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Biomedical subjects

S MacMahon

Publications and source records attributed to S MacMahon.

At least 19 recordsLinked to original sources
PubMed1997

Socioeconomic distribution of smoking in a population of 10,529 New Zealanders.

AIMS: This study aimed to investigate the associations of several smoking variables with socioeconomic status. METHODS: Cross-sectional analyses of data about smoking behaviour and socioeconomic status (education, occupation and neighbourhood income) were performed using baseline data from the Fletcher Challenge-University of Auckland Heart and Health Study (10,529 participants). RESULTS: After adjustment for age and sex, lower educational level was associated with: (1) higher frequency of ever having smoked (65% of participants who had attended secondary school for fewer than two years, versus 43% of participants who had attended university; 2p < 0.0001); (2) lower likelihood of having quit (46% versus 71%; 2p < 0.0001); (3) higher likelihood of being a current smoker (35% versus 12%; 2p < 0.0001); (4) higher tobacco consumption per smoker (13 manufactured cigarettes/day versus 8 manufactured cigarettes/day; 2p < 0.0001); and (5) higher tobacco consumption per participant (1980 cigarette-equivalents/year versus 450 cigarette-equivalents/year; 2p < 0.0001). Similar, but shallower, associations of these smoking variables were observed with occupation and neighbourhood income (with the exception that tobacco consumption per smoker was not associated with neighbourhood income). The socioeconomic gradients of tobacco consumption per study participant with all three socioeconomic indicators were particularly steep among younger participants, men and Maori. CONCLUSIONS: Participants of low socioeconomic status consumed a disproportionately large amount of tobacco. Policies that prevent smoking initiation and promote smoking cessation in low socioeconomic groups are therefore needed. These should include targeting of mass media messages to low socioeconomic groups, public subsidisation of nicotine replacement therapy and higher taxes on tobacco.

Adult↗
PubMed1997

Regional variation in the incidence of hip fracture in New Zealand.

AIM: To determine the regional incidence of hip fracture among individuals aged 60 years or older in New Zealand. METHODS: New Zealand Health Information Service inpatient morbidity data for the years 1988-92 were examined by area health board region to identify all hip fractures (ICD N820) among individuals aged 60 years or older. RESULTS: Substantial regional variation exists in the incidence of hip fractures among older people in New Zealand. Among both men and women, similar regional variations were observed with the age-standardised rates being consistently highest in the West Coast (790 per 100,000 for women and 360 per 100,000 in men) and lowest in Northland (540 per 100,000 in women and 185 per 100,000 in men). CONCLUSION: These findings have implications for resource allocation, both in terms of targeting prevention initiatives and in providing acute and long term management of hip fracture patients. In addition, they raise questions as to why such variations in hip fracture incidence exist in New Zealand.

Aged↗
PubMed1997

Migraine: a risk factor for motor vehicle driver injury?

To test the hypothesis that migraine is associated with motor vehicle driver injury, data collected from 10,529 individuals on personal history of migraine and motor vehicle injury were analysed cross-sectionally. In multiple logistic regression analyses, the adjusted odds ratio for motor vehicle driver injury associated with migraine was 2.3 [95% confidence interval (CI) 1.9-2.7]. After excluding those who also had a history of head injury, the odds ratio was 1.5 (95% CI: 1.2-2.0). These results suggest that migraine may be associated with a 50% increase in the risk of motor vehicle driver injury and that in this population may account for as many as one in every 20 motor vehicle driver injuries. These findings require confirmation in prospective studies of motor vehicle driver injuries.

Accidents, Traffic↗
PubMed1997

Left ventricular remodeling with carvedilol in patients with congestive heart failure due to ischemic heart disease. Australia-New Zealand Heart Failure Research Collaborative Group.

OBJECTIVES: The aim of this study, a substudy of the Australia-New Zealand trial of carvedilol in patients with heart failure due to ischemic heart disease, was to determine the effects of this treatment on left ventricular size and function with the use of quantitative two-dimensional (2D) echocardiography. BACKGROUND: Beta-adrenergic blocking drugs have been shown to improve left ventricular ejection fraction in patients with heart failure due to either ischemic heart disease or idiopathic dilated cardiomyopathy. However, the effects of such treatment on left ventricular size remain uncertain. METHODS: One hundred twenty-three patients from 10 centers in New Zealand and Australia participated in the 2D echocardiographic substudy. Echocardiography was performed before randomization and was repeated after 6 and 12 months of treatment. Left ventricular end-diastolic and end-systolic volumes were measured from apical four- and two-chamber views with the use of a modified Simpson's rule method. RESULTS: After 12 months, heart rate was 8 beats/min lower in the carvedilol than in the placebo group, whereas left ventricular end-diastolic and end-systolic volumes were increased in the placebo group but reduced in the carvedilol group. At 12 months, left ventricular end-diastolic volume index was 14 ml/m2 less in the carvedilol than in the placebo group (p = 0.0015); left ventricular end-systolic volume index was 15.3 ml/m2 less (p = 0.0001), and left ventricular ejection fraction was 5.8% greater (p = 0.0015). CONCLUSIONS: In patients with heart failure due to ischemic heart disease, carvedilol therapy for 12 months reduced left ventricular volumes, increased left ventricular ejection fraction and prevented progressive left ventricular dilation. These changes demonstrate a beneficial effect of carvedilol on left ventricular remodeling in heart failure. The observed changes may explain in part the improved clinical outcomes produced by treatment with carvedilol.

Adrenergic beta-Antagonists↗
PubMed1997

Effect of treatment with simvastatin on serum cholesteryl ester transfer in patients on dialysis. PERFECT Study Collaborative Group.

BACKGROUND: Plasma cholesteryl ester transfer activity is increased in patients with chronic renal failure on dialysis who have elevated levels of apolipoprotein B (apoB)-containing lipoproteins. Simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitor, reduces levels of these lipoproteins but the effect of treatment on cholesteryl ester transfer activity in patients on dialysis remains to be determined. METHODS: We measured serum newly synthesized cholesteryl ester transfer (NCET) activity, lecithin:cholesterol acyltransferase (LCAT) activity and serum lipid, lipoprotein and apolipoprotein concentrations before and immediately after 6 months treatment with simvastatin (10 mg daily, n = 24) or placebo (n = 29) in 53 patients with chronic renal failure receiving haemodialysis or continuous ambulatory peritoneal dialysis (CAPD). RESULTS: Simvastatin therapy significantly reduced serum cholesterol, LDL cholesterol, apoB concentrations, and both NCET (P = 0.001) and LCAT (P = 0.012) rates. The decrease in NCET activity was correlated significantly with the corresponding decrease in apoB concentration (r = 0.715, P < 0.001) and LCAT activity (r = 0.715, P < 0.001) during simvastatin therapy and was no longer significant when apoB concentration (P = 0.14) or LCAT activity (P = 0.07) were controlled. CONCLUSIONS: These data show that simvastatin therapy reduces serum NCET rates, and suggest that this may be linked to the concomitant decrease in levels of apoB-containing lipoproteins which are acceptors of transferred cholesteryl esters, and to the decrease in serum LCAT rates in patients with chronic renal failure with treatment.

Adolescent↗
PubMed1997

Effects of beta-blocker therapy on mortality in patients with heart failure. A systematic overview of randomized controlled trials.

AIMS: Several randomized trials have reported that beta-blocker therapy improves left ventricular function and reduces the rate of hospitalization in patients with congestive heart failure. However, most trials were individually too small to assess reliably the effects of treatment on mortality. In these circumstances a systematic overview of all trials of beta-blocker therapy in patients with congestive heart failure may provide the most reliable guide to treatment effects. METHODS AND RESULTS: Details were sought from all completed randomized trials of oral beta-blocker therapy in patients with heart failure of any aetiology. In particular, data on mortality were sought from all randomized patients for the scheduled treatment period. The typical effect of treatment on mortality was estimated from an overview in which the results of all individual trials were combined using standard statistical methods. Twenty-four randomized trials, involving 3141 patients with stable congestive heart failure were identified. Complete data on mortality were obtained from all studies, and a total of 297 deaths were documented during an average of 13 months of follow-up. Overall, there was a 31% reduction in the odds of death among patients assigned a beta-blocker (95% confidence interval 11 to 46%, 2P = 0.0035), representing an absolute reduction in mean annual mortality from 9.7% to 7.5%. The effects on mortality of vasodilating beta-blockers (47% reduction SD 15), principally carvedilol, were non-significantly greater (2P = 0.09) than those of standard agents (18% reduction SD 15), principally metoprolol. CONCLUSIONS: Beta-blocker therapy is likely to reduce mortality in patients with heart failure. However, large-scale, long-term randomized trials are still required to confirm and quantify more precisely the benefit suggested by this overview.

Administration, Oral↗
PubMed1996

Ethnic differences in blood pressure: findings from the Fletcher Challenge-Auckland University Heart and Health Study.

AIMS: To investigate the determinants of ethnic differences in blood pressure, hypertension and the prevalence of additional risk factors for cardiovascular disease among a New Zealand population. METHODS: Baseline data from the Fletcher Challenge-University of Auckland Heart and Health Study were analysed for ethnic differences in blood pressure, and the likelihood of those with hypertension having other major cardiovascular disease risk factors was estimated. RESULTS: Maori and Pacific Islands participants had mean diastolic blood pressure up to 3 mmHg higher than Europeans, but Pacific Islands people had mean systolic blood pressure 3-4 mmHg lower than Europeans and Maori respectively. After adjustment for age and gender almost 20% of Maori, 16% of Pacific Islands and 11% of European people were classified as hypertensive. Adjustment for body mass index and alcohol consumption almost eliminated ethnic differences in blood pressure, and body mass index was found to be the single most important modifiable determinant of raised blood pressure. Greater proportions of Maori (15%) and Pacific Islands people (14%) with hypertension had multiple additional cardiovascular risk factors compared with Europeans (8%), but similar proportions were on antihypertensive drug treatment. CONCLUSIONS: Efforts to reduce obesity have the potential to significantly reduce raised blood pressure among Maori and Pacific Islands people. Overall cardiovascular risk is more likely to be higher in Maori and Pacific Islands people than in Europeans with hypertension, indicating that greater proportions of Maori and Pacific Islands people with high blood pressure should be receiving treatment.

Adult↗
PubMed1996

Forty years of randomised trials in the New Zealand Medical Journal.

AIM: To identify all randomised trials published in the New Zealand Medical Journal, to document the basic characteristics of these trials and to count the number that were detectable on medline. METHODS: All issues of the New Zealand Medical Journal between 1943 and 1995 were systematically hand-searched. All trials identified were characterised and compared against the trials identified using an optimal medline search strategy. RESULTS: The handsearch identified 152 randomised controlled trials, the first published in 1955. Half the trials recruited less than 34 participants and more than 90% were of pharmaceutical interventions. Only 18% of studies reported on the method of randomisation and 13% provided evidence that final analyses were conducted on an intention to treat basis. Fifty one percent of trials employed a placebo control group and 28% involved a crossover design. Since 1966, when Medline became available, 143 trials were published of which 89 (62%) were identified by the Medline search. CONCLUSIONS: Two of the major difficulties that face those preparing systematic reviews were illustrated by this survey. First, important information on design and analysis is often missing from reports of trials. Second, a large proportion of published randomised trials are not identifiable on Medline. Standard formats for reporting the results of trials and inclusion of trials identified by hand-searching on the Cochrane Collaboration's International Register of Randomised Controlled Trials of Health Care will facilitate the future production of reliable systematic reviews.

Data Interpretation, Statistical↗
PubMed1996

Clinical effects of anticoagulant therapy in suspected acute myocardial infarction: systematic overview of randomised trials.

OBJECTIVES: Most randomised trials of anticoagulant therapy for suspected acute myocardial infarction have been small and, in some, aspirin and fibrinolytic therapy were not used routinely. A systematic overview (meta-analysis) of their results is needed, in particular to assess the clinical effects of adding heparin to aspirin. DESIGN: Computer aided searches, scrutiny of reference lists, and inquiry of investigators and companies were used to identify potentially eligible studies. On central review, 26 studies were found to involve unconfounded randomised comparisons of anticoagulant therapy versus control in suspected acute myocardial infarction. Additional information on study design and outcome was sought by correspondence with study investigators. SUBJECTS: Patients with suspected acute myocardial infarction. INTERVENTIONS: No routine aspirin was used among about 5000 patients in 21 trials (including half of one small trial) that assessed heparin alone or heparin plus oral anticoagulants, and aspirin was used routinely among 68,000 patients in six trials (including the other half of one small trial) that assessed the addition of intravenous or high dose subcutaneous heparin. MAIN OUTCOME MEASUREMENTS: Death, reinfarction, stroke, pulmonary embolism, and major bleeds (average follow up of about 10 days). RESULTS: In the absence of aspirin, anticoagulant therapy reduced mortality by 25% (SD 8%; 95% confidence interval 10% to 38%; 2P = 0.002), representing 35 (11) fewer deaths per 1000. There were also 10 (4) fewer strokes per 1000 (2P = 0.01), 19 (5) fewer pulmonary emboli per 1000 (2P < 0.001), and non-significantly fewer reinfarctions, with about 13 (5) extra major bleeds per 1000 (2P = 0.01). Similar sized effects were seen with the different anticoagulant regimens studied. In the presence of aspirin, however, heparin reduced mortality by only 6% (SD 3%; 0% to 10%; 2P = 0.03), representing just 5 (2) fewer deaths per 1000. There were 3 (1.3) fewer reinfarctions per 1000 (2P = 0.04) and 1 (0.5) fewer pulmonary emboli per 1000 (2P = 0.01), but there was a small non-significant excess of stroke and a definite excess of 3 (1) major bleeds per 1000 (2P < 0.0001). CONCLUSIONS: The clinical evidence from randomised trials dose not justify the routine addition of either intravenous or subcutaneous heparin to aspirin in the treatment of acute myocardial infarction (irrespective of whether any type of fibrinolytic therapy is used).

Anticoagulants↗
PubMed1996

Blood pressure lowering in patients with cerebrovascular disease: results of the PROGRESS (Perindopril Protection Against Recurrent Stroke Study) pilot phase.

1. Among patients with cerebrovascular disease, there is a direct and continuous association between blood pressure and the risk of stroke, but previous trials of blood pressure lowering in this patient group have been inconclusive. 2. PROGRESS (Perindopril Protection Against Recurrent Stroke Study) is a multicentre, randomized, placebo-controlled trial that aims to determine reliably the effect of angiotensin converting enzyme (ACE) inhibitor-based blood pressure lowering on stroke risk in patients with a history of cerebrovascular disease. If a 4 week run-in period on active perindopril is well tolerated, participants are randomized to either perindopril (4 mg) +/- indapamide (2.5 mg) or matching placebo(s). The primary study outcome is stroke and follow-up is for a minimum of 4 years. 3. For the pilot study nearly 5000 medical records were screened and 60 patients with recent cerebrovascular events were approached directly in hospital or at a clinic visit. Sixty-seven patients entered the run-in phase (52 from retrospective screening and 15 by prospective approach) and 60 patients proceeded to randomization. Treatment with perindopril was well tolerated; only three patients were withdrawn due to side effects and four were withdrawn for other reasons. The mean age of randomized patients was 68 years; 70% were male and 55% were 'non-hypertensive'. The mean entry blood pressure was 142/83 mmHg and following pre-randomization treatment this was reduced by 7/4 mmHg. 4. Most patients were identified by retrospective review of medical records, but this was less efficient than prospective methods. Blood pressure lowering was well tolerated by both hypertensive and non-hypertensive patients with cerebrovascular disease. The small numbers of patients and the non-randomized nature of the data reported limit the conclusions that can be drawn, but the results confirm the feasibility of the main study.

Antihypertensive Agents↗
PubMed1996

Attitudes and practices of New Zealand anaesthetists with regard to epidural and subarachnoid anaesthesia.

A survey was conducted among 259 New Zealand specialist anaesthetists to assess attitudes and practices with regard to epidural or subarachnoid anaesthesia (ESA). Ninety-four per cent replied and virtually all of the respondents indicated that they performed ESA at some time. ESA was used by most anaesthetists for most patients undergoing major hip or knee surgery, abdomino-perineal resection, cystectomy, caesarean section or transurethral resection of the prostate, ESA was used is about half of patients undergoing abdominal aortic aneurysm repair, femoro-popliteal bypass or thoracotomy and there was marked variation between anaesthetists in the frequency of using ESA for these procedures. There was broad consensus about the importance of a number of factors that might influence the decision to employ ESA; in particular that systemic sepsis and prolonged bleeding time were important contraindications and that patient preference and chronic lung disease were important indications. However respondents were equally divided as to whether they felt that recent myocardial infarction or congestive heart failure constituted indications or contraindications to ESA.

Anesthesia, Epidural↗