriptions for hypnotics, sedatives and minor tranquilizers were more common than those for antidepressants or major tranquilizers. The indications for prescribing were distributed equally among three groups of conditions: psychological disorders, sleep problems and physical diseases. Patients for whom psychotropic drugs were prescribed had a greater overall morbidity and used medical care services more than other patients. Only 9% of patients in 1981 were issued with a prescription for one of the four most commonly prescribed psychotropic drugs. A relatively small proportion of patients, most of them elderly women, received the largest proportion of the prescriptions.

Adolescent↗
PubMed1984

Obesity, alcohol consumption and blood pressure in Australian men and women. The National Heart Foundation of Australia Risk Factor Prevalence Study.

The associations of obesity and alcohol consumption with blood pressure and the prevalence of hypertension were studied in 5550 male and female subjects aged 25 to 64 years, surveyed in the National Heart Foundation of Australia 1980 Risk Factor Prevalence Study. Body mass index was significantly and independently associated with blood pressure levels in both sexes. A maximum of 30% of hypertension in the study population could be attributed to overweight. The association between body mass index and hypertension was greater in men under 45 years in whom a maximum of 60% of hypertension could be attributed to overweight. In both men and women receiving antihypertensive treatment, body mass index was positively associated with blood pressure. Overweight hypertensives were less likely to achieve normal blood pressure on treatment. Alcohol consumption was significantly and independently associated with blood pressure levels in males. A similar trend in females failed to reach statistical significance because of the lesser consumption of alcohol by females. A maximum of 11% of hypertension in males and 1% in females could be attributed to alcohol consumption. These estimates were reduced when age and body mass were taken into account.

Adult↗
PubMed1984

The incidence of schizophrenia in New South Wales, Australia. A psychiatric register study.

Age-specific estimates of the incidence of schizophrenia in NSW, Australia, have been made using two methods, one based on a psychiatric register and the other based on routinely collected hospital morbidity data. Similar results were obtained by both methods. The estimates lie towards the bottom of the range of incidence estimates of schizophrenia that have been published for some other countries, and are lower than estimates from a number of U.S. studies. The diagnostic criteria of schizophrenia employed by Australian psychiatrists conform closely to DSM-III criteria.

Adolescent↗