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Biomedical subjects

N Pearce

Publications and source records attributed to N Pearce.

At least 37 records · Page 2Linked to original sources
PubMed1992

Cardiovascular effects of fenoterol under conditions of hypoxaemia.

BACKGROUND: The reason for the association of increased risk of death with fenoterol in patients with asthma in New Zealand is unknown but may relate to its cardiovascular effects. Most deaths from asthma occur outside hospital, where hypoxaemia is likely to be a complicating factor. The cardiovascular effects of fenoterol have been investigated therefore under conditions of normoxaemia and hypoxaemia. METHOD: Eight healthy men were studied on two occasions. Measurements of heart rate, blood pressure, total electromechanical systole (QS2I), electrocardiographic QTc interval, cardiac index, stroke volume, and ejection fraction were made under conditions of normoxaemia and hypoxaemia (arterial oxygen saturation 90%) before and after administration of 800 micrograms of fenoterol by a metered dose inhaler. The order in which treatments were applied was according to a Latin square design. RESULTS: Before inhalation of fenoterol hypoxaemia was associated with a significant increase in heart rate (8 beats/min) and QTc interval (15.6 ms). Under conditions of normoxaemia fenoterol caused a significant increase in heart rate (14.3 beats/min), systolic blood pressure (7.7 mm Hg), stroke volume (27.7 ml), cardiac index (1.6 1/min/m2), ejection fraction (11.48), and QTc interval (32.9 ms) and a fall in QS2I (-23.2 ms) and diastolic blood pressure (-8.4 mm Hg). Under conditions of hypoxaemia the changes after inhalation of fenoterol were similar to those recorded during normoxaemia; thus the effects of hypoxaemia and fenoterol were additive (heart rate 21.9 beats/min, QTc 43.5 ms with fenoterol and hypoxaemia). CONCLUSION: The chronotropic and electrophysiological effects of fenoterol were enhanced by conditions of hypoxaemia.

Adult↗
PubMed1992

Methodological problems of time-related variables in occupational cohort studies.

In studies of long-term health effects of occupational exposures it is important that the time patterns of the study exposure and of the relevant confounders should be taken into account in the analysis. The time-related confounders that have been most frequently considered include age at risk, calendar period, duration of employment, length of follow-up, and employment status (active or retired). These factors are related to the healthy worker effect which is more pronounced among active workers, and declines with length of follow-up. Thus, these time-related factors are potential confounders in occupational cohort studies (and in nested case-control studies). It is therefore advisable to routinely control for length of follow-up and employment status, in addition to the usual confounding factors of age at risk and calendar period. However, it should be stressed that this approach will minimise, but not eliminate, confounding due to the healthy worker effect. In particular, direct control for employment status is inadvisable if this constitutes an intermediate variable in the pathway between exposure and disease, and more complex analytical procedures are necessary in such situations. It is also important that the principle exposure under study should also be analyzed in a time-related manner, taking account of the likely induction and latency periods, and the relative etiological importance of exposure intensity, exposure duration and cumulative exposure. The simplest approach is to analyse the cumulative exposure in a time-related manner, and this may suffice when the aim is merely to consider whether or not there is an effect of exposure. However, once it has been provisionally assumed that an effect exists, attention then shifts to understanding the nature of the effect. In this context, the temporal pattern of exposure and outcome can be considered by examining the effects of exposures in specific time windows while controlling for time-related confounders, and for the effects of exposures in other time windows. A more sophisticated approach is direct fitting of a theoretical model of carcinogenesis, such as the Armitage-Doll or Moolgavkar models. However, it should be emphasized that occupational cohort studies only rarely have sufficient numbers, and data of sufficient quality, to permit meaningful conclusions to be drawn from more sophisticated analyses of this type.

Age Factors↗
PubMed1991

Undiminished social class mortality differences in New Zealand men.

Social class mortality differences in New Zealand men aged 15-64 years have previously been examined for the period 1975-7. It was found that the lower social classes had mortality rates higher than the upper social classes with the mortality rate of the lowest class being approximately twice that of the highest class on a six category scale. The greatest relative social class differences were in men aged less than 35 years. The analysis has now been repeated for the period 1985-7. Mortality declined by 15% between 1975-7 and 1985-7, but the social class mortality differences were undiminished, and the mortality slope was actually slightly greater in the more recent time period. The primary significance of social class analyses is that they identify groups in the community which have an excess mortality that is potentially preventable. The findings of this study indicate that this potential has not been fully realised in New Zealand, since social class differences are undiminished despite the continuing decline in overall mortality.

Adolescent↗
PubMed1991

Stomach cancer in New Zealand: time trends, ethnic group differences and a cancer registry-based case-control study.

Stomach cancer trends in New Zealand were examined. Age-standardized mortality and incidence rates have declined over the past four decades, as in other countries. Rates have been consistently higher for men, and for Maori. A cancer registry-based case-control study of 1016 male stomach cancer cases and 19,042 male controls with other cancers was also conducted, to evaluate the relationships between stomach cancer and specific occupations. Adjustment was made for age, ethnicity, socioeconomic level, and smoking status. When 22 occupational groups were examined, adjusted odds ratios (ORs) and 95% confidence intervals (95% Cls) were elevated above unity for only one group: forestry workers (OR 1.83, 95% Cl 1.01-3.32). When two large, heterogeneous groups were broken down into 15 subgroups, adjusted ORs and 95% Cls elevated above unity were found for three sub-groups: grain millers and related workers; brewers, wine and beverage makers; and field crop workers. These findings may be because of the multiple comparisons and subgroup analyses undertaken. Men who had ever smoked cigarettes were found to have an increased stomach cancer risk compared to those who had never smoked (adjusted OR 1.36, 95% Cl 1.15-1.60).

Case-Control Studies↗
PubMed1991

Social class inequalities in the decline of coronary heart disease among New Zealand men, 1975-1977 to 1985-1987.

Coronary heart disease (CHD) is regarded as a disease of developed 'western' societies. Within developed societies, however, CHD is typically a disease of the less affluent socioeconomic classes. This has not always been the case. Forty years ago. CHD was reported to be more common among the upper social classes. In New Zealand, as in other developed countries, this original trend across social classes was reversed during the past 40 years. In 1975-1977, a gradient across social class was observed for both CHD and cerebrovascular disease mortality, with the lowest social classes experiencing the highest mortality. This study has now been repeated for the period 1985-1987. Employed males aged 15-64 years were categorized by the Elley-Irving scale into six social classes. The overall age-standardized mortality rate from CHD declined over the ten-year period, from 163.0 to 121.7 per 100,000 person-years. Over the same period, however, the social class gradient for coronary mortality actually increased. The overall age-standardized mortality rate from cerebrovascular disease also declined over the ten-year period, from 25.9 to 17.7 per 100,000 person-years. A social class gradient for cerebrovascular mortality was present in both periods. In contrast to coronary mortality, however, the social class gradient diminished slightly over the ten-year period.

Adolescent↗
PubMed1991

Prescribed fenoterol and death from asthma in New Zealand, 1981-7: a further case-control study.

The association between inhaled fenoterol and death from asthma has been investigated further by studying 112 asthma deaths (cases) during 1981-7 in patients aged 5-45 years who had been admitted to a major hospital for asthma during the 12 months before death. Two age matched control groups were chosen. Control group A comprised 427 patients who had been admitted to hospital for asthma during the calendar year that the corresponding death occurred and who had also had a previous admission for asthma in the previous 12 months. Control group B comprised 448 patients admitted to hospital for asthma during the calendar year in which the admission of the corresponding case occurred. The inhaled fenoterol odds ratio was 2.11 (95% confidence interval (CI) 1.37-3.23, p less than 0.01) when group A was used as the control (the approach used in previous studies), and 2.66 (95% CI 1.74-4.06, p less than 0.01) with group B as the control (the approach recommended by critics of previous studies). Markers of chronic asthma severity were associated with asthma death when control group B was used, but not when control group A was used (which indicates that these markers were indirectly matched for when control group A was used). Information was also collected on various markers of acute asthma severity and prescription of psychotropic drugs, but it was found that these were not important confounders. These findings address the major criticisms of previous case-control studies of this issue, and add support to the hypothesis that inhaled fenoterol increases the risk of death in patients with severe asthma.

Administration, Inhalation↗
PubMed1991

Lack of evidence for beta-2 receptor selectivity: a study of metaproterenol, fenoterol, isoproterenol, and epinephrine in patients with asthma.

In order to investigate the pharmacodynamic selectivity of a number of beta-receptor agonists currently used in asthma, we compared the pulmonary and extrapulmonary effects of repeated inhalations of epinephrine, fenoterol, isoproterenol, and metaproterenol in 12 patients with asthma in a randomized double-blind crossover study. The drugs were administered from metered-dose inhalers at 15-min intervals for five doses (total dose, 10 puffs of each compound). Measurements of heart rate, blood pressure, total electromechanical systole (as a measure of inotropic response), QTc interval, plasma potassium, and FEV1 were made 5 min after each dose and 30 min after the final dose. Fenoterol and metaproterenol had significantly greater inotropic, electrocardiographic, chronotropic, and hypokalemic effects than did both isoproterenol and epinephrine. There was no difference in the bronchodilating effect of metaproterenol, fenoterol, or isoproterenol although these agents caused a significantly greater increase in FEV1 than did epinephrine. The concept of increasing beta-2 selectivity for metaproterenol and fenoterol compared with isoproterenol are not supported in the clinical setting.

Adrenergic beta-Agonists↗