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Biomedical subjects

S Kinlay

Publications and source records attributed to S Kinlay.

At least 55 records · Page 3Linked to original sources
PubMed1996

Cardiac event recorders yield more diagnoses and are more cost-effective than 48-hour Holter monitoring in patients with palpitations. A controlled clinical trial.

OBJECTIVE: To compare the diagnostic yield and cost-effectiveness of transtelephonic event monitors with those of Holter monitoring in patients with intermittent palpitations. DESIGN: Randomized crossover trial. SETTING: Diagnostic service of a teaching hospital and surrounding primary care practices. PATIENTS: 43 patients with previously uninvestigated palpitations who were referred for Holter monitoring. MEASUREMENTS: Patients were randomly allocated to receive an event monitor or 48-hour Holter monitor and then to receive the other device. Event monitors were used for 3 months or until two recordings were obtained while symptoms occurred. The main end point was an electrogram recorded during symptoms. The incremental cost-effectiveness of obtaining a diagnostic rhythm strip from event monitors was compared with that of Holter monitoring. RESULTS: The mean (+/- SD) patient age was 45 +/- 19 years; 37 patients (88%) were women. Event monitors were twice as likely to provide a diagnostic rhythm strip electrocardiogram during symptoms as 48-hour Holter monitoring (29 patients [67%] and 15 patients [35%], respectively; P < 0.001). Event monitors detected 8 patients (19%) with clinically important arrhythmias (6 patients with supraventricular tachycardia and 2 with atrial fibrillation or flutter), whereas the Holter monitors detected no significant arrhythmia (P < 0.005). With the event monitors, most patients transmitted an electrocardiogram recording by 6 weeks. Event monitors were dominant and therefore more cost-effective than 48-hour Holter monitoring, resulting in a cost savings of $213 for each additional diagnostic rhythm strip obtained during symptoms. CONCLUSIONS: Holter monitoring is a poor diagnostic test for intermittent palpitations. Event recorders provide better data and are more cost-effective.

Adult↗
PubMed1996

Risk of primary and recurrent acute myocardial infarction from lipoprotein(a) in men and women.

OBJECTIVES: This study sought to examine whether lipoprotein(a) concentrations were risk factors for a first acute and recurrent myocardial infarction. BACKGROUND: There is conflicting evidence concerning the risk of acute myocardial infarction from lipoprotein(a). No studies have examined the risk of recurrent acute myocardial infarction from lipoprotein(a), and few have addressed the risk in women. METHODS: This was a population-based case-control study of 893 men and women 35 to 69 years old participating in the World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease (MONICA) Project in Newcastle, Australia in 1993 to 1994. Case and control patients were classified into those with and without a previous myocardial infarction, and median lipoprotein(a) concentrations were compared after adjusting for other variables. Quintiles of lipoprotein(a) concentration were also examined. RESULTS: Compared with control subjects without a previous myocardial infarction, median lipoprotein(a) concentrations increased from case patients with a first myocardial infarction (15 mg/liter higher, 95% confidence interval [CI] -36 to 60) to control patients with a previous myocardial infarction (159 mg/ liter higher, 95% CI 40 to 278) and case patients with a previous myocardial infarction (60 mg/liter higher, 95% CI -16 to 136, p < 0.01, test for trend). Women had significantly higher lipoprotein(a) concentrations than men (median 71 mg/liter higher, 95% CI 23 to 118). The highest quintile of lipoprotein(a) (>550 mg/liter) was a significant risk factor for a first acute myocardial infarction (odds ratio [OR] 1.77, 95% CI 1.03 to 3.03); but in those with a previous myocardial infarction, the highest quintile was not associated with recurrent myocardial infarction (OR 0.84, 95% CI 0.30 to 2.37). CONCLUSIONS: High lipoprotein(a) concentrations may be a marker of vascular or tissue injury or may be associated with other genetic or environmental factors that cause acute myocardial infarction. Currently, lipoprotein(a) measurement cannot be recommended for assessment of risk for acute myocardial infarction.

Adult↗
PubMed1996

Biological mechanisms for the clinical success of lipid-lowering in coronary artery disease and the use of surrogate end-points.

The small changes in luminal narrowing observed with lowering total cholesterol are unlikely to be the principal mechanism by which lipid-lowering achieves a reduction in clinical events and revascularization rates. Endothelium dependent vasomotor function, and the cellular characteristics of plaques that seem to be intimately related to rupture and thrombosis, are factors that may explain the clinical success from correcting the dyslipidemias. Dyslipidemias cause endothelial dysfunction that predisposes to vasoconstriction of the epicardial coronary arteries and the resistance vessels relative to metabolic demand. Dysfunctional endothelium also promotes the recruitment of inflammatory cells into the vessel wall which contributes to the activation of vascular smooth muscle cells and sets up an environment within the plaque that predisposes to rupture and a prothrombotic state. Aggressive lowering of total cholesterol, and especially LDL and oxidized LDL, improves coronary endothelial function both of the epicardial and resistance vessels, and leads to a reduction in myocardial ischemia. Lipid-lowering may promote plaque stability in part by reducing the recruitment of inflammatory cells, and possibly by changing the size or consistency of the lipid-rich core of plaques. A thicker fibrous cap and stiffer plaque that is less likely to rupture may result, and in the event that rupture does occur, cholesterol lowering may reduce the formation of overlying thrombus. Testing coronary or peripheral artery endothelial vasomotor dysfunction may be a surrogate measure for assessing the effectiveness of interventions to prevent coronary heart disease. These tests are likely to be used increasingly to identify interventions that deserve greater attention in larger clinical trials, as well as providing mechanisms for any observed clinical benefits.

Animals↗
PubMed1996

Cost-effectiveness of coronary angioplasty versus medical treatment: the impact of cost-shifting.

BACKGROUND: Coronary angioplasty (PTCA) offers improved symptom control over medical treatment in patients with stable angina and single-vessel disease. However, it is uncertain if PTCA is more cost-effective. Cost-shifting could also influence the provision of PTCA. METHODS: Data from the only randomised trial comparing PTCA to medical therapy (ACME study) were used with costs from an Australian teaching hospital to estimate the costs and freedom from angina in 100 patients over three years. The incremental cost-effectiveness of PTCA, and the potential for cost-shifting were also examined. RESULTS: Although the total cost of treating 100 patients over three years with PTCA ($678,978) was higher than a medical strategy ($631,078), PTCA was more cost-effective ($10,930 versus $12,682 per patient free of angina). The incremental cost-effectiveness of PTCA ($3875 per extra patient free of angina) was also substantially less than the cost of the medical strategy. These should be considered crude estimates as they were based on limited data on resource use. The hospital could reduce costs by pursuing a medical strategy, but 54% of the savings would result from shifting the cost of treating patients to the Federal Government and patients. By performing PTCA on privately insured rather than Medicare patients, the hospital could shift $29,876 per 100 patients to the Federal government and private insurance funds. CONCLUSIONS: From society's perspective, PTCA may be more cost-effective than a medical strategy. However, the financial interests of the hospital are best served by limiting PTCA or restricting PTCA to privately insured patients. Cost-shifting may have a major impact on the provision of PTCA. The costs of providing medical services need to be weighed against the cost of not providing them.

Angioplasty, Balloon, Coronary↗
PubMed1995

Magnesium sulfate in the treatment of ventricular arrhythmias due to digoxin toxicity.

Although digoxin antibodies are the definitive treatment of cardiac arrhythmias due to digoxin toxicity, magnesium can also be effective especially with low serum magnesium levels. The case report describes a patient with digoxin toxicity, ventricular tachycardia and a slightly elevated serum magnesium. Two 10 mmol doses of intravenous magnesium sulfate were associated with a more stable junctional rhythm with bigeminy. Magnesium is known to suppress early after depolarizations, and in supraphysiological doses, may act as an indirect antagonist of digoxin at the sarcolemma Na(+)-K(+)-ATPase pump. Intravenous magnesium may be used to treat cardiac arrhythmias due to digoxin poisoning where there is likely to be a delay in the availability of digoxin antibodies, even in the presence of elevated serum magnesium.

Aged↗
PubMed1994

The cost-effectiveness of different blood-cholesterol-lowering strategies in the prevention of coronary heart disease.

We aimed to compare the cost-effectiveness of two screening strategies and a population strategy for lowering blood cholesterol to prevent coronary heart disease. Census data, known risk-factor profiles, known coronary heart disease event rates and costs in 1988-89 Australian dollars for all men aged 35 to 64 in the Lower Hunter region of New South Wales (n = 67,651) were used to compare a high-risk strategy identifying and treating men with cholesterol levels above 6.5 mmol/L with diet and drug (cholestyramine), a moderate/high-risk strategy where in addition diet counselling was offered to those with levels 5.5 to 6.5 mmol/L, and a population strategy where the diet of the whole population was changed regardless of blood cholesterol. Costs of implementing strategies, heart disease events saved, discounted and undiscounted cost-effectiveness ratios and savings in initial treatment costs over five years were measured. For the high-risk, moderate/high-risk and population strategies, the costs of implementation were $50.1m, $53.1m and $5.4m respectively; the numbers of events saved were 104, 144, 116 respectively; cost-effectiveness ratios were $482,224, $369,098, $46,667 (per event saved) respectively. Cost savings for each strategy were approximately half a million dollars. The moderate/high-risk strategy was more cost-effective than the high-risk strategy but the population strategy cost one-tenth that of the two screening strategies per event saved. More research is required to design and test strategies that alter the eating habits of the whole population.

Adult↗
PubMed1994

A new method of estimating cost effectiveness of cholesterol reduction therapy for prevention of heart disease.

The purpose of this study was to demonstrate a new method of estimating the cost effectiveness of interventions that lower blood cholesterol levels in the prevention of coronary heart disease (CHD) at the community level. The participants in the study were 67 651 men aged 35 to 64 years in the Lower Hunter region of New South Wales, Australia. Census data, risk factor profiles and CHD event rates from community surveillance, plus costs in 1988-1989 Australian dollars, were used as inputs to a computer program that used a logistic equation. The output estimated the CHD events avoided and the cost effectiveness of an intervention that identified and treated men with cholesterol levels greater than 6.5 mmol/L with dietary modification and cholestyramine. The cost of implementation of the intervention was $A50.1 million to prevent 104 CHD events. The cost-effectiveness ratio was $A482 224 per CHD event avoided (SD = $A24 761) and the direct medical costs avoided were approximately $A500 000 over a 5-year period ($A4535.07 per CHD event avoided). Drug acquisition costs contributed substantially (88%) to the total costs of interventions that rely on screening to identify individuals with high cholesterol for intensive treatment.

Adult↗
PubMed1992

The validity of estimating heart disease reduction from a Framingham logistic equation.

We compared two ways in which a logistic equation could be used to estimate the number of heart disease events prevented after lowering blood cholesterol levels. Men were selected from an Australian population survey who met the entry criteria of the Lipid Research Clinics Coronary Primary Prevention Trial (LRC-CPPT). The numbers of heart disease events expected over 7.4 years were calculated from the logistic equation after reducing the men's blood cholesterol by the amounts achieved in the LRC-CPPT placebo and treatment groups (our simulated placebo and treatment groups). The number of events prevented was calculated as the absolute difference between the simulated groups (9.48 per 1000 men per 7.4 years) and the percentage difference of the simulated groups multiplied by the observed incidence rate in the LRC-CPPT placebo group (13.66 per 1000 men per 7.4 years). The second estimate was closer to that observed in the LRC-CPPT (17.10 per 1000 men per 7.4 years), and we recommend this approach in cost-effectiveness studies.

Australia↗
PubMed1991

Lipid and apolipoprotein levels in an Australian community.

Serum levels of total and high density lipoprotein (HDL) cholesterol and apolipoproteins A1 and B were measured in over 600 men and women aged 30-69 years who were selected at random from an Australian community. Total cholesterol and apolipoprotein A1 and B levels increased with age, with this effect being most pronounced for total cholesterol and apolipoprotein B in women. Body mass index and waist-to-hip ratio were positively correlated with apolipoprotein B and total cholesterol levels, and negatively correlated with apolipoprotein A1 and HDL cholesterol levels. All lipid and apolipoprotein A1 levels increased with the quantity of alcohol consumed. After adjusting for age, body mass index and smoking, the association with alcohol was strongest for apolipoprotein A1 and HDL cholesterol levels in men (P = 0.0001), and for apolipoprotein A1 levels in women (P = 0.01). Levels of apolipoprotein A1 and HDL cholesterol were lower, and of apolipoprotein B and total cholesterol were higher, in current cigarette smokers than non-smokers, with significant associations for apolipoprotein B (P = 0.004) and HDL cholesterol levels (P = 0.04) in men. In general, the associations between apolipoprotein A1 levels and the other variables were weaker than those for HDL cholesterol levels, whereas the associations with apolipoprotein B levels were stronger than those for total cholesterol levels (except for alcohol consumption). Thus, obesity, alcohol consumption and cigarette smoking should be considered when interpreting apolipoprotein levels.

Adult↗
PubMed1991

A simple score and questionnaire to measure group changes in dietary fat intake.

BACKGROUND: A short 12-term questionnaire was designed to measure changes in the dietary intake of saturated and total fat among groups of people attending health promotion events. A simple score (the fat-habits score) derived from the questionnaire was compared with estimates of saturated and total fat intake (% total energy) estimated from a standard 180-item food frequency questionnaire of 105 children (less than 18 years) and 202 adults (greater than 18 years). RESULTS: The correlation coefficients for saturated fat intake and the fat-habits score were 0.60 (95% CI = 0.50 to 0.68) in adults and 0.54 (95% CI = 0.39 to 0.66) in children, and those for total fat and the fat-habits score were 0.46 (95% CI = 0.41 to 0.56) in adults and 0.40 (95% CI = 0.22 to 0.55) in children. Linear regression equations relating the fat-habits score to saturated and total fat were used to predict changes in fat intake in 12 children and 27 adults who completed both questionnaires 6 months apart. The differences between the predicted changes in saturated and total fat and the observed changes measured by the food frequency questionnaires were not significant (saturated fat: adults -0.3%, 95% CI = -1.3 to 0.7%; children -0.2%, 95% CI = -1.7 to 1.3%; total fat: adults -0.6%, 95% CI = -2.9 to 1.7%; children -0.4%, 95% CI = -2.8 to 2.0%). The study had a 90% power of detecting a difference between the predicted and the observed changes for saturated fat of greater than +/- 1.7% (adults) and +/- 2.5% (children), and for total fat of greater than +/- 3.9% (adults) and +/- 4.0% (children). Conclusion. Thus simple scores can be used to evaluate group changes in fat intake.

Adolescent↗
PubMed1991

Patterns of use of chest physiotherapy in a teaching hospital.

Studies of chest physiotherapy in medical patients have consistently shown benefit only in patients who produce large amounts of sputum. Among surgical patients systematically repeated maximal inspiration is the only procedure that clearly reduces the incidence of post-operative pulmonary complications. Rationalization of the use of physiotherapy requires data on the pattern of its use. To obtain such data an audit was conducted on the use of physiotherapy in patients discharged from Royal Newcastle Hospital in October 1989. It was suspected that respiratory physicians would account for the bulk of chest physiotherapy. All patients admitted under respiratory physicians and random samples of patients admitted under other physicians and under surgical specialists were surveyed. Chest physiotherapy was ordered in 13/44 (30%) patients cared for by respiratory physicians, 5/45 (11%) other medical patients and 11/48 (23%) surgical patients (P = 0.049). Chest physiotherapy was ordered in 28 of 29 instances for conditions in which it is of no proven benefit. From the total numbers of medical and surgical patients it was estimated that 71% of chest physiotherapy referrals in October 1989 were for non-medical patients. About half of all referrals were initiated by junior medical staff. Much of the chest physiotherapy performed in the hospital was unlikely to have been of major clinical value and patients with respiratory illnesses were minor consumers of chest physiotherapy. Attempts to reduce wasteful overuse of chest physiotherapy may be most effective if directed at physiotherapists. If medical staff are targeted it would be essential to reach those attached to surgical units.

Drainage, Postural↗
PubMed1990

Effectiveness and hazards of case finding for a high cholesterol concentration.

OBJECTIVE: To see whether adults with high blood cholesterol concentrations (greater than 6.5 mmol/l) detected by case finding return to their doctor, receive appropriate advice, and report changes in their diet and whether adults found not to have high cholesterol concentrations on case finding are discouraged from changing their diet. DESIGN: Follow up study. SETTING: Seven general practices in the lower Hunter region of Australia. PARTICIPANTS: 600 Men and women aged 25-65 who had their blood cholesterol concentrations measured three to four months earlier while attending their general practitioner. Analysis conducted on 552 (92%) who returned follow up postal questionnaires. MEASUREMENTS AND MAIN RESULTS: Of the 125 subjects found to have blood cholesterol concentrations greater than 6.5 mmol/l, 102 (82%) returned to their doctor and 83 of these recalled receiving dietary advice. 93 (75%) Subjects with high concentrations reported changing their diet compared with 72 (46%) subjects with concentrations of greater than 5.5-6.5 mmol/l and 44 (17%) subjects with lower concentrations. Overall 333 (61%) of all respondents who answered reported not changing their diet, the most common reason (nearly half the sample; n = 266) being that their cholesterol concentration was "all right." Adults without high cholesterol concentrations who returned to their doctor were also significantly more likely to recall their doctor saying that they did not need to lower their concentrations (less than or equal to 5.5 mmol/l = 61%; greater than 5.5-6.5 mmol/l = 12%; greater than 6.5 mmol/l = 5%) and significantly less likely to recall receiving dietary advice (less than or equal to 5.5 mmol/l = 13%; greater than 5.5-6.5 mmol/l = 60%; greater than 6.5 mmol/l = 82%). CONCLUSIONS: High risk strategies which require everyone to be tested for high cholesterol concentrations may interfere with population strategies designed to reduce everyone's dietary intake of fat.

Adult↗
PubMed1988

Comparison of Reflotron and laboratory cholesterol measurements.

Fifty-three patients from a general practice and 33 subjects who were in a community-screening promotion underwent total cholesterol level measurements both with a portable Reflotron system and by a standardized laboratory procedure. The intraclass correlation coefficient between the paired measurements was equal to 0.956; this suggests that the results of the Reflotron system agreed very closely with those of the laboratory procedure. In spite of this agreement, the Reflotron instrument, on average, gave lower results than did the laboratory procedure (mean difference, -0.164 mmol/L; 95% confidence interval, -0.094 to -0.234 mmol/L). This difference is small and, in comparison with other sources of variation in cholesterol measurement, is unlikely to be important in day-to-day clinical practice. However, the difference between the two methods appeared to be related to the cholesterol level (larger differences at lower cholesterol levels). In large studies, where small differences in cholesterol levels are important, this difference should be considered against the obvious convenience of rapid portable cholesterol measurements.

Adult↗
PubMed1988

High cholesterol levels: is mass screening the best option?

Individuals with a high cholesterol level (greater than 6.5 mmol/L) are at a relatively high risk of developing coronary heart disease in the future and an important part of any programme to prevent coronary heart disease is the identification and treatment of these individuals. Mass screening can identify those who are at an increased risk but the likely benefits and costs of such a programme have not been assessed adequately. Before such a method is promoted, we need to know: how well it detects high-risk individuals (yield); what reductions in the risk of coronary heart disease can be expected in those who are screened as "positive"; what adverse effects screening may have on those who are screened as "negative"; and what the logistics and costs (both to those who are screened and to the community as a whole) are. Until we know this information the urge to promote mass screening for cholesterol levels should be restrained, and only those who are at high risk of coronary heart disease should be selected for the determination of their cholesterol levels.

Adult↗