Biomedical subjects
M R Sears
Publications and source records attributed to M R Sears.
Reduced selenium in asthmatic subjects in New Zealand.
Selenium is an essential component of glutathione peroxidase, an enzyme that helps protect cells against oxidation damage and modulates the lipoxygenase pathway of arachidonic acid metabolism. Low selenium concentrations might therefore influence the inflammatory process in asthma by reducing the activity of glutathione peroxidase. Whole blood and plasma selenium concentrations and glutathione peroxidase activity have been measured in 56 asthmatic patients and 59 non-asthmatic control subjects in New Zealand, a country with a low dietary selenium intake and a high prevalence of asthma. When compared with control subjects the asthmatic patients had lower values for whole blood selenium concentrations (-4.9, 95% confidence interval -10.2 to 0.4 ng/ml) and glutathione peroxidase activity (-3.3, 95% CI -5.8 to -0.8 units/g Hb). There was a 1.9 and 5.8 fold increased risk of asthma in subjects with the lowest range of whole blood selenium concentration and glutathione peroxidase activity respectively (95% CI 0.6 to 5.6 and 1.6 to 21.2). Levels were lower in patients and control subjects without an atopic predisposition, but were not affected by prednisone use. Similar differences between the asthmatic and control subjects were not observed for selenium concentration or glutathione peroxidase activity measured in plasma, which reflects short term rather than long term selenium content. These findings are consistent with the hypothesis that low selenium concentrations may have a role in the pathogenesis of asthma in New Zealand.
Fenoterol and fatal asthma.
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The relative risks of sensitivity to grass pollen, house dust mite and cat dander in the development of childhood asthma.
The associations between skin sensitivity to various common allergens and the development of childhood asthma were ascertained in a longitudinal study of a birth cohort of New Zealand children up to the age of 13 years. Of 714 children skin-tested, 45.8% were sensitive to at least one of 11 allergens, the most common responses being to rye grass pollen (32.5%), house dust mite (30.1%) and cat dander (13.3%). Allergen-specific relative risk analysis, controlled for the effect of sensitivity to other allergens, demonstrated that sensitivity to house dust mite and to cat dander were highly significant independent risk factors associated with the development of asthma (whether defined as recurrent typical respiratory symptoms, increased airway responsiveness, or the concurrent presence of both), whereas grass sensitivity was not a significant independent risk factor for asthma.
Prophylaxis for asthma.
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Asthma in New Zealand: some answers, more questions.
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Recurrent nocturnal near fatal asthma in a young man.
A young man who suffered multiple near fatal nocturnal asthmatic attacks, including at least three episodes of respiratory arrest, was found to be symptomatically unaware of marked increases in airway obstruction, and failed to perceive bronchoconstriction induced by methacholine challenge. Intensive antiasthma treatment monitored by regular peak expiratory flow measurements abolished the nocturnal attacks, which recurred twice when treatment lapsed. Patients prone to apparently sudden and life-threatening attacks of asthma may be at risk because of failure to perceive steadily worsening asthma.
Confidentiality and prescriptions.
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Increasing asthma mortality--fact or artifact?
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International trends in asthma mortality: 1970 to 1985.
Recent international trends in asthma mortality among people aged five to 34 years were examined as a follow-up to an epidemic of asthma deaths in the late 1970s which appeared to be confined to New Zealand. Mortality rates were compared in 14 countries with suitable statistics; Australia, Canada, England and Wales, Finland, France, Japan, Israel, the Netherlands, New Zealand, Singapore, Sweden, Switzerland, the United States, and West Germany, for the period 1970 to 1984/5. In New Zealand, asthma mortality in this age group more than trebled from 1.3 per 100,000 in 1974 to 4.2 per 100,000 in 1979 and since then has declined substantially to 1.85 per 100,000 in 1985. Asthma death rates vary more than six-fold among the other countries examined, and although the New Zealand experience has not been seen to the same degree elsewhere, a gradual increase in reported asthma mortality has occurred since the mid to late 1970s in the majority of countries studied. The increase and subsequent decline in asthma mortality in New Zealand could not be explained by changes in diagnostic fashions or in the International Classification of Disease coding rules. Similarly, the US data do not suggest there is diagnostic transfer among diseases of airway obstruction. However, part of the differences in asthma mortality among the countries examined and the recent increases in asthma death rates, could be due to changing diagnostic fashions rather than true differences in mortality. International studies on the validity of asthma death statistics and on asthma prevalence are required to clarify these issues.
How well do New Zealand patients understand and manage their asthma? A community study.
Patient understanding of the nature of asthma and of its management was assessed using an interviewer administered questionnaire in a community sample of asthmatics identified through prescriptions at randomly selected Dunedin city pharmacies. Of 135 subjects whose histories, and lung function data where available, were consistent with asthma, 20 did not know they had asthma. Only half could give a simple explanation of asthma, and many were confused about therapies, especially the use of corticosteroids. Only half demonstrated satisfactory aerosol inhalation technique. Deficiencies in medical management including lack of lung function monitoring, regular followup and provision of a crisis plan for severe attacks were noted. Patients previously hospitalised more often had a crisis plan and recalled advice on management of asthma, but had little knowledge about the nature of the condition. The continuing high asthma mortality rate in New Zealand may in part reflect management deficiencies both in long term care and in recognition and management of severe attacks. These may be compounded by poor patient understanding of asthma.
Emergency care of acute asthma.
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Some family social background, developmental, and behavioural characteristics of nine year old children with asthma.
Children with moderate and severe, mild, and trivial asthma were compared with a group of children who did not have asthma on a range of measures including family social background (socioeconomic status, family adversity, family environment), intelligence, reading, spelling, and behaviour. None of the background measures significantly differentiated among the groups. The group of children with moderate and severe asthma was found to have a significantly lower mean score for verbal intelligence, full scale intelligence, and spelling than those with mild asthma, but did not differ significantly from the remainder of the sample. Children with mild asthma were found to have slightly higher reading scores.
Lessons from the national asthma mortality study: deaths in hospital.
The circumstances surrounding 38 deaths from asthma in hospital in New Zealanders under 70 years of age between August 1981 and July 1983 have been analysed. Twelve deaths did not appear to be preventable, all but one occurring in chronic severe asthmatics despite apparently optimal therapy. Critical delays by patients or relatives in seeking medical help occurred in six cases, and inadequate assessment of severity and undertreatment by medical practitioners prior to the patient reaching hospital was a major contributing factor in a further six deaths. In four cases, insufficient speed and indecisive treatment in the accident and emergency department appeared to contribute to death. Ten patients died after many hours or days in hospital wards in circumstances where assessment, monitoring and treatment were deficient. There were no deaths in intensive care units. Urgent expert assessment is necessary in A & E departments, and more severe cases should be managed in intensive care units. Patients with acute severe asthma may need continuous oxygen, intravenous therapy and close objective assessment for a week or more after hospitalisation.
Asthma mortality: comparison between New Zealand and England.
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75 deaths in asthmatics prescribed home nebulisers.
The circumstances surrounding the deaths of 75 asthmatic patients who had been prescribed a domiciliary nebuliser driven by an air compressor pump for administration of high dose beta sympathomimetic drugs were investigated as part of the New Zealand national asthma mortality study. Death was judged unavoidable in 19 patients who seemed to have precipitous attacks despite apparently good long term management. Delays in seeking medical help because of overreliance on beta agonist delivered by nebuliser were evident in 12 cases and possible in a further 11, but these represented only 8% of the 271 verified deaths from asthma in New Zealanders aged under 70 during the period. Evidence for direct toxicity of high dose beta agonist was not found. Nevertheless, the absence of serum potassium and theophylline concentrations and of electrocardiographic monitoring in the period immediately preceding death precluded firm conclusions whether arrhythmias might have occurred due to these factors rather than to hypoxia alone. In most patients prescribed domiciliary nebulisers death was associated with deficiencies in long term and short term care similar to those seen in patients without nebulisers. Discretion in prescribing home nebulisers, greater use of other appropriate drugs, including adequate corticosteroids, and careful supervision and instruction of patients taking beta agonist by nebuliser should help to reduce the mortality from asthma.
Lessons from the national asthma mortality study: circumstances surrounding death.
The circumstances surrounding all deaths from asthma in New Zealanders under 70 years of age between August 1981 and July 1983 have been analysed from information recorded or recalled by doctors or relatives of the deceased. Factors which may have reduced the time available for effective treatment of these severe attacks are described to draw attention to ways in which mortality might be reduced. For almost half of the 271 deaths medical help had not been called before the patient was in extremis. When medical help was summoned in sufficient time doctors commonly did not give corticosteroids or used them inadequately. Difficulties in using medical care and noncompliance with asthma management were common particularly in Polynesian patients. In 38% of patients some medical inadequacy appeared to contribute to poor long-term care and education. Failure of patients to attend for ongoing medical care, education and preventative treatment, or a medical failure to deliver these may have led to chronically reduced lung function. Any further deterioration may then have more rapidly led to a fatal outcome. Lack of patient or family awareness about how to detect and cope with an unusually severe attack was found and contributed to avoidable fatalities.