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Biomedical subjects

L McKenzie

Publications and source records attributed to L McKenzie.

At least 37 records · Page 2Linked to original sources
PubMed1993

Variation in cesarean section rates among hospitals in Washington State.

OBJECTIVES: This study examined hospital characteristics and hospital population risk factors and their associations with hospital-specific cesarean section rates in Washington State. METHODS: Data were obtained from 1987 birth certificates. The study population included all hospitals that had 12 or more singleton live births. RESULTS: Hospital-specific cesarean section rates varied from 0% to 43% and were positively associated with proprietary ownership, size of delivery service, and the proportions of women who had complications or high-birthweight infants. The proportion of women who had late prenatal care was inversely associated with cesarean section rates. Although proprietary hospitals had higher cesarean section rates, their patient populations were lower risk than patients of public or teaching hospitals. CONCLUSIONS: Variation in cesarean section rates among hospitals cannot be fully explained by either hospital or patient population characteristics. A combined strategy may be necessary to lower unjustifiably high cesarean section rates.

Adolescent↗
PubMed1993

Management ethics for the health care supervisor.

Someone once described the difference between ethical and unethical behavior in these terms: After doing something ethical you feel good; after doing something unethical you feel bad. Not quite. Feelings have something to do with ethics but not everything. Feelings may legitimately play into the moral reasoning associated with senses of guilt and guiltlessness, but moral reasoning demands critical thinking if it is to be honest. The ability to think critically on moral issues, it is argued here, is a competence that must be exercised by all professionals.

Confidentiality↗
PubMed1992

Using decision analysis to calculate the optimum treatment for microinvasive cervical cancer.

Decision theory was used to calculate the optimum treatment of microscopic squamous cervical cancer using probabilities obtained from an exhaustive literature review and a range of plausible value estimates. This showed that if there is no vascular involvement, survival is maximised by conservative treatment if tumour invasion is less than 3 mm while treatment by radical surgery results in maximal survival rates if the tumour invasion is over 3 mm. Radical surgery also maximises survival for smaller lesions where lymph channel involvement is present, especially if a surgical mortality at the lower end of the reported range is assumed. Refinement of our analysis to include an assessment of patient values showed that these conclusions are still valid regardless of the patient's relative preference for death from surgery or death from cancer. However, the wish to preserve fertility sharply reduces the overall net benefit of surgery. Conservative treatment becomes the preferred option for all microinvasive lesions even for patients who are prepared to trade-off a small (e.g. 2%) risk of death in order to retain their fertility.

Adult↗
PubMed1992

Familial Scheuermann disease: a genetic and linkage study.

Scheuermann juvenile kyphosis or Scheuermann disease is the most frequent cause of kyphosis in adolescence. However, the natural history and genetic basis is still unknown. Reports of identical radiological changes in monozygotic twins, sib recurrence, and transmission over three generations suggest underlying heritability. In this study, 12 probands were referred to us. Upon radiological examination of the proband's parents and sibs, seven were shown to have familial Scheuermann disease with an autosomal dominant pattern of inheritance. Of the remaining five probands, four had chromosomal anomalies. The three largest pedigrees were subjected to linkage analysis with three candidate genes: Duffy, COL1A1, and COL1A2. Linkage of Scheuermann disease was excluded with Duffy (lod score = -2.195 at theta = 0.10) and COL1A2 (lod score = -2.750 at theta = 0.05) in these families.

Adolescent↗
PubMed1992

Critical thinking in health care supervision.

Henry Ford is reputed to have said that thinking is the hardest work there is, which is probably why so few people engage in it. Perhaps many people have felt this way sometimes, especially when they viewed the foibles of the human race displayed prominently on the evening television news. Some people do stupid things; some people seem to be mindless in what they do. This applies also to some in managerial and supervisory positions in health care organizations. The percentage of these thoughtless managers and supervisors is probably comparable to the percentage of the thoughtless people in the general population. Fortunately every normal functioning human being is capable of becoming a more critical thinker. Of course, no amount of effort is adequate to the development of critical thinking when a person lacks fundamental good sense. On the other hand, no amount of genius suffices when someone does not put forth adequate effort to become a more critical thinker.

Decision Making, Organizational↗
PubMed1991

Estrogen therapy and variable-resistance weight training increase bone mineral in surgically menopausal women.

This study was undertaken to examine the effect of estrogen replacement therapy alone and estrogen replacement therapy plus variable-resistance weight training on the bone mineral content of surgically menopausal women. A total of 20 surgically menopausal women were randomized and treated with either 0.625 mg conjugated estrogen daily or the same dose of estrogen plus a closely monitored exercise program involving the use of Nautilus muscle strengthening/endurance equipment. After 1 year's observation, the bone mineral density (BMD) of the spine determined by dual-photon absorptiometry increased in the exercising subjects by 8.3 +/- 5.3% (p = 0.004), 95% confidence limits (CL) 3.9-12.8%; the group with estrogen replacement therapy alone maintained their BMD: 1.5 +/- 12.4% (p = 0.36; 95% CL = -6.9-9.8%). The total body BMD of the exercising group increased by 2.1 +/- 1.5% (p = 0.003; 95% CL = 0.8-3.3%); the nonexercising women had a nonsignificant 0.6 +/- 2.9% change (p = 0.30; 95% CL = -1.4-2.5%). A significant increase of 4.1 +/- 4.3% (p = 0.01; 95% CL = 0.8-7.4%) in the radial midshaft BMD of the exercising group was found; the estrogen alone group recorded a nonsignificant change of -0.3 +/- 3.1% (p = 0.33; 95% CL = -1.7-2.4%). The results of this study suggest that variable-resistance training in estrogen-replete women adds bone to both the axial and appendicular skeleton.

Absorptiometry, Photon↗
PubMed1991

The effect of low-dose oral contraceptives on lipids and lipoproteins in two at-risk populations: young female smokers and older premenopausal women.

Young women who smoke and women over age 35 are considered to be at high risk for cardiovascular complications associated with oral contraceptive use. This study evaluated the effects of low-dose oral contraceptives on lipid and lipoprotein concentrations in 45 high-risk patients before, during, and after 6 months of treatment. Neither group showed a significant change from baseline in cholesterol, HDL cholesterol, LDL cholesterol or cholesterol ratios. Triglycerides increased and HDL2a levels decreased significantly in both groups but returned to baseline after treatment was discontinued, with the largest changes in both triglycerides and HDL2a levels occurring at 1 month. The change in triglyceride and HDL2a blood levels were within the laboratories' reference range. The lipid profile of these patients, therefore, was not worsened significantly through 6 months of oral contraceptive use. The young women who smoked did have consistently lowered levels of HDL cholesterol and its HDL2a subfraction when compared to their elder non-smoking cohort.

Adult↗
PubMed1990

Ablation of endometriotic implants in rabbits by hematoporphyrin derivative photoradiation therapy using the gold vapor laser.

In a rabbit model, endometriotic lesions were utilized to study hematoporphyrin derivative (HPD) uptake and the effect of photoradiation using the gold vapor laser. Morphological studies confirmed successful induction of ectopic endometrial growth and the lesions displayed preferential HPD uptake compared to normal intraperitoneal structures. Gold vapor laser irradiation of the lesions in HPD pretreated animals produced necrosis of the endometriotic lesions leaving surrounding tissues healthy. Results from this study suggest that HPD-mediated photodynamic therapy may be a suitable means of treating endometriosis in the human.

Animals↗
PubMed1990

Mobile breast screening: factors affecting uptake, efforts to increase response and acceptability.

In 1986, a breast screening project was set up to assess the feasibility of mobile breast screening in rural areas near Edinburgh. Secondary objectives included a study of factors affecting uptake, ways in which uptake might be encouraged and a study of the acceptability of this form of screening. This paper deals with the results of studies dealing with secondary objectives. We found that response rates to opportunistic screening was poor, 5,631 attenders out of 23,229 eligible women (24.2%). This was especially so in older women. Distance proved to be the single most significant factor affecting uptake, but car and house ownership were also highly significantly correlated with response. Leaflet drops had no demonstrable effect on response, but personal invitation by general practitioners produced a 75% response rate in women 50-64 who had failed to attend on the van's previous visit. Attenders found this form of screening both convenient and acceptable.

Adult↗
PubMed1989

The use of QALYs in health care decision making.

This paper seeks to highlight some of the critical issues concerning the use of the Quality Adjusted Life Years (QALYs) to measure the outcome of health care choices, in decisions related to both individual patient care and social resource allocation. Much of the support for the QALY is based on its simplicity as a tool for resolving complex choices. However, it may be the case that the QALY is not sufficiently refined or robust, failing perhaps to take into account some of the critical factors which affect preferences over different health care scenarios.

Chronic Disease↗
PubMed1987

The effect of low-dose oral contraceptives on cardiorespiratory function, coagulation, and lipids in exercising young women: a preliminary report.

A study was undertaken to determine whether low-dose oral contraceptive usage would negate the beneficial effect of exercise on cardiorespiratory fitness, lipid and lipoprotein levels, and coagulation. Twelve exercising women were randomly allocated to groups of either oral contraceptive users or non-oral contraceptive users. When compared with results in the control group, maximal oxygen uptake (ml/kg1 X min1) decreased significantly in the oral contraceptive users during the 6-month period of observation. This was associated with an 8% decrease in both the oxygen uptake (2.34 to 2.17 L/min) and the oxygen pulse (12.1 +/- 3.2 to 11.2 +/- 2.2 ml/beat). The serum cholesterol, triglycerides, high-density lipoprotein/cholesterol, and high-density lipoprotein subfractions 2a and 2b levels were not altered. A significant increase in plasminogen activity was found in the oral contraceptive users: values increased from a coherent time average of 3.8 +/- 0.5 U/ml at baseline to 5.7 +/- 0.7 U/ml at 6 months; values returned to baseline levels 1 month after stopping the oral contraceptives (coherent time average of 3.9 +/- 0.6 U/ml; p less than 0.0001). No other significant changes were noted in the coagulation and anticoagulation factors studied. Low-dose oral contraceptive usage is associated with a decrease in functional aerobic capacity, but it does not impinge on the hemostatic mechanism or lipid-lipoprotein metabolism.

Adult↗
PubMed1985

The effects of low-dose oral contraceptives on coagulation and fibrinolysis in two high-risk populations: young female smokers and older premenopausal women.

A study was undertaken to determine the effect of a low-dose oral contraceptive on the coagulation and inhibitory system of coagulation in 22 young healthy women who smoke and in 15 nonsmoking healthy women between the ages of 34 and 41. Smokers showed statistically significant oral contraceptive-related procoagulant alterations in prothrombin time, thrombin time, and fibrinogen antigen. Antithrombin III antigen and activity were significantly reduced, whereas plasminogen antigen and activity were increased. Inhibitor and fibrinolytic activity was either unaffected or enhanced by oral contraceptives in women over the age of 34: antithrombin III activity was unchanged, plasminogen antigen and activity increased (p less than 0.0007), and alpha 2-antiplasmin was significantly reduced (p less than 0.07). Whereas usage of oral contraceptives in young smokers may initiate biochemical changes in favor of thrombogenesis, their usage in nonsmoking older women enhanced fibrinolysis and had a neutral effect on inhibition and a minimal procoagulant effect.

Adult↗