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Biomedical subjects

M G McCall

Publications and source records attributed to M G McCall.

At least 19 recordsLinked to original sources

Atrial fibrillation and mortality in an elderly population.

Prospective data from Busselton, Western Australia, collected during triennial surveys from 1966-81 with follow-up of subjects to 1983, showed that atrial fibrillation (AF) was frequent in elderly people and associated with increased mortality. Of 1770 people aged over 60 years, 40 were in atrial fibrillation when first seen and a further 47 developed it during follow-up. Atrial fibrillation was positively associated with angina, history of a myocardial infarction and left bundle branch block. Relative mortality in those with atrial fibrillation compared with those without it, was 1.92 for all causes, 1.82 for death from cardiovascular causes (excluding stroke) and 3.78 for deaths from stroke, after adjustment by proportional hazards regression for confounding effects of age, sex, history of a myocardial infarction, an abnormal electrocardiogram, angina, cholesterol level systolic blood pressure and Quetelet's Index (weight/height2). The excess relative mortality declined with increasing age for both women and men. This raised relative mortality remained constant with time from the first detection of AF for all causes and cardiovascular causes but appeared to increase with time from detection for stroke death. The risk of death from stroke was greatest in the younger women. The observed risk of death from stroke in patients with AF suggests that anticoagulant use should be considered in selected patients.

Aged

The contribution of mortality statistics to the study of multiple sclerosis in Australia.

Mortality statistics provided a valuable source of support for data obtained from prevalence surveys of multiple sclerosis in Australia. Firstly, multiple sclerosis mortality data for the decade 1971-80 in the States of Australia confirmed the relationship between increasing disease frequency and increasing south latitude shown by State and regional point prevalence surveys based on the national census day 30 June 1981. Secondly, a comparison with mortality data from the decade 1950-59 showed that in most States there had been a substantial fall in multiple sclerosis mortality in the more recent decade and this was clearly an important contributing factor to the rise in prevalence noted between the morbidity surveys of 1961 and 1981. Thirdly, multiple sclerosis mortality in the UK-born migrant population dying in Australia was found to be similar to that of the Australian-born population and very much lower than that found in the UK. This observation corroborated evidence from the 1981 morbidity surveys and suggested that migration from the UK to Australia may lower the risk of developing multiple sclerosis either through a reduction in disease incidence or the operation of environmental factors curbing disease expression.

Australia

Levels of serum cholesterol, triglyceride, HDL-cholesterol, apoproteins A-I and B, and plasma glucose, and prevalence of diastolic hypertension and cigarette smoking in Papua New Guinea highlanders.

Coronary heart disease (CHD) is rare in Papua New Guinea (PNG) highlanders. Fifty-two men and 69 women randomly selected from three rural communities and a low socioeconomic urban community in the Eastern Highlands Province were assessed for hyperlipidemia, diabetes mellitus, diastolic hypertension and cigarette smoking. There was no significant difference between the findings in the rural and urban groups. The mean fasting levels of serum cholesterol, HDL cholesterol and apoproteins A-I and B were significantly lower (p less than 0.001) than those of rural Australians in a comparative study but the serum triglyceride levels were significantly higher in men less than 30 yr and women less than 40 yr of age. There was no significant difference in the serum cholesterol levels in men and women, and the levels of serum cholesterol and triglyceride did not rise with age. The mean fasting levels of plasma glucose were generally lower in PNG subjects and only two (1.7%) had diabetes mellitus. The proportions of highlanders who had diastolic hypertension or who smoked cigarettes were similar to those of Australian populations generally. The low incidence of CHD in PNG highlanders is probably related to the low serum cholesterol and apoprotein B levels, in turn probably related to their basically vegetarian diet and physically active life-style.

Adolescent

The epidemiology of multiple sclerosis in three Australian cities: Perth, Newcastle and Hobart.

An epidemiological survey of multiple sclerosis (MS) in three Australian cities, Perth, Newcastle and Hobart, was undertaken with its prevalence day being the national census day on June 30, 1981, exactly twenty years after a previous survey of the same cities. The relationship between increasing prevalence and increasing south latitude found in the 1961 survey was confirmed in this present study. Prevalence rates had increased significantly over the twenty years between the studies. Over the same time period incidence rates had also increased in Newcastle and Hobart but had remained essentially stable in Perth although these changes were not significant. The rise in prevalence was due to a combination of factors of differing importance in each city. These factors included better case ascertainment, increased recognition of the less severely disabled patient, increased survival time and differential immigration of a population at a higher risk of developing MS than the indigenous population. Finally, analysis of MS prevalence rates amongst migrant populations in Perth and Hobart suggested that either the risk of acquisition of MS may extend over a wider age range than is generally accepted or that environmental factors prevalent in the former city have modified disease expression there.

Age Factors

The clinical profile of MS in Australia: a comparison between medium- and high-frequency prevalence zones.

Recent epidemiologic studies of multiple sclerosis (MS) in Australia defined the State of Queensland as a medium-frequency zone and the more southerly placed cities of Perth, Newcastle, and Hobart as high-frequency zones. Clinical profiles in the patient populations of both frequency zones were remarkably similar in most respects to each other and to MS populations in the northern hemisphere. However, male patients in Queensland differed from their counterparts in the three cities by showing a greater tendency to develop a progressive disease course and, hence, more disability. The explanation for these observations is uncertain; we speculate that the hotter climate in Queensland may be relevant.

Adult

The epidemiology of multiple sclerosis in Queensland, Australia.

An epidemiological survey of multiple sclerosis (MS) in the State of Queensland was undertaken with its prevalence day being the national census day on June 30th, 1981, 20 years after a regional survey within the State. The relationship between increasing prevalence of MS and increasing south latitude within the State of Queensland which was suggested by the 1961 study was confirmed in the present study. The prevalence rate had increased significantly over the 20-year period between the studies but the State remained a medium frequency zone for MS (prevalence rate between 5 and 29 per 100,000 of population). Although a real increase in disease frequency could not be excluded as a contributing factor to the rise in prevalence, it was most likely due predominantly to an increase in life expectancy amongst the MS population and also in differential migration of a population at a greater risk of developing MS than the indigenous population. The proportions of Australian-born patients who had migrated to Queensland from the higher risk southern regions of Australia or travelled overseas to countries known to be high-risk for MS prior to disease onset, had fallen between the two surveys thus exerting, if anything, a negative influence on the change in prevalence. Analysis of MS prevalence rates amongst migrant populations in Queensland as compared to the more southerly city of Perth in Western Australia, suggested that the risk of acquisition of MS may extend over a wider age range than is generally accepted. Finally, there was an absence of MS cases amongst the Aboriginal population in Queensland but it can only cautiously be concluded from this study that the disease is rare in these peoples.

Adolescent

Changing mortality due to strokes in men following treatment of Busselton hypertensives 1967-77.

Regular biennial health screenings of the Busselton population between 1966-75 resulted in the recognition of individuals with hypertension and a progressive increase in the adequacy of control of blood pressure in those on treatment. Between 1973-77 observed mortality from strokes (CVA) in males 50 yrs and over declined significantly as might be expected from the smaller numbers at risk from raised blood pressure. No favourable trends occurred in the incidence of CVA in women despite better control of hypertension. In the population as a whole, CVA mortality in untreated or inadequately controlled hypertensives was significantly greater than in normo-tensives or adequately controlled hypertensives.

Age Factors

Community control of hypertension.

The adequacy of treatment of hypertension in a community was monitored at triennial mass health examinations. Hypertensives were not adequately retained on treatment until a disease register was developed and a practice nurse given responsibility for maintaining contact with patients on the register. The advent of newer therapeutic agents and intensification of the interest of both doctor and patient in the results of treatment were associated with progressive improvement in the adequacy of control of blood pressure.

Antihypertensive Agents

Acute myocardial infarction: one year follow-up of 1138 cases from the Perth Community Coronary Register.

The one year mortality of patients from the Perth Acute Myocardial Infarction Register surviving the acute episode (first 28 days) is presented. Of 1138 patients suffering definite or possible acute myocardial infarction in one year, 705 (62%) survived 28 days. There were 89 deaths (11-5%) in the subsequent 11 months. One year mortality was related to age but not sex, previous symptoms of coronary heart disease, but not hypertension or diabetes, to tachycardia and congestive cardiac failure at first examination, but not arrhythmias in the acute episode. These observations highlight the importance of protecting the myocardium in the acute phase of myocardial infarction.

Acute Disease

Borderline hypertension discovered during screening: effect of twelve months' treatment.

The frequency of borderline hypertension (diastolic BP 95 to 109 mm Hg) is described in 5,877 men and 1,125 women attending a screening clinic. Borderline hypertension is more frequent in each 5-year age group in men than women. The results of the initial 12 months treatment show a greater fall in mean systolic and diastolic pressures in those on active treatment in comparison with placebo. Over the same 12 months the sum of selected ECG precordial lead voltages shows a significant fall in those on active treatment as compared with those on placebo.

Adult

Lipoprotein electrophoretic patterns, serum lipids, and coronary heart disease.

Lipoprotein electrophoresis was performed on serum from subjects with and without coronary heart disease, and the patterns compared with the serum concentrations of triglyceride and cholesterol. The beta- and pre-beta-lipoproteins, expressed as a percentage of the total lipoprotein, correlate strongly with the cholesterol and triglyceride concentrations, respectively. The beta- and pre-beta-lipoprotein concentrations are even more strongly correlated with these lipid measurements. The lipoprotein pattern does not have greater discriminant value for coronary heart disease than does the triglyceride or cholesterol concentration. There would seem to be little justification for the use of lipoprotein electrophoresis in screening the general population for coronary heart disease.

Adult