Biomedical subjects
R Jackson
Publications and source records attributed to R Jackson.
Validation of coronary heart disease death certificate diagnoses.
Data from a coronary heart disease register in Auckland have been used to validate routine death certificate data produced by the National Health Statistics Centre. The register used current World Health Organisation criteria for definite or possible coronary heart disease and identified all suspected events in people aged less than 65 years for the years 1983 and 1984. During this period 768 coronary heart disease cases were included in the register and in the same population 772 death certificates were coded 410-414 (coronary heart disease), according to the ninth revision of the International Classification of Diseases, by the National Health Statistics Centre. Ninety one percent of deaths meeting the register's criteria for definite or possible coronary heart disease were coded 410-414 in the official data. Conversely of all death certificates coded 410-414, 93% were registered as due to coronary heart disease. The validity of subcategories was considerably lower; only 49% of deaths coded 410 (acute myocardial infarction) were categorised as definite myocardial infarction by the register. These findings suggest that the broad official statistics for the category coronary heart disease mortality (codes 410-414) are accurate to within approximately 10% in New Zealand; the validity of the subcategory myocardial infarction (code 410) is considerably lower.
Statistical testing and estimation in medical research.
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Rethinking the treatment of mild hypertension.
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What should be done about hypercholesterolaemia?
Recent developments have given new impetus to the prevention of coronary heart disease through the control of hypercholesterolaemia and there is increasing pressure to identify and treat individuals with high serum cholesterol levels. It is now imperative that we develop a rational and cost-effective management policy. Epidemiological considerations indicate that although various strategies exist, the most cost-effective method of reducing the burden of hypercholesterolaemia in New Zealand would be by changing the nations diet as a whole. We cannot afford a strategy based primarily on treating high risk individuals.
Reducing hyperlipidaemia.
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Prevention and control of hypertension in New Zealand: a reappraisal.
A new national policy for the prevention and control of hypertension is required in New Zealand. The first priority is the prevention of hypertension with the development of a population strategy directed at encouraging healthy nutritional and exercise habits. Pharmacological management or specific nonpharmacological treatment of individuals is the second priority and decisions about treatment levels have important logistic and cost implications. Given the limited absolute benefits of treatment to individuals, the current policy of initiating treatment at a diastolic blood pressure of greater than or equal to 95 mmHg should be revised upwards. A population approach to the prevention of hypertension is essential in New Zealand because the majority (57%) of excess deaths due to raised blood pressure occur in people with diastolic blood pressure in the range 80-94 mmHg. A fall in the population mean diastolic blood pressure of 2 mmHg would have the same effect on total mortality rates as the successful treatment of everyone with a diastolic blood pressure greater than or equal to 100 mmHg. A national multidisciplinary group should be established to formulate strategies for preventing hypertension in New Zealand and to review current treatment guidelines.
Diet, serum cholesterol and the prevention of coronary heart disease in New Zealand.
A combination of the population strategy and the high risk strategy has been recommended for the prevention and control of coronary heart disease in New Zealand. In this paper, using data from a variety of sources, we estimate the potential relative benefits of these two strategies to reduce the contribution of diet and high blood cholesterol to coronary heart disease mortality in New Zealand. It is estimated that diet is responsible, at a minimum for between 22% (1600 deaths) and 39% (2800 deaths) of the coronary heart disease mortality in New Zealand each year. Achievement of the suggested short term dietary goals for the New Zealand population would have at least the same benefit as the identification and successful treatment of all people in the top 10% of the serum cholesterol distribution. This indicates that the population strategy should have higher priority in efforts to prevent and control coronary heart disease. Decisions concerning the level at which elevated blood cholesterol levels are treated pharmacologically will have important logistic and cost implications; national guidelines are required for the management of people with high blood cholesterol levels.
Is the pharmacological treatment of mild to moderate hypertension cost effective in stroke prevention?
Pooled data from clinical trials show that the incidence of fatal and nonfatal strokes combined is reduced by approximately 39% (95% CI: -48% to -28%) with antihypertensive treatment. However, given the relatively low incidence of stroke, it can be calculated that about 530 to 1375 mild to moderate hypertensive patients would need to be treated per year to prevent one stroke. Applying these results to the health service costs, both public and private, of treating mild to moderate hypertension in New Zealand we have estimated that the cost of preventing one stroke in those aged 35-64 years at between $110,900 and $285,400 in 1982 dollars. The offsetting hospital and community care costs to the health services of treating a stroke, was approximately $6500 giving a net cost of between $104,000 and $279,000 per stroke prevented. The cost of preventing a death from stroke was estimated to be between $356,000 and $1,822,000. Per year of life saved, this appears to be well in excess of such costly interventions as coronary artery bypass, heart transplantation and renal dialysis. Greater use should be made of inexpensive diuretics and nonpharmacological methods for the management of hypertension. A population strategy, rather than the present expensive high risk approach, could be far more cost effective in stroke prevention.
Serum cholesterol and coronary heart disease: Auckland general practitioners' attitudes and practices in 1986.
The relationship between elevated serum cholesterol and coronary heart disease, is now generally accepted as being causal. To examine current attitudes and practices regarding the treatment of high serum cholesterol, questionnaires were sent to a randomly selected sample of general practitioners in the Takapuna health district during 1986. The response rate among the 92 doctors in general practice at the time of the study was 80%. The majority of general practitioners (82.5%) believed that there was a casual relationship between high serum cholesterol and coronary heart disease and that reducing levels would help prevent coronary heart disease. Almost all general practitioners (96%) were screening some groups of patients for high serum cholesterol, with most screening those with symptomatic coronary heart disease or associated risk factors, and 15% screening all patients. Although almost 90% of general practitioners had patients on diet therapy and one third had patients on drug treatment, there was wide variation in attitudes regarding the serum cholesterol levels meriting dietary or drug treatment. This suggests that there is still considerable confusion as to when and how to treat high cholesterol levels and that specific national guidelines for the detection and management of high serum cholesterol are required as part of a comprehensive programme to prevent coronary heart disease.
Decisions near the end of life.
Designing behavior change programs and evaluating their effects on patient care has been a persistent challenge in research on continuing medical education. The challenge becomes even more complex when we aim to change behaviors that are interactive and highly influenced by the formal and informal institutional context. The authors describe an interdisciplinary continuing education program in bioethics that is designed to effect just such behaviors. The program aims to help hospital and long-term care facilities improve their ability to resolve the ethical dilemmas inherent in terminal care decisions. Targeted to interdisciplinary groups of physicians, nurses, social workers, pastoral counselors, and administrators, Decisions Near the End of Life will provide strategies and tools for examining institutional policies and team practices as well as more traditional information, education, and skill building. The authors describe the program's rationale and design, and raise questions about the potential for developing interdisciplinary, action-oriented CME on other topics.
Class II MHC expression in normal adrenal cortex and cortical cells in autoimmune Addison's disease.
It has been proposed that aberrant expression of class II major histocompatibility complex (MHC) molecules by target cells may be an initiating factor in some forms of organ specific autoimmunity. This hypothesis was tested in relation to the autoimmune form of Addison's disease by studying autopsy adrenal glands from eight patients who had died of recent onset idiopathic Addison's disease. Using an immunohistochemical technique, class II MHC expression was found in a minority of adrenal cortical cells in the zona reticularis in 25 normal and four hyperplastic glands, while in Addison's disease almost all residual cortical cells expressed class II MHC. Three tuberculous adrenals showed increased staining of cortical cells around areas of chronic inflammation. It is concluded that since adrenal cortical cells of the normal gland express class II MHC, aberrant expression of this product cannot be invoked as an initiating mechanism in autoimmune adrenalitis. The increased cortical expression of class II MHC seen in idiopathic Addison's disease and tuberculosis may be due to local release of lymphokines by inflammatory cells.
Long-term assessment of patients with macroprolactinemia.
Three patients presenting with hyperprolactinemia associated with normal menses, retained fertility, and minimal lactation were followed for a period of 5 to 7 years. All had associated thyroid autoimmune disorders (one with chronic thyroiditis and two with Graves' disease). Their major form of circulating prolactin (PRL) was in the large-molecular weight (150K) form (macroprolactinemia). Whereas normal serum content of 150K PRL is less than 10% of the total, these three patients had 150K PRL fractions of 97%, 96%, and 67%. The retention of normal menses and fertility of these subjects suggested that the 150K PRL had diminished biologic activity as patients with elevations of 22K PRL will have amenorrhea and infertility. Over time, the serum PRL levels of these three patients decreased with a coincident fall in the percentage of 150K PRL. Although serum thyroid concentrations usually influence serum PRL levels, no such effects were seen in these patients whether they were hypothyroid or hyperthyroid, neither was a causal relationship between the macroprolactinemia and autoimmune thyroid disease established. Macroprolactinemia cannot be considered to be a completely benign condition as occasionally it may be associated with infertility and osteopenia.
An automated interferometer for the analysis of anaesthetic gas mixtures.
A microprocessor-controlled interferometer is described. The eyepiece of a conventional Jamin type interferometer has been replaced by an array of photocells which records the intensity across the interference pattern. Mathematical correlation procedures are used to locate the principal interference pattern maximum and, by sequential analysis of a fresh gas mixture followed by fresh gas plus vapour, it is possible to determine both oxygen and vapour concentrations. The instrument was used to analyse mixtures of oxygen and nitrous oxide and also oxygen, nitrous oxide plus halothane. It was found that the oxygen concentration could be determined to an accuracy of +/- 1% v/v and the vapour concentration to +/- 0.1% v/v. The instrument is suitable for monitoring concentrations delivered by an anaesthetic machine and may be included in a microprocessor-controlled anaesthetic machine.
Comparison of event rates among three MONICA centres.
Data from three MONICA centres in Auckland (New Zealand) and Newcastle and Perth (Australia) are used to explore some of the issues involved in comparing event rates and case fatality among MONICA centres. Auckland and Newcastle follow the "hot pursuit" method of identifying and interviewing patients while they are still in hospital. Perth follows the "cold pursuit" method, in which patients are identified by search of computerized hospital records after discharge and all data are abstracted retrospectively from case notes. Fatal cases are identified by the same method in the three centres. The distribution of events by MONICA diagnostic classification varied among centres, with Perth having the highest proportion of definite myocardial infarction events and the lowest proportion of possible myocardial infarction events. These differences appear to be due to the different methods of event ascertainment and data collection, and to variations in post mortem rates between centres. For comparisons among these three centres, the categories of non-fatal definite myocardial infarction and of all coronary heart disease deaths (that is those in the MONICA categories fatal definite myocardial infarction, fatal possible myocardial infarction, and fatal cases with insufficient data) appear to be the most useful.
The pancreas in idiopathic Addison's disease--a search for a prediabetic pancreas.
Autopsy pancreases were studied from 14 patients who had idiopathic Addison's disease. One patient had been diabetic for 12 years and three patients were found to be diabetic during their terminal admission. While there was no evidence of diabetes or destruction of insulin-secreting beta cells in the remaining 10 patients, islets in one pancreas exhibited many of the histological and immunohistochemical features seen in the patients with recent onset diabetes. These included the presence of alpha-interferon in endocrine cells, hyper-expression of class I major histocompatibility complex molecules by endocrine cells in islets where alpha-interferon was also present, aberrant expression of class II major histocompatibility complex molecules by endocrine cells and the presence of insulitis. Since the combination of these changes has only been described in type 1 diabetes it is thought that the appearances seen in this pancreas were those of prediabetes.
Acne therapy (1934-1949). A review of 50 records.
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