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Biomedical subjects

M S Hobbs

Publications and source records attributed to M S Hobbs.

At least 37 records · Page 2Linked to original sources
PubMed1993

Radiographic abnormalities and mortality in subjects with exposure to crocidolite.

Plain chest radiographs from a one in six random sample of the workforce of the asbestos industry at Wittenoom, Western Australia between 1943 and 1966 have been classified for degree of profusion and pleural thickening by two independent observers according to the 1980 UICC-ILO Classification of Radiographs for the pneumoconioses to clarify the effect of degree of radiological abnormality on survival. A total of 1106 subjects were selected. Each subject's age, cumulative exposure to crocidolite, and time since first exposure were determined from employment records, the results of a survey of airborne concentrations of fibres > 5 mu in length conducted in 1966, and an exposure rating by an industrial hygienist and an ex-manager of the mine and mill at Wittenoom. By the end of 1986 193 subjects had died. Conditional logistic regression was used to model the relative risk of death in five separate case-control analyses in which the outcomes were deaths from: (1) all causes, (2) malignant mesothelioma, (3) lung cancer, (4) asbestosis, and (5) other causes excluding cancer and asbestosis. Up to 20 controls per case were randomly chosen from all men of the same age who were not known to have died before the date of death of the index case. After adjustment for exposure and time since first exposure, there were significant and independent effects of radiographic profusion and pleural thickening on all cause mortality. The effect of profusion was largely a result of the effect on mortality from malignant mesothelioma and asbestosis but not lung cancer. The effect of pleural thickening was greatest on mortality from other causes, mainly ischaemic heart disease. This study has shown that degree of radiographic abnormality has an independent effect on mortality from malignant mesothelioma, asbestosis, and all causes even after allowing for the effects of age, degree of exposure, and time since first exposure.

Asbestos, Crocidolite↗
PubMed1993

Coronary heart disease case fatality in four countries. A community study. The Acute Myocardial Infarction Register Teams of Auckland, Augsburg, Bremen, FINMONICA, Newcastle, and Perth.

BACKGROUND: Community-based registers participating in the MONICA Project of the World Health Organization show markedly different attack and death rates of coronary heart disease. This variation is a function of both the incidence and case fatality occurring within countries. The contribution of case fatality to the international variation in coronary heart disease mortality rates is not well understood. METHODS AND RESULTS: The register data from eight study populations--Augsburg and Bremen in Germany, Auckland in New Zealand, Perth and Newcastle in Australia, and North Karelia, Kuopio, and Turku/Loimaa in Finland--were compared. All patients with definite myocardial infarction or coronary death aged 35 to 64 years occurring in the study populations in 1985 through 1989 are the basis for the case fatality calculations by different definitions: 28-day case fatality for all cases, for hospitalized cases, and for hospitalized 24-hour survivors; out-of-hospital case fatality; and 24-hour case fatality for hospitalized cases. Differences in case fatality were much smaller than differences in attack and mortality rates in these populations. About two thirds of deaths occurred before the patients reached a hospital. The 28-day case fatality ranged from 37% for men in Perth to 58% for women in Augsburg. Among those who reached the hospital alive, 28-day case fatality was 13% to 27% for men and 20% to 35% for women. In those who survived 24 hours from the onset of symptoms, 28-day case fatality was 8% to 17% for men and 12% to 26% for women. CONCLUSIONS: Differences in case fatality were not associated with differences in coronary mortality rates between these populations. As most deaths occurred before reaching a hospital, opportunities for reducing case fatality through improved hospital care are limited. This emphasizes the primary role of prevention in reducing coronary death rates.

Adult↗
PubMed1992

Follow-up care after acute myocardial infarction.

OBJECTIVE: To examine the medical care received by patients following discharge from hospital after acute myocardial infarction (AMI). SETTING AND DESIGN: Community-based cross-sectional survey. PATIENTS: 2836 consecutive patients aged 25-64 years living in the Perth Statistical Division who were admitted to hospital with AMI during 1984-1988. After one reminder the response rate was 71%. RESULTS: Half of all respondents were in full-time employment at the time of their AMI. At follow-up this had fallen to a third. Over 80% of patients visited a cardiologist after AMI, with half remaining under consultant care to the time of survey. However, one in five patients reported no follow-up care at the time of survey. Seventy-three per cent of patients reported undergoing at least one exercise stress test after AMI, with 61% undergoing angiography, 16% angioplasty and 24% coronary bypass surgery. Large proportions of the patients accurately reported being prescribed beta-blockers and antiplatelet agents. The pattern of prescribing at discharge corresponded closely with the use of cardioactive agents at the time of survey and with drugs reported to have been taken continuously since discharge to the time of survey. CONCLUSIONS: These data suggest that follow-up care after AMI is both comprehensive and widespread. Such care may have contributed significantly to the overall decline in mortality from ischaemic heart disease.

Adrenergic beta-Antagonists↗
PubMed1992

Changing patterns of medical treatment in acute myocardial infarction. Observations from the Perth MONICA Project 1984-1990.

TYPE OF STUDY: Descriptive study of trends in the drug therapy for acute myocardial infarction. SETTING: Population-based register of acute coronary events compiled for the years 1984 to 1990 in the course of the Perth MONICA project. CASES: 5294 cases meeting clinical criteria for acute myocardial infarction. RESULTS: Striking changes were seen in the use of aspirin before admission to hospital (from 4% to 18%). During the stay in hospital the use of beta-blockers increased steadily from 52% to 76%, while the use of aspirin increased 3.5-fold from 25% to 88% and the use of streptokinase increased 13.5-fold from 2.4% to 32.4%. The proportion of patients prescribed beta-blockers on discharge from hospital increased from 46% to 65% and that for aspirin rose from 16% to 83%. There were also major relative increases in the use of lipid-lowering agents and declines in the use of antiarrhythmic drugs. CONCLUSION: These trends in the pharmacological management of myocardial infarction mirror the emerging evidence from clinical trials, although the increases in the use of certain types of drugs antedated publication of the results of major randomised studies. The changes in therapy would partly explain observed improvements in case fatality and may have contributed to the decline in coronary mortality observed in the Perth community.

Adrenergic beta-Antagonists↗
PubMed1992

A five-year study of residents of a special hostel for people with dementia.

In order to consider whether admission to a special hostel was a desirable policy in view of the likelihood of subsequent transfer to a nursing home, this study compared the time spent by residents in a special hostel with the period in a nursing home after they were transferred out of the hostel. We also estimated the number of nursing home places necessary for residents who were transferred and studied the reasons for transfer. The setting was a special hostel in Perth, Western Australia, for 36 people with moderate or severe dementia. The periods spent in the hostel or a nursing home were calculated for all residents admitted between 1985 and 1990. Forty-two of the 84 residents admitted during the study period were transferred to nursing homes. About two thirds of the total time in the two institutions was spent in the hostel. The two principal reasons necessitating transfer to a nursing home were advancing dementia and the addition of a physical impairment. Because a major proportion of the care of selected people with dementia (who can no longer remain at home) can be undertaken in a special hostel, this facility should be included with standard hostel and nursing home in arrangements for institutional care. Between 20 and 25 nursing home places are necessary for residents transferred from a hostel of this size.

Aged↗
PubMed1992

Historical trends in road accident types, deaths and casualties in Western Australia.

Road accident casualties are major consumers of health service resources in Australia, using inpatient care, accident and emergency treatment and other facilities. We analysed hospitalisations resulting from road accidents in Western Australia from 1968 to 1987 to examine trends in accident types, deaths and casualties. Data from the Western Australian Health Department's Hospital Morbidity System were used. Although hospitalisations from road accidents generally decreased, they were still higher than the Australian average in 1985. The rate of decline in hospitalisations was similar to that for fatalities and was not generally related to age or sex. There was some evidence of a more rapid decline in the rate of severe injuries than in minor ones. Further steps need to be taken to reduce the number of casualties from road accidents, as road accidents represent a major public health problem in Western Australia.

Accidents, Traffic↗
PubMed1991

Mortality from coronary heart disease and incidence of acute myocardial infarction in Auckland, Newcastle and Perth.

OBJECTIVE: To confirm the existence of regional differences in coronary death rates in Australia and New Zealand and to determine whether or not these are associated with parallel differences in the incidence of acute myocardial infarction. DESIGN: Descriptive epidemiological study. SETTING: Community based study. SUBJECTS: Residents of Auckland, Newcastle and Perth aged 25-64 years admitted to hospital for acute myocardial infarction or dying from coronary heart disease between 1983 and 1987. MAIN OUTCOME MEASURES: Definite acute myocardial infarction or coronary death classified according to the criteria of the World Health Organization MONICA project. RESULTS: This study confirms the marked variation, evident from official statistics, in mortality rates from ischaemic heart disease between Newcastle (high), Auckland and Perth (low). A different pattern is observed for the incidence of acute myocardial infarction and there are also obvious differences between centres in the case fatality ratios for all acute coronary events combined. Newcastle has the highest rate for all coronary events, particularly in women. Auckland is characterised by substantially higher case fatality ratios compared with the two Australian cities. This is due especially to higher rates of coronary death outside hospital. Perth, which has the lowest mortality rates and case fatality ratios in both men and women, has rates for admission to hospital for acute myocardial infarction and all cases of ischaemic heart disease that are disproportionately high in relation to the corresponding mortality rates. CONCLUSION: The differences in case fatality ratios between these three centres are not readily explained by artefacts related to enumeration or classification. Rather, they are most likely related to differences in the natural history of ischaemic heart disease in the three populations. Differences in medical management may also contribute to the substantial variation in mortality rates.

Adult↗
PubMed1991

The benefits of beta-blockade at the time of myocardial infarction.

Data from the World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease (WHO MONICA) project, collected in Perth, are described. Patients taking a beta-blocker at the time of onset of myocardial infarction are a high-risk group, but univariate analysis of the data showed that the overall survival of patients on beta-blockers at 28 days was the same as for those not taking beta-blockers. A multiple logistic regression model analysis showed that the patients treated with beta-blockers had a survival advantage at 28 days, with a relative risk of death of 0.5. The mechanism of benefit is unclear. It does not appear to be an anti-arrhythmic effect, because beta-blockers did not affect survival in the first 24 h following a myocardial infarction, nor did they affect ventricular fibrillation. The effect may be due to a reduction in myocardial necrosis. Furthermore, an analysis of the incidence of coronary disease and type of drugs prescribed in Perth has indicated that beta-blockers may be contributing to a decrease in mortality due to coronary events.

Adrenergic beta-Antagonists↗
PubMed1991

Risk factors for death in patients admitted to hospital with asthma: a follow-up study.

Hospital records of patients with asthma admitted to teaching hospitals in Perth, Western Australia between 1976 and 1980 were examined retrospectively to identify characteristics of the illness which were associated with subsequent death. From 5722 admissions there were 195 deaths to December 1982, 186 of whom had records available (cases); 452 of the surviving subjects were used for comparison (controls). There was no difference in age of onset of asthma or cigarette smoking habits between the two groups, but ischaemic heart disease as an associated condition was significantly more frequent in cases. On admission to hospital an arterial PCO2 less than 45 mmHg was more frequent in those who died, but there were no differences in arterial PO2, lowest pH, highest or lowest FEV1 and FVC. Cases more frequently used home nebulisers and were more frequently prescribed corticosteroids, antibiotics and sedatives or tranquilizers prior to admission, corticosteroids and sedatives or tranquilisers during admission and sedatives or tranquilisers on discharge. These results suggest that cases had more severe asthma in that they were more often treated with home nebulisers, corticosteroids and antibiotics, but with the exception of PaCO2 the commonly used measurements of severity of asthma did not identify those at risk of death. The prescription of sedatives or tranquillisers appears to be associated with an increased risk of death in subjects with asthma.

Adolescent↗
PubMed1991

Smoking, exposure to crocidolite, and the incidence of lung cancer and asbestosis.

In 1979 all former workers from the Wittenoom asbestos industry who could be traced to an address were sent a questionnaire to determine smoking history. Occupational exposure to crocidolite was known from employment records. Of 2928 questionnaires sent, satisfactory replies were received from 2400 men and 149 women. Eighty per cent of these had smoked at some time and 50% were still smoking. Since that time 40 cases of lung cancer and 66 cases of compensatable asbestosis have occurred in this cohort. The incidence of both lung cancer and asbestosis was greatest in those subjects with the highest levels of exposure to crocidolite and in ex-smokers. Statistical modelling of the joint effects of these exposures on the incidence of each disease indicated that crocidolite exposure multiplied the rates of lung cancer due to smoking and that smoking has no measurable effect on the rates of asbestosis. There was also some evidence that the incidence rate of lung cancer is falling with time.

Asbestos↗
PubMed1990

Reduced risk of death at 28 days in patients taking a beta blocker before admission to hospital with myocardial infarction.

OBJECTIVE: To see whether patients taking an oral beta blocker at the time of admission to hospital with myocardial infarction have a reduced risk of death at 28 days. DESIGN: Retrospective analysis of data collected on patients admitted over four years. SETTING: Community based study. PATIENTS: 2430 Consecutive patients living in the Perth statistical division admitted to hospital with myocardial infarction during 1984-7. MAIN OUTCOME MEASURE: Survival at 28 days among patients taking a beta blocker at onset of myocardial infarction. RESULTS: Patients were grouped into those who were and were not taking a beta blocker at the time of admission. Though patients taking a beta blocker were older and more likely to have a history of myocardial infarction, angina, or hypertension, the overall mortality at 28 days was similar in the two groups. A logistic regression model used to adjust for factors predictive of cardiac death at 28 days confirmed that patients taking a beta blocker at the time of admission had a significantly reduced risk of death (relative risk 0.50; 95% confidence interval 0.34 to 0.76). Though the incidence of fatal ventricular fibrillation was similar in the two groups, mean peak creatine kinase activity was significantly lower in the beta blocker group. CONCLUSIONS: These data support the value of long term use of beta blockers in patients at risk of myocardial infarction. They suggest that patients taking these agents before admission to hospital with myocardial infarction have a significant survival advantage at 28 days, which may be due to a reduction in infarct size.

Adrenergic beta-Antagonists↗
PubMed1989

The incidence of malignant mesothelioma in Australia, 1947-1980.

Details of patients with malignant mesothelioma that was diagnosed in Australia before 1981 were obtained by searching all possible sources throughout Australia as far into the past as possible and up to and including 1980. The earliest patient with mesothelioma who was identified was diagnosed in Victoria in 1947. By 1980, 535 (81%) men and 123 (19%) women had been diagnosed with the disease; only 14 persons were aged less than 35 years at the time of diagnosis (the youngest person was 15 years of age). The incidence rate in subjects who were 35 years or older at diagnosis was less than 1.0 cases per million person-years until 1964-1968, and then it rose progressively to 15.5 cases per million person-years in 1979-1980. The highest rate (69.7 cases per million person-years) was observed in 65- to 74-year-old men in 1979-1980. The incidence rate in Western Australia was greater than were the rates in other states of Australia after the mid 1960s. Pleural mesotheliomas accounted for 88% of cases in which the site of the tumour was known; peritoneal mesotheliomas accounted for 10% of such cases and "other" sites for 2% of such cases. In 6% of cases the site was not specified. The exposure to asbestos was stated as "definite" in 59% of the cases with a recorded history of exposure: 8% of all the cases in the study had been exposed to crocidolite (blue asbestos) from Wittenoom Gorge in Western Australia. The age at diagnosis of patients with known exposure to asbestos was similar to that in those without known exposure. The increases in the incidence of malignant mesothelioma in Australia follow the published trends in the production and use of the amphibole varieties of asbestos in this country after a lag period of between 20 and 30 years.

Adolescent↗
PubMed1989

Trends in the incidence of myocardial infarction in Western Australia between 1971 and 1982.

Trends in the incidence of and mortality from myocardial infarction in Perth, Western Australia, were studied for the period 1971 to 1982. The estimated age-adjusted incidence rate of myocardial infarction fell by 24% in males and 37% in females over this period. The rate fell in each of six age-sex groups, but the proportional decrease in those aged less than 45 years was nearly double that in those aged 45 years and over, as it was in females compared with males and in fatal cases compared with nonfatal cases. Over 80% of the decline in mortality was in deaths outside hospital. This and seven other comparable studies all showed a net decrease in the estimated incidence of myocardial infarction in both sexes, with median annual decreases of 2% in males and 3% in females. It is concluded that the decline in the incidence of myocardial infarction contributed substantially to the observed decrease in ischemic heart disease mortality, and that the most plausible explanation for the decline in incidence is a reduction in the prevalence of risk factors for myocardial infarction.

Adult↗
PubMed1989

Cancer mortality in relation to measures of occupational exposure to crocidolite at Wittenoom Gorge in Western Australia.

The separate and combined effects of duration and intensity of exposure to crocidolite on mortality from lung cancer, malignant mesothelioma, and stomach cancer were examined in 6506 male former crocidolite miners and millers at Wittenoom Gorge, Western Australia. Each subject who had died from lung cancer (92), mesothelioma (31), or stomach cancer (17) was matched with up to 20 control subjects of the same age who were not known to have died before the index subject. Relations of dose and time of exposure to crocidolite to risk of death were modelled by conditional logistic regression. For lung cancer, the best fitting multiplicative model was one which estimated a relative risk (RR) of 1.12 (95% CI 1.04-1.20) per year of exposure and 1.01 (95% CI 1.00-1.01) per fibre/ml. This was statistically indistinguishable from an additive model showing an increase in RR of 0.01045 (95% CI 0.008-0.020) per f/ml year. For mesothelioma the best fitting model appeared to be one estimating a RR of 24.9 (95% CI 3.51-1.77) per log year since first exposed and a RR of 10.5 (95% CI 3.12-35.1) if exposed for longer than six months. This was not distinguishable statistically from a model that showed mortality increasing as the fourth power of time since first exposed less the fourth power of time since last exposed. The effect of intensity of exposure on the RR for mesothelioma was only slight. There was no consistent effect of any measure of exposure to crocidolite on death from stomach cancer.

Asbestos↗
PubMed1989

CHD in Australia and New Zealand.

Death rates from coronary heart disease (CHD) have been declining in Australia and New Zealand for 20 years. Data from the three MONICA Project Centres in Newcastle (Australia), Perth (Australia), and Auckland (New Zealand) show similar trends for fatal CHD but differing trends for non-fatal myocardial infarction (MI). In Auckland, there has been a consistent decline in out-of-hospital death rates but no decline in non-fatal MI rates. In Perth, the greater contribution to the overall decline has been from out-of-hospital deaths, but in-hospital death rates and non-fatal MI rates have also declined. There is also some evidence of an increase in survival following MI in Perth. In Newcastle, both death rates and non-fatal MI rates have declined. The limited data available suggest that at least one-half of the decline in mortality can be attributed to improvements in population risk-factor levels. Improvements in medical management of both risk factors and established disease are also making contributions to the decline.

Adult↗
PubMed1988

Measuring the incidence of acute myocardial infarction: the problem of possible acute myocardial infarction.

Variations in the ratio of "definite" to "possible" myocardial infarction for non-fatal cases were examined in studies that used World Health Organization criteria. There were large variations in this ratio, variations which appeared to be due to differences in the ascertainment of non-fatal cases of "possible" myocardial infarction, which, in turn, contributed to reported differences in the incidence of myocardial infarction. A significant proportion of cases of "possible" myocardial infarction probably do not have ischemic heart disease at all, since, in our data, cases of "possible" myocardial infarction (non-fatal) with a hospital discharge diagnosis of chest pain (undiagnosed) had a risk of death that was no worse than that in the general population. Thus the most reproducible, and possibly most accurate estimates of the incidence of myocardial infarction may come from including only fatal cases of "possible" myocardial infarction with both fatal and non-fatal cases of "definite" myocardial infarction.

Acute Disease↗