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Biomedical subjects

K McPherson

Publications and source records attributed to K McPherson.

At least 73 records · Page 4Linked to original sources
PubMed1998

Mortality in vegetarians and non-vegetarians: a collaborative analysis of 8300 deaths among 76,000 men and women in five prospective studies.

OBJECTIVE: To compare the mortality rates of vegetarians and non-vegetarians. DESIGN: Collaborative analysis using original data from five prospective studies. Death rate ratios for vegetarians compared to non-vegetarians were calculated for ischaemic heart disease, cerebrovascular disease, cancers of the stomach, large bowel, lung, breast and prostate, and for all causes of death. All results were adjusted for age, sex and smoking. A random effects model was used to calculate pooled estimates of effect for all studies combined. SETTING: USA, UK and Germany. SUBJECTS: 76,172 men and women aged 16-89 years at recruitment. Vegetarians were those who did not eat any meat or fish (n = 27,808). Non-vegetarians were from a similar background to the vegetarians within each study. RESULTS: After a mean of 10.6 years of follow-up there were 8330 deaths before the age of 90 years, including 2264 deaths from ischaemic heart disease. In comparison with non-vegetarians, vegetarians had a 24% reduction in mortality from ischaemic heart disease (death rate ratio 0.76, 95% CI 0.62-0.94). The reduction in mortality among vegetarians varied significantly with age at death: rate ratios for vegetarians compared to non-vegetarians were 0.55 (95% CI 0.35-0.85), 0.69 (95% CI 0.53-0.90) and 0.92 (95% CI 0.73-1.16) for deaths from ischaemic heart disease at ages <65, 65-79 and 80-89 years, respectively. When the non-vegetarians were divided into regular meat eaters (who ate meat at least once a week) and semi-vegetarians (who ate fish only or ate meat less than once a week), the ischaemic heart disease death rate ratios compared to regular meat eaters were 0.78 (95% CI 0.68-0.89) in semi-vegetarians and 0.66 (95% CI 0.53-0.83) in vegetarians (test for trend P< 0.001). There were no significant differences between vegetarians and non-vegetarians in mortality from the other causes of death examined. CONCLUSION: Vegetarians have a lower risk of dying from ischaemic heart disease than non-vegetarians.

Adolescent↗
PubMed1997

Impact of postmenopausal hormone therapy on cardiovascular events and cancer: pooled data from clinical trials.

OBJECTIVE: To examine the incidence of cardiovascular diseases and cancer from published clinical trials that studied other outcomes of postmenopausal hormone therapy as some surveys have suggested that it may decrease the incidence of cardiovascular diseases and increase the incidence of hormone dependent cancers. DESIGN: Trials that compared hormone therapy with placebo, no therapy, or vitamins and minerals in comparable groups of postmenopausal women and reported cardiovascular or cancer outcomes were searched from the literature. SUBJECTS: 22 trials with 4124 women were identified. In each group, the numbers of women with cardiovascular and cancer events were summed and divided by the numbers of women originally allocated to the groups. RESULTS: Data on cardiovascular events and cancer were usually given incidentally, either as a reason for dropping out of a study or in a list of adverse effects. The calculated odds ratios for women taking hormones versus those not taking hormones was 1.39 (95% confidence interval 0.48 to 3.95) for cardiovascular events without pulmonary embolus and deep vein thrombosis and 1.64 (0.55 to 4.18) with them. It is unlikely that such results would have occurred if the true odds ratio were 0.7 or less. For cancers, the numbers of reported events were too low for a useful conclusion. CONCLUSIONS: The results of these pooled data do not support the notion that postmenopausal hormone therapy prevents cardiovascular events.

Cardiovascular Diseases↗
PubMed1997

Mortality among appropriately referred patients refused admission to intensive-care units.

BACKGROUND: The provision of intensive care is a perplexing issue for clinicians and the public. Concerns about the apparent lack of beds and the appropriateness of the patients admitted are tempered by the high cost of providing this service. As part of a study commissioned by the UK Department of Health, we tested the hypothesis that there is excess mortality among patients who are refused admission to intensive-care units. METHODS: All referrals to six intensive-care units with different numbers of beds were monitored during a 3-month period. Data on mortality 90 days after first referral were obtained from family physicians for all patients known to be alive at hospital discharge. We adjusted, where possible, for confounding, including for age, sex, appropriateness of referral, disease severity, surgery and emergency categories, and bed provision. We did multivariate analysis by multiple logistic regression to compare the adjusted 90-day mortality rates for patients who were refused admission and for those admitted. FINDINGS: 480 patients were admitted and 165 were refused admission. 90 days after referral there had been 178 (37%) deaths among the admitted group and 75 (46%) among the refused group. After multivariate adjustment, 113 patients appropriately referred for intensive care but refused admission to their first-choice intensive-care unit had a relative risk of death of 1.6 (95% CI 1.0-2.5), compared with the group of appropriately admitted cases with medium APACHE II scores for disease severity. Age, the assessed need for treatment or monitoring interventions, and emergency status also contributed to differences in mortality among all referrals. Bed provision did not contribute significantly to excess mortality. INTERPRETATION: Although this study is observational and case-mix adjustment is incomplete, we found a higher rate of attributable mortality in patients who were refused intensive care, particularly for emergency cases. We question whether the provision of more beds alone would be a solution and conclude that there is an urgent need for more appropriate admission and discharge criteria.

APACHE↗
PubMed1997

Medical Research Council randomised trial of endometrial resection versus hysterectomy in management of menorrhagia.

BACKGROUND: The most frequent indication for hysterectomy is menorrhagia, even though the uterus is normal in a large number of patients. Transcervical resection of the endometrium (TCRE) is a less drastic alternative, but success rates have varied and menorrhagia can recur. We have tested the hypothesis that the difference in the proportion of women dissatisfied and requiring further surgery within 3 years of TCRE or hysterectomy would be no more than 15%. METHODS: 202 women with symptomatic menorrhagia were recruited to a multicentre, randomised, controlled trial to compare the two interventions. TCRE and hysterectomy were randomly assigned in a ratio of two to one. The primary endpoints were women's satisfaction and need for further surgery. The patients' psychological and social states were monitored before surgery, then annually with a questionnaire. Analysis was by intention to treat. FINDINGS: Data were available for 172 women (56 hysterectomy, 116 TCRE); 26 withdrew before surgery and four were lost to follow-up. Satisfaction scores were higher for hysterectomy than for TCRE throughout follow-up (median 2 years), but the differences were not significant (at 3 years 27 [96%] of 28 in hysterectomy group vs 46 [85%] of 54 in TCRE group were satisfied; p = 0.16). 25 (22%) women in the TCRE group and five (9%) in the hysterectomy group required further surgery (relative risk 0.46 [95% CI 0.2-1.1], p = 0.053). TCRE had the benefits of shorter operating time, fewer complications, and faster rates of recovery. INTERPRETATION: TCRE is an acceptable alternative to hysterectomy in the treatment of menorrhagia for many women with no other serious disorders.

Adult↗
PubMed1997

Technical complications of endovascular abdominal aortic aneurysm repair.

PURPOSE: Results from 34 endovascular repairs of abdominal aortic aneurysms are reviewed to identify technical complications and relate them to anatomic and technical features of the operation. METHODS: Twenty-one patients underwent attempted tube graft repair (mean follow-up, 13 months). Thirteen patients underwent placement of a bifurcated graft (mean follow-up, 7.2 months). RESULTS: Twenty-five patients (74%) underwent repair without technical complication (16 tube graft and nine bifurcated graft). Of five patients who had tube graft complications, two involved small iliac arteries and resulted in arterial injury. One of these patients needed a femorofemoral bypass procedure, and the other required conversion to standard operation. Two patients had distal leaks associated with the attachment system, and one patient had misplacement of the distal attachment system. The two patients who had leaks were followed-up; one required operation after 7 months, whereas the other leak sealed. The patient who had distal attachment system misplacement had a second endograft placed within the first to provide a distal seal. The four patients who had bifurcated graft complications involved two graft limb stenoses, one managed with a Palmaz stent and the other with balloon angioplasty. The patient treated with balloon angioplasty had graft thrombosis 1 week after the operation, which resulted in the need for a femorofemoral bypass procedure. Another bifurcated graft patient had a graft limb twist, which has resulted in chronic claudication. One patient had placement of a limb too proximal in the common iliac artery with chronic leak, and an open operation was performed 18 months later. CONCLUSIONS: Technical complications in this series seem to be associated with short distal necks, small iliac arteries, tortuous iliac arteries, and atherosclerosis at the aortic bifurcation. We believe that experience and understanding of these issues will reduce the risk of these complications in the future.

Aged↗
PubMed1997

Modelling the effects of increased physical activity on coronary heart disease in England and Wales.

OBJECTIVE: To investigate the use of computer models as tools for policy makers in evaluating physical activity interventions aimed at reducing deaths from coronary heart disease (CHD). DESIGN: The cell-based computer model Prevent, adapted to simulate risk factor interventions for an English and Welsh population, was used to simulate the effect of two strategies for increasing physical activity levels in respect of CHD mortality over 25 years. The first strategy involved a 25% increase in the proportion of 15-64 year olds who were moderately active, while the second strategy involved a similar increase in the proportion who were vigorously active. The effects of focusing on narrower age ranges and on people at different initial activity levels were also explored. MAIN RESULTS: The simulations showed a small reduction in the CHD death rates--less than 0.15% and 0.06% for men and women respectively. The strategies would postpone up to 12,100 deaths over 25 years, comparable to the effect of a 2% reduction in smoking prevalence. The strategies seemed as if they would be more effective if they concentrated on men rather than women, on those over 45 years of age as opposed to all or younger age groups, and on the least active members of the population rather than those already taking some exercise. CONCLUSION: The use of computer modelling for stimulating physical activity strategies has shown that concentrating these interventions on older sedentary men will produce the greatest health gain, but efforts to encourage smoking cessation may be more effective in terms of years of life saved.

Adolescent↗
PubMed1997

Why do women doctors in the UK take hormone replacement therapy?

STUDY OBJECTIVES: To ascertain the determinants and experiences of hormone replacement therapy (HRT) use by menopausal women doctors. DESIGN: Postal questionnaire. SETTING: UK. PATIENTS: A randomized stratified sample of women doctors who obtained full registration between 1952 and 1976, taken from the current Principal List of the UK Medical Register. MAIN OUTCOME MEASURES: Current and previous use of HRT; reasons for and against HRT use; menopausal status; hormonal contraceptive use; lifestyle patterns; family and personal history of disease. MAIN RESULTS: While 73.2% of 471 users had started HRT for symptom relief, 60.9% cited prevention of osteoporosis and 32.7 prevention of cardiovascular disease. Altogether 18.7% had started for preventive purposes alone. Significant predisposing factors to starting HRT were the presence and severity of menopausal symptoms, surgical menopause, past use of hormonal contraception, and a family history of osteoporosis. HRT users were also more likely to use skimmed rather than full fat milk, to try to increase their intake of fruit, vegetables, and fibre, and to undertake vigorous physical activity at least once a week. They were less likely to have had breast cancer. Long duration users were more likely than short duration users to be past users of hormonal contraception and to be using HRT for prevention of osteoporosis as well as symptom relief; they were less likely to have experienced side effects. CONCLUSIONS: The high usage of HRT by women doctors reflects the fact that many started HRT on their own initiative and with long term prevention in mind. The results may become generalisable to the wider population as information on the potential benefits of HRT is disseminated and understood. However, HRT users may differ slightly from non-users in health-related behaviour and a substantial minority may never take up HRT, at least until the benefit-risk ratio is more clearly established.

Attitude of Health Personnel↗
PubMed1997

Are randomized controlled trials controlled? Patient preferences and unblind trials.

The most reliable information about treatment effects comes from randomized controlled trials (RCTs). However, the possibility of subtle interactions--for example, between treatment preferences and treatment effects--is generally subordinated in the quest for evidence about main treatment effects. If patient preferences can influence the effectiveness of treatments through poorly understood (psychological) pathways, then RCTs, particularly when unblinded, may wrongly attribute effects solely to a treatment's physiological/pharmacological properties. To interpret the RCT evidence base it is important to know whether any preference effects exist and, if so, by how much they affect outcome. Reliable measurement of these effects is difficult and will require new approaches to the conduct of trials. In view of the fanciful image with which such effects are portrayed and the uncertainties about their true nature and biological mechanisms, existing evidence is unlikely to provide sufficient justification for investment in trials. This is a Catch 22. Until an escape is found we might never know, even approximately, how much of modern medicine is attributable to psychological processes.

Humans↗
PubMed1997

Pain levels after total hip replacement: their use as endpoints for survival analysis.

We have assessed the relative value of various outcome measures after THR, by the analysis of follow-up data from over 2000 patients. They had been reviewed clinically and radiologically six months after operation, at one year, and then every two years, some for 16 years. At each review their pain level, stiffness and opinion of progress were scored and a radiograph taken. We found that pain level was the most informative outcome as a predictor of revision and correlated well with the patients' opinions. We made a comparison between the six types of implant in the series, using survival analysis and log-rank testing with different pain levels as endpoints. This analysis revealed differences which were not detected by survival analysis using the traditional endpoint of revision. We therefore recommend the use of different levels of pain as the main outcome measures after total hip replacement.

Adolescent↗