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Biomedical subjects

C A Silagy

Publications and source records attributed to C A Silagy.

48 records · Page 3Linked to original sources
PubMed1992

Is isolated systolic hypertension a 'white coat' phenomenon in the elderly?

1. Repeated clinic blood pressure measurement was compared with non-invasive ambulatory blood pressure (ABP) monitoring in 10 elderly subjects with isolated systolic hypertension (ISH) and 11 normotensive controls (NT). 2. Subjects were assessed on four occasions at weekly intervals. None was receiving antihypertensive or vasoactive medication. 3. Mean clinic blood pressure was consistently higher than mean daytime ABP in both clinical groups. This effect was greater for systolic (SBP) than diastolic blood pressure (DBP) and in the ISH group compared with the NT group. The reproducibility of the clinic minus ABP difference was high in both groups; the mean +/- s.d. of the differences was 26 +/- 15/9 +/- 2 mmHg in the ISH group and 7 +/- 18/8 +/- 9 mmHg in the controls. 4. ABP readings were normally distributed for both SBP and DBP in both groups. In the ISH group, the frequency distribution of SBP readings was shifted to the right whilst the distribution of DBP readings overlapped that of the NT subjects. 5. These results suggest a pressor response may largely account for the elevated SBP seen in elderly subjects with sustained ISH based on casual readings.

Aged↗
PubMed1992

Sample size requirements for clinical trials of isolated systolic hypertension.

1. This study investigated components of blood pressure variability in elderly subjects with isolated systolic hypertension (ISH) using both ambulatory blood pressure monitoring (ABPM) and casual clinic blood pressure measurement. These were then used to determine sample size requirements for clinical trials of different designs. 2. Eleven elderly subjects not receiving antihypertensive medication were seen on four occasions at weekly intervals. On each occasion blood pressure was measured in the clinic and then for 24 h using a non-invasive ABPM device. Nested analysis of variance was used to calculate the 'between subject' and 'between subject within occasion' components of blood pressure variability. 3. Increasing the number of readings or occasions where measurement was performed in a parallel group trial only reduced the variability substantially when the number of subjects involved was less than 50. Use of a cross-over design substantially reduced the sample size required. 4. ABPM appears most useful as a strategy for reducing sample size in parallel group trials in ISH involving small numbers of subjects measured on one occasion.

Aged↗
PubMed1992

An analysis of funding for general practice research in Australia.

OBJECTIVE: To describe the current status of funding for general practice research in Australia. DESIGN: A descriptive survey analysing funding arrangements of research projects included in a national research database, established by the Royal Australian College of General Practitioners. SETTING AND PARTICIPANTS: Research projects involving, or directly related to, general practice that had commenced in Australia since 1 January, 1989. Responses were specifically sought from all universities, the Family Medicine Programme and the Royal Australian College of General Practitioners. MAIN OUTCOME MEASURES: Extent and source(s) of funding received or requested, or both; relationship of funding received to the following: qualification and affiliations of the principal investigator; submission of the research project towards a higher degree; subject area(s) covered by the research; study design method used; and duration of project. RESULTS: A total of 237 projects from 130 principal investigators were included in the analysis. Of these, 149 (63%) had been submitted for funding and 98 (66%) had been successful. The amount of funding ranged between $300 and $855,600. The most common source of funding was the General Practice Evaluation Programme. Research contributing towards a higher degree was associated with successfully receiving funding. Other variables, including the study design and study area, were not significantly associated with an increased success of funding. CONCLUSIONS: The total amount of funds spent on general practice research is still small, relative to the size of the workforce. However, over half of general practice research undertaken in Australia is not submitted for funding. Of the research that is submitted, the success rate of receiving funds is high.

Australia↗
PubMed1991

Hypertension in the elderly: epidemiology and pathophysiology.

In all but a few remote and unacculturated tribes, blood pressure rises with advancing age. By the time Western adult males or females reach their 70s their probability of being hypertensive (BP greater than 140/90 mmHg) exceeds 50%. Unlike various other risk factors for vascular disease, hypertension retains its predictive power as age increases, but since the baseline risk is higher, the number of cases of disease attributable to hypertension is much higher in the elderly than in the young. The reason for the rise in blood pressure with aging is not well established, although a high lifetime intake of sodium may be a contributing factor. It now appears that the major hemodynamic abnormality is an increased peripheral resistance. It is possible that an accentuation of changes that take place with normal aging might be responsible for this phenomenon. They include a reduction in renal function, decreased baroreceptor sensitivity, or increased sympathetic activity. Up until the present time studies have been unable to isolate the mechanisms involved.

Age Factors↗
PubMed1991

Comparison of recruitment strategies for a large-scale clinical trial in the elderly.

Formal evaluation of recruitment strategies for clinical trials conducted in the community setting, rather than in hospitals, is limited despite recruitment rates and costs having significant implications for the planning of large trials. As part of the development of a large-scale primary prevention trial of low-dose aspirin in 15,000 elderly persons (aged 70 years and above) to be undertaken in a community setting, a pilot study involving 400 participants was carried out to evaluate different recruitment strategies. Three techniques were compared: recruiting from the electoral roll (by individual invitation using direct mail), local community approach (through retirement villages, local media, elderly community groups), and using general/family practice (identifying persons over 70 within a practice and direct mail invitation to participate). Screening of potential participants was carried out by a trained trial nurse with limited involvement only of medical practitioners. The target recruitment figure was achieved in 4 months using the equivalent of 1.5 full-time nurses. General practice was the most effective method utilized, with a yield of one participant recruited per six approached at an estimated cost of A$48.36 per recruited participant. This compares with yield rates of 1 per 29 (for the local community approach) and 1 per 17 for the electoral roll, and costs per participant of A$42.54 and A$59.37 respectively. Other less tangible benefits of general practice include the greater cooperation of primary care practitioners in patient follow-up and end-point ascertainment.

Aged↗
PubMed1991

Attitudes of senior medical students from two Australian schools towards rural training and practice.

Australia, like many other countries, continues to face a perennial shortage of doctors in rural areas. This 1988 study of final-year medical students at the two universities in Victoria, Australia, sought to assess their attitudes towards the choice of location for postgraduate training as well as ultimate practice location. The authors gave a cross-sectional, self-administered questionnaire to 360 students; 314 (87%) responded. The majority of the students expressed a desire to do their internships and postgraduate training in a metropolitan hospital. To identify the students' attitudes that might have influenced their choices, factor analysis was carried out. The "education and training" factor accounted for the highest percentage of the variance observed. As in most other similar studies, a strong relationship was observed between a student's rural background and the student's subsequent intention to train and work in a rural area.

Attitude to Health↗
PubMed1991

Rationale for a primary prevention study using low-dose aspirin to prevent coronary and cerebrovascular disease in the elderly.

The benefits of prophylactic aspirin therapy to prevent cardiovascular and cerebrovascular disease in asymptomatic individuals remains unclear. The rationale for developing a multicentered, double-blind, placebo-controlled clinical trial to determine whether low-dose aspirin (100 mg daily) prevents cardiovascular and cerebrovascular morbidity and mortality in persons aged 70 years and over with no evidence of pre-existing cardiovascular or cerebrovascular disease is described. Sample size calculations have indicated that 15,000 subjects would be required over a 4-year follow-up period in order to demonstrate a 20% reduction in overall cardiovascular mortality at the 0.01 level with a power of 0.8. Such a large-scale community-based clinical trial has never been conducted in Australia in this age group. Therefore the PACE (prevention by low-dose aspirin of cardiovascular disease in the elderly) pilot study has been developed to test recruitment strategies and methods and ascertaining disease end-points.

Adult↗
PubMed1990

A comparison of dilevalol and placebo in the management of isolated systolic hypertension using ambulatory monitoring.

1. The antihypertensive effect of dilevalol, a compound which combines beta-adrenoceptor blocking and vasodilating properties due to beta 2-adrenoceptor agonism, was studied in nineteen patients with isolated systolic hypertension (ISH). A randomized, double-blind, placebo-controlled, cross-over trial with two 4 week treatment periods was used to compare the efficacy of once daily dosing with dilevalol (in the range of 100-400 mg daily) against placebo. Assessment of response involved both casual blood pressure readings (amongst all patients) and 24 h ambulatory blood pressure monitoring (in ten of the nineteen patients). 2. A mean fall of 12/5 mm Hg (s.e. mean 3/2, P less than 0.05) and 9/3 mm Hg (s.e. mean 3/2, P less than 0.05) in supine and standing blood pressure respectively was observed with dilevalol. Mean heart rate was unchanged. The ambulatory monitoring profile demonstrated a smaller reduction in mean blood pressure (7/8 mm Hg) over the 24 h period and a reduction of 10/11 mm Hg over the daytime period. A blunting of the early morning increase in systolic pressure was observed with dilevalol. 3. The drug was well tolerated with light headedness and lethargy being reported more commonly than with placebo. Biochemical parameters were unaffected. 4. It is concluded that dilevalol in the doses used has a small but measurable antihypertensive effect as monotherapy in the treatment of ISH.

Aged↗
PubMed1990

Isolated systolic hypertension: does it really exist on ambulatory blood pressure monitoring?

1. The diagnosis of isolated systolic hypertension, diastolic hypertension and normotension in elderly subjects, as defined by casual office blood pressure measurement, was compared with 24 h ambulatory blood pressure monitoring using an Accutracker II. 2. Mean day-time ambulatory blood pressure monitoring underestimated the casual systolic blood pressure in all three clinical groups. Diastolic pressure was not underestimated to the same extent. 3. Ambulatory blood pressure monitoring best reflected casual blood pressure determination for normotensive subjects. In subjects with isolated systolic hypertension ambulatory blood pressures were only consistent with that diagnosis for 8% of the day time period. For 34% of the day time, their ambulatory blood pressures were consistent with diastolic/mixed hypertension. 4. It is concluded that isolated systolic hypertension may not be a sustained condition, but rather an isolated response to office measurement of blood pressure.

Age Factors↗
PubMed1989

Factors affecting the level of interest and activity in primary care research among general practitioners.

This paper presents the results of a state-wide survey of general practitioners in Victoria, Australia. The survey assessed their level of interest in general practice research as well as factors influencing the decision to participate in research. The study was conducted during the formation of a general practice research network which was being linked to a new primary care research unit in the Department of Community Medicine at Monash University. Of the 3350 general practitioners surveyed 1116 responded. One third expressed a high degree of interest in general practice research. Previous research experience and barriers to general practice research were also studied. The areas in which the doctors felt most research was required were identified. The results are compared with another study of Canadian family physicians, which is the only study of a similar nature previously published. The implications of the results are discussed with reference to the future direction of research by general practitioners.

Choice Behavior↗
PubMedDate not supplied

Garlic powder in the treatment of moderate hyperlipidaemia: a controlled trial and meta-analysis.

OBJECTIVE: To determine the effect of 900 mg/day of dried garlic powder (standardised to 1.3% allicin) in reducing total cholesterol. DESIGN: Double-blind, randomised six-month parallel trial. SUBJECTS: 115 individuals with a repeat total cholesterol concentration of 6.0-8.5 mmol/l and low-density lipoprotein (LDL) cholesterol of 3.5 mmol/l or above after six weeks of dietary advice. INTERVENTION: The active treatment group received dried garlic tablets (standardised to 1.3% allicin) at a dosage of 300 mg three times daily. The control group received a matching placebo. OUTCOME MEASURES: Primary end-point: total cholesterol concentration; secondary end-points: concentrations of LDL and high-density lipoprotein cholesterol, apolipoproteins (apo) A1 and B, and triglycerides. RESULTS: There were no significant differences between the groups receiving garlic and placebo in the mean concentrations of serum lipids, lipoproteins or apo A1 or B, by analysis either on intention-to-treat or treatment received. In a meta-analysis which included the results from this trial, garlic was associated with a mean reduction in total cholesterol of -0.65 mmol/l (95% confidence intervals: -0.53 to -0.76). CONCLUSIONS: In this trial, garlic was less effective in reducing total cholesterol than suggested by previous meta-analyses. Possible explanations are publication bias, overestimation of treatment effects in trials with inadequate concealment of treatment allocation, or a type 2 error. We conclude that meta-analyses should be interpreted critically and with particular caution if the constituent trials are small.

Analysis of Variance↗