Showing papers by "Neil Pearce published in 1993"

Self-reported prevalence of asthma symptoms in children in Australia, England, Germany and New Zealand: an international comparison using the ISAAC protocol

Abstract: There is a need for a standardized approach to international and regional comparisons of the prevalence and severity of asthma, and for the monitoring of asthma morbidity over time. In 1991, standardized written and video questionnaires were developed and administered in surveys of schoolchildren, aged 12-15 yrs, in five regions in four countries: Adelaide, Australia (n = 1,428); Sydney, Australia (n = 1519); West Sussex, England (n = 2,097); Bochum, Germany (n = 1928); and Wellington, New Zealand (n = 1863). The self-reported prevalence of wheezing during the previous 12 months was similar in West Sussex (29% using the written questionnaire and 30% using the video questionnaire), Wellington (28 and 36%), Adelaide (29 and 37%), and Sydney (30 and 40%), but was lower in Bochum (20 and 27%). The one year prevalence of severe wheezing limiting speech was greater in Wellington (11%), Adelaide (10%) and Sydney (13%), than in West Sussex (7%) and Bochum (6%). The self-reported one year prevalences of frequent attacks, frequent nocturnal wheezing, and doctor diagnosed asthma, were also higher in the Australasian centres than in the European centres. We conclude, that an international comparison of asthma symptom prevalence in childhood, using simple standardized instruments, is feasible. Possible explanations for the differences in reported asthma severity between the Australasian and European centres include differences in exposure to risk factors and differences in the management of asthma.

What Does the Odds Ratio Estimate in a Case-Control Study?

Abstract: The use of the term 'odds ratio' in reporting the findings of case-control studies is technically correct, but is often misleading. The meaning of the odds ratio estimates obtained in a case-control study differs according to whether controls are selected from person-time at risk (the study base), persons at risk (the base-population at risk at the beginning of follow-up), or survivors (the population at risk at the end of follow-up). These three methods of control selection correspond to estimating the rate ratio, risk ratio, or the odds ratio respectively, by means of calculating the odds ratio in the subjects actually studied. None of these estimation procedures depends on any rare disease assumption. Where the rare disease assumption is relevant is whether the effect which is estimated (e.g. the odds ratio) is approximately equal to some other effect measure of interest (e.g. the risk ratio or rate ratio) in the underlying study base. To avoid confusion on this issue, authors should be encouraged to not only specify the manner in which controls have been selected (e.g. by density sampling) but also the corresponding effect measure which is being estimated (e.g. the rate ratio) by the 'odds ratio' which is obtained in a case-control analysis.

A comparison of the cardiovascular and metabolic effects of formoterol, salbutamol and fenoterol

Abstract: The cardiovascular and metabolic effects of the long-acting beta 2-agonist formoterol were compared with those of salbutamol, fenoterol and placebo in 12 healthy volunteers, using a randomised, double-blind, cross-over design. On the study days, the subjects inhaled either formoterol (24 micrograms), salbutamol (400 micrograms), fenoterol (400 micrograms) or placebo, at 30 min intervals for five doses. Heart rate (HR) total electromechanical systole (Q-S2I) (a measure of inotropy), the corrected QT interval (QTc), systolic and diastolic blood pressure, plasma glucose and plasma potassium (K+) were measured prior to drug administration, 10 min after each inhalation and at 30 min intervals for 3 h after the last inhalation. All of the active agents significantly increased HR, QTc and plasma glucose, and decreased Q-S2I, diastolic blood pressure and plasma K+ compared to placebo. Fenoterol had a significantly greater maximum effect on HR, QTc and Q-S2I than either salbutamol or formoterol. Formoterol and fenoterol caused a similar maximum reduction in plasma K+, greater than that due to salbutamol. We conclude that formoterol is a more selective beta 2-agonist than fenoterol, and has similar cardiovascular effects to salbutamol when inhaled repeatedly by normal volunteers.

Descriptive epidemiology of primary cancer of the brain, cranial nerves, and cranial meninges in New Zealand, 1948–88

Abstract: We used New Zealand data on occurrence of different types of brain cancer to investigate: (i) a possible secular increase which has been seen worldwide and has generated considerable debate; (ii) possibly higher rates among Maori; and (iii) possibly higher risks related to social class and occupation. Data from the NZ Cancer Registry on the 5,684 brain cancers diagnosed among NZ residents from 1948–88 were used to study the pattern of occurrence by gender, age, race, calendar year, social class, occupation, and histology. Agestandardized brain-cancer incidence rates per 100,000 more than doubled over the 41-year period (from 2.9 to 6.9 in males and from 2.1 to 5.1 in females). A strong trend of increasing incidence with increasing social class is seen in males (P trend=0.01). Among Maori, the proportion of all brain cancer that is medulloblastoma is four times that among non-Maori, and the proportion of all brain cancers that lack histologic confirmation is about 40 percent higher. Elevated risks are seen among: dairy farmers (odds ratio [OR]=3.4, 95 percent confidence interval [CI]=1.9–6.0); sheep handlers (OR=2.7, CI=1.4–5.3); livestock workers (OR=3.8, CI=1.7–8.4); and farm managers (OR=3.2, CI=1.4–7.2); as well as among electrical engineers (OR=8.2, CI=20–34.7); electricians (OR=4.6, CI=1.7–12.2); and other electrical workers. Brain cancer rates in NZ have increased steadily since 1948, but this increase has leveled off in the most recent five-year period. Although brain cancer rates are likely to be underestimated among the Maori, an excess of medulloblastoma is evident in this group.

Occupational physical activity and risk of cancer of the colon and rectum in New Zealand males.

Abstract: The association between occupational physical activity and risk of colorectal cancer by age and anatomic site was investigated in a study of 2,503 males with colorectal cancer registered with the New Zealand Cancer Registry during 1972-80. Occupational groups that involved high levels of physical activity or were predominantly sedentary were identified prior to analysis of the registry data. Relative to males in high physical activity occupations, males in sedentary occupations had an increased incidence of both cancer of the colon (relative risk [RR] = 1.2; 95 percent confidence interval [CI] = 1.0-1.4) and rectum (RR = 1.3, CI = 1.0-1.5). The RRs for sedentary workers were particularly elevated in the 35-44 and 45-54 year age-groups for colon cancer (RR = 1.8 and 1.5, respectively) and in the 45-54 year age-group for rectal cancer (RR = 1.5), whereas there was no increase in risk for sedentary workers in the 55-64 year age-group for either cancer site. The general increase in colon cancer incidence for New Zealand during the study period was reflected in the sedentary group, but there was no change in incidence among men in occupations involving high or intermediate levels of physical activity. There was no obvious pattern for the increased cancer risk for men in sedentary occupations by anatomic site. Current physiologic hypotheses for the effect of physical activity on colon cancer risk do not adequately explain an association of physical activity with risk of rectal cancer.

Moderate maternal drinking and outcome of pregnancy

Abstract: The adverse effect of light or moderate maternal drinking during pregnancy on the well being of the newborn has been investigated. The study group included 2145 live births in the obstetric units of 11 Italian cities between February 1989 and July 1990. A detailed life style questionnaire was administered to the mothers. Information on the newborn was collected from clinical records as well as from a clinical examination. Both univariate and multivariate analyses were suggestive of a decrease in mean birth weight associated with maternal drinking during pregnancy, especially in women who also smoked during pregnancy. This effect was higher in male newborns. The occurrence of low birth weight (< 2500 g.) was more frequent in women drinking during pregnancy in both smokers and non-smokers (for this latter group an effect is suggested only for a daily consumption of more than 10 grams of absolute alcohol). Maternal alcohol drinking of more than 20 grams of absolute alcohol per day also increased the risk of preterm delivery (OR = 2.35; 95% CI: .98 – 5.59). Finally, an increase in the rate of early jaundice was found, also associated with maternal drinking (OR = 3.30; 95% CI: 1.03 – 10.54).

Social Class Differences in Mortality from Diseases Amenable to Medical Intervention in New Zealand

Abstract: Social class differences in mortality from causes of death amenable to medical intervention were examined. All deaths in New Zealand males aged 15-64 years during the periods 1975-1977 and 1985-1987 were identified. Strong social class gradients in mortality from causes of death amenable to medical intervention were observed during both periods. Furthermore, social class inequalities were more pronounced for amenable causes of mortality than for non-amenable causes. However, a marked decline in the age-standardized mortality rate from amenable causes was observed, with the rate falling by 30% over the 10-year study period. This decline was twice as large as the drop in the non-amenable mortality rate. Despite the fall in the death rate from amenable causes, social class inequalities in mortality persisted among New Zealand men, with the lowest socioeconomic group experiencing a death rate from amenable causes of mortality that was 3.5 times higher than men in the highest socioeconomic group.

Pathology of asthma and its clinical implications

Abstract: Although detailed histopathologic studies have described the inflammatory processes present in fatal asthma, until recently the pathology of less severe forms of the disease has been less well understood. Now a series of important studies has extended our understanding of the pathophysiology of mild asthma. Studies that examine sputum or fluid obtained by bronchoalveolar lavage from mildly asthmatic subjects revealed findings consistent with an active inflammatory process within the airways. The histopathologic examination of endobronchial biopsy specimens from stable asthmatic patients has shown that inflammatory cell infiltration of the mucosa is a distinctive feature of mildly asthmatic subjects requiring only intermittent inhaled beta-agonist therapy. These studies have also shown that marked tissue disruption may occur early in the natural history of mild asthma. These investigations have demonstrated that asthma is a disease characterized by acute and chronic inflammatory changes within the airways and that in many respects the histopathologic features of mild allergic asthma are similar to those observed in fatal asthma. The therapeutic implications of these findings are that management of mild asthma should be directed toward resolving this inflammatory process. There is now sufficient evidence to suggest that anti-inflammatory drugs such as cromolyn sodium, inhaled corticosteroids, and nedocromil sodium be used earlier in the course of the disease and that the use of these therapeutic agents should not be limited to patients with severe forms of asthma. This may be particularly important in view of the increasing awareness of the potential problems associated with the overreliance on beta-agonist therapy in patients with asthma.

Mortality and social class in Maori and nonMaori New Zealand men: changes between 1975-7 and 1985-7.

Abstract: Social class mortality differences in Maori and nonMaori New Zealand men aged 15-64 years have previously been examined for the period 1975-7. The analysis has now been repeated for the period 1985-7 in order to examine changes over time....Data were obtained from national death registrations and...from the 1976 to 1986 censuses....Some progress has been achieved in reducing ethnic differences in mortality in New Zealand men but substantial differences remain for diseases which are amenable to medical intervention (including chronic rheumatic heart disease hypertensive heart disease and tuberculosis). It is likely that these differences reflect poor access to culturally safe and appropriate health care in Maori people. (EXCERPT)

Chemical exposure in manufacture of phenoxy herbicides and chlorophenols and in spraying of phenoxy herbicides

Abstract: Exposure patterns are reported for manufacturing and sprayer cohorts incorporated in the "IARC International Register of Workers exposed to Phenoxy Herbicides and Contaminants." Information was based on company questionnaires, company reports, plant visits, and serum 2, 3, 7, 8-TCDD measurements. In addition to phenoxy herbicides and chlorophenols, workers in manufacturing plants may have been exposed to raw materials, process chemicals, other agents synthesized or formulated, and impurities of all these agents. Sprayers also had a complex exposure pattern, including phenoxy herbicides and some other pesticides, their carriers and additives, and residues of chemicals formed during manufacture. Occurrence of agents, including dioxins, varied between countries. Biological monitoring and industrial hygiene data were rarely available, most since the late 1970s. Exposure of workers depended mainly on the jobs they performed, but several factors influenced level of exposure. A quantitative exposure classification is not feasible in this study. Semiquantitative exposure estimates may be derived through a critical interpretation of biological monitoring and industrial hygiene data together with individual work histories.

Cancer incidence and mortality in women occupationally exposed to chlorophenoxy herbicides, chlorophenols, and dioxins.

Abstract: The association between exposure to chlorophenoxy herbicides contaminated with dioxins and occurrence of cancer has been studied mainly in male populations. In animal experiments, gender differences have been recorded in the cancer response to administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Mortality and cancer incidence in an international cohort of 701 women from an International Register of Workers occupationally exposed to chlorophenoxy herbicides, chlorophenols, and dioxins is examined. Cause-specific, national death rates and cancer incidence rates were used as referents. Cancer risk was not increased overall, with a standardized incidence ratio (SIR) of 96 and 95 percent confidence interval (CI) of 64–137, based on 29 cases. Among workers exposed to those chlorophenoxy herbicides contaminated with TCDD, excess cancer incidence (for all sites) was observed (SIR=222, CI=102–422, 9 cases); this was highest in the first 10 years after exposure. No excess was observed for breast cancer, the most common cancer in this cohort. Results on cancer mortality were consistent with those on incidence.

Prevalence of asthma symptoms among adolescents in the wellington region, by area and ethnicity

Abstract: AIMS: To compare the self-reported prevalence of asthma symptoms, among 12 to 15 year olds in three districts in the greater Wellington region, and to compare prevalence among three ethnic groups--Maori, Pacific Island and others. METHODS: Third form students from 13 secondary schools in the Wellington region, were surveyed using a video questionnaire and a standardised written questionnaire, during July 1991. RESULTS: Using the video questionnaire, the prevalence of wheeze during the previous 12 months was similar in Wellington city (32%), Lower Hutt (38%), and Porirua (37%); the corresponding findings using the written questionnaire were 28%, 27% and 30% respectively. The reported prevalence was also similar among Maori (38% using the video and 29% using the written questionnaire) and other children (36% and 30% respectively), but lower among Pacific Island children (31% and 20% respectively). The prevalence and frequency of severe attack of wheezing was similar in all three districts and all three ethnic groups. CONCLUSIONS: These findings contradict previous speculations of possible differences in asthma prevalence or severity within the greater Wellington region. They are consistent with other evidence that there are at most minor differences in asthma prevalence between Maori and nonMaori children in New Zealand; however, asthma prevalence may be lower among Pacific Island children. Thus ethnic differences in asthma morbidity and mortality are not likely to be due to differences in prevalence, but more likely relate to differences in access to and delivery of asthma care.

A comparative study of the efficacy of beclomethasone dipropionate delivered from a breath activated and conventional metered dose inhaler in asthmatic patients

Abstract: In order to overcome the problem of poor co-ordination with the use of the conventional press and breathe metered dose inhaler, a breath-activated inhaler ('Autohaler' inhalation device) has been developed. The clinical response to equal doses of beclomethasone dipropionate administered from the 'Autohaler' device and the conventional metered dose inhaler was compared in 36 stable asthmatic patients receiving regular inhaled beclomethasone dipropionate. The study was performed using a double-blind, double-dummy crossover design. Each treatment was given for 4 weeks. Objective and subjective measures of asthma severity were compared in the second 14 days of each treatment period, with clinical equivalence defined as a difference of 20% or less in the adjusted mean values for the 30 patients with data from both treatment periods. Equivalence at the +/- 5% level was found in the objective measures of pre-bronchodilator FEV1 (p < or = 0.001); post-bronchodilator FEV1 (p < 0.001); morning and evening peak expiratory flow rate (both p < or = 0.001). Patient diary cards established there was equivalent usage of inhaled bronchodilator, and equivalent symptom scores for daytime disability and daytime and night-time breathlessness. The results show that, in stable asthmatics, treatment with beclomethasone dipropionate is clinically equivalent when delivered by the 'Autohaler' device or the conventional metered dose inhaler used efficiently.

The Role of Beta Receptor Agonist Therapy in Asthma Mortality

Abstract: Preface. Historical Overview: The Development of Beta Receptor Agonist Drugs (S.R. O'Donnell). Studies of Time Trends in Asthma Mortality: A Century of Asthma Mortality (R.T. Jackson). Asthma Mortality Epidemics: The Problem Approached Epidemiologically (P. Stolley and T. Lasky). Analytical Epidemiological Studies of Beta Receptor Agonist Therapy and Asthma Mortality: Epidemiological Methods for Studying the Role of Beta Receptor Agonist Therapy in Asthma Mortality (N.E. Pearce and J.Crane). The New Zealand Case-Control Studies of Asthma Deaths Fenoterol: Interpratation and Clinical and Drug Regulatory Implications (J.M. Elwood). The Pharmacological Effects of Beta Receptor Agonist Drugs: An Overview of Experimental Methods (C.D. Burgess). The Role of Hypoxemia in Determining the Cardiovascular Response to Beta Receptor Agonist Drugs (R.G. Shanks). The Acute and Long-Term Effects of Beta Receptor Agonist Therapy: The Acute Unwanted Effects of Beta2 Receptor Agonist Therapy (M.J . Kendall and C.A. Haffner). The Long Term Effects of Beta Receptor Agonist Therapy in Relation to Morbidity and Mortality (C.S. Wong and A.E. Tattersfield). The Future: Long-Acting Inhaled Beta2 Receptor Agonist Drugs (K.F. Chung and P.J. Barnes). Asthma Mortality and Beta Receptor Agonists-A Perspective (J. Crane).