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Biomedical subjects

C D Naylor

Publications and source records attributed to C D Naylor.

At least 199 records · Page 11Linked to original sources
PubMed1989

Parenteral nutrition with branched-chain amino acids in hepatic encephalopathy. A meta-analysis.

Meta-analytic methods were applied to review clinical trials published in English that have assessed the efficacy of parenteral nutrition for cirrhotic patients with acute hepatic encephalopathy. Modified amino acid solutions containing increased amounts of branched-chain amino acids were used as part of the treatment regimen in all studies. Pooled analysis of five randomized controlled studies showed a highly significant improvement in mental recovery (p less than 0.001) from high-grade encephalopathy over follow-up times varying from 5 to 14 days. The significance level of the treatment effect did not change when the analysis was repeated using alternative methods of counting and attributing events in these trials. Sharp differences in direction of treatment effect precluded pooling case fatality data. Two studies reported an increased risk of death in the treatment group. Two others showed a clear benefit from administration of parenteral nutrition: the aggregate relative risk reduction was 0.59 (95% confidence interval: 0.23-0.80, p = 0.002). Addition of unpublished data from a third positive study increased the relative risk reduction to 0.82 (p less than 0.0001), and the most conservative interpretation of the published data still yielded a significant reduction in mortality (p = 0.023). However, given the uncertainty about effects on mortality and short follow-up times in all studies, a confirmatory randomized controlled trial with longer follow-up periods is warranted.

Adolescent↗
PubMed1989

The role of platelets in progressive glomerulosclerosis: mechanisms for intraglomerular platelet activation and pathogenetic consequences.

Purkerson et al. have hypothesized that platelet aggregation and release reactions contribute to the progressive sclerosis of remnant nephrons. The suggested mechanism for platelet activation is disruption of endothelium by the high hydraulic pressures characteristic of remnant nephrons, with platelet exposure to basement membrane collagen. We herein postulate additional mechanisms whereby platelets might be activated in the microcirculation of remnant nephrons: (i) kinetic activation due to high plasma flow rates; (ii) close cell contact due to concentration of blood cells and platelets in the glomerulus; (iii) concentration of protein macromolecules that act as agonists for platelet release; (iv) glomerular release of saturated and monenoic fatty acids that stimulate platelet synthesis of thromboxane A2; (v) glomerular release of membrane-bound pro-coagulant factor, triggering a chain reaction that activates both platelets and the intraglomerular coagulation cascade. Platelet activation could play a pathogenetic role in many of the known derangements of structure and function in remnant nephrons. This paradigm may also be partially applicable to the glomerulosclerosis of diabetes mellitus.

Animals↗
PubMed1989

Diagnosing gestational diabetes mellitus. Is the gold standard valid?

In North America, gestational diabetes mellitus (GDM) is diagnosed from a 100-g oral glucose tolerance test (OGTT) with criteria proposed by the National Diabetes Data Group (NDDG). These criteria were derived in the 1950s from an unrepresentative sample of women tested predominantly in the latter stages of pregnancy. The original studies did not check for reproducibility of OGTT results. Measurements were made with the Somogyi-Nelson whole-blood glucose technique, and test translation errors are present in the threshold values proposed for modern plasma glucose oxidase methods. Whereas GDM is now diagnosed with a view to adverse maternal-fetal outcomes, the criteria were chosen to reflect maternal risk of developing glucose intolerance as shown by a 75-g OGTT in the nonpregnant state over the ensuing 8 yr. For that outcome, the positive predictive value of the criteria was only 36.1%, and this is a marked overestimate, because the study cohort was a highly selected group with an increased incidence of glucose intolerance both during and after pregnancy. The criteria are also conceptually flawed in that they impose a dichotomous definition of normal and abnormal on gestational glucose tolerance, when the risk of adverse maternal-fetal outcomes and later diabetes mellitus should logically be graded upward with higher values on the gestational OGTT and with the degree of fasting hyperglycemia. Although NDDG criteria merit continued use for lack of a better alternative, new diagnostic criteria for GDM should be derived and validated.

Blood Glucose↗
PubMed1988

Private medicine and the privatisation of health care in South Africa.

Health services in the Republic of South Africa (RSA) are provided by a mixture of public and private providers and institutions. Estimates of total health-related expenditure for 1985 range between 5.3% and 5.9% of gross national product (GNP), divided on approximately a 55:45 basis between public and private sectors. Basic preventive and curative services are provided by a hospital- and clinic-based public system. The public system does not adequately serve the rural areas and African tribal bantustans, and racial discrimination and/or segregation are obvious in its organisation and funding. The public sector's strength is the provision of state-subsidised care to many citizens who are unable to afford private medicine. The vast majority of hospitals are operated on a non-profit basis by government, industries, and voluntary agencies. Excluding hospitals that receive state subsidies, private investor-owned hospitals control about 10% of all hospital beds in the RSA. One-third of these investor-owned beds are held by state-dependent contractors providing long-term care. Two-thirds are wholly independent. Growth has been rapid in the independent hospital sector, and major corporations have entered the market. In 1985, over 85% of the white population was privately insured by a variety of prepayment programmes, including those organised through parastatal corporations and government departments. Despite major enrollment growth in the preceding decade, only 8% of blacks held private insurance by 1985; their coverage also tended to be less comprehensive. Faced with deficit financing, a sluggish economy, complaints from its white constituency about taxation levels, and pressure from private sector interest groups, the Nationalist government has endorsed the concept of privatisation of health care. Exponents of privatisation claim that it will permit differentiation by income to supplant discrimination by race. However, the direct links between disposable income and race, the rapidly rising costs of private insurance, and the still-limited extent of private coverage among the black majority, indicate that privatisation is likely to co-opt a comparatively small proportion of the total black population. It may exacerbate the urban-rural imbalance in health status and health services, promote growth of hospital-intensive curative services rather than needed expansion of community-centred preventive and primary care, and create financial barriers to access for low-income patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Health Services Administration↗
PubMed1987

Privatisation of South African health services--are the underlying assumptions correct?

Six key assumptions made by proponents of privatisation are critically appraised in the light of Canadian, US and UK studies. 'Counter' assumptions, equally credible, are: (i) the economic behaviour of the health-care market does not correspond to the idealized rules of the free market nor, given the nature of health care as a 'public good', should it do so; (ii) national health-care systems with a heavy emphasis on private insurance are as or more costly than universal public systems; (iii) private for-profit hospitals do not usually enjoy any cost-efficiency advantages over public hospitals; (iv) subsidizing individuals to purchase private care carries a risk of adding administrative costs, fueling the inflationary spiral in health care, and reducing public accountability of tax money; (v) user-fees and co-insurance will not deter over-utilisation without penalising and reducing legitimate use of health services; and (vi) savings from privatisation are unlikely except for the more affluent citizens of the RSA who will carry a slightly reduced tax burden--all others will pay more and may be deterred from seeking necessary care.

Canada↗
PubMed1987

The midclavicular line: a wandering landmark.

Although the midclavicular line (MCL) is the usual reference point for clinical assessment of liver size and localization of the cardiac apex beat, we found substantial interobserver variation in locating the MCL. The distance from the midline to the MCL as estimated by 20 clinicians in three subjects varied by up to 10 cm. More variation was found for estimates in the obese subject than for those in the two subjects of normal build (p = 0.004). No difference in variation was found between consultants and house staff. The limitations of the MCL as a reference point are discussed in light of these findings.

Cardiomegaly↗
PubMedDate not supplied

Mismatch of coronary risk and treatment intensity under the National Cholesterol Education Program guidelines.

OBJECTIVE: To assess the match between multifactorial risk of coronary heart disease (CHD) and treatment intensity under the National Cholesterol Education Program (NCEP) guidelines for primary prevention of CHD. METHODS: The multiple logistic regression equation from the Framingham Study was used to derive predicted risks for development of CHD over eight years of follow-up for different age-gender groupings, with serum total cholesterol (TC) values chosen in light of the NCEP cutoff points for both TC and low-density-lipoprotein cholesterol levels. Additional risk factors--hypertension, glucose intolerance, and smoking--were considered in combination for each of these values. RESULTS: Controlling for the effects of age and gender, there is little difference in the ranges of absolute CHD risks for persons who would receive interventions of differing intensities (i.e., general dietary advice, dietary treatment, or drug therapy). Those who are candidates for drug treatment because of serum lipids alone are often at low levels of risk for the development of CHD when compared with those of the same age with lower TC values who have other risk factors. Discrepancies in CHD risk are wider still when age is also allowed to vary. Furthermore, in every age grouping, women with high TC levels (e.g., 6.9 mmol/L) and two other risk factors are eligible for drug treatment but have a CHD risk that is no higher, and often much lower, than that of males with one other risk factor and TC levels of 4.8 mmol/L or 5.7 mmol/L who are candidates for dietary advice or dietary therapy, respectively. CONCLUSIONS: Inconsistencies exist in the NCEP guidelines such that persons at low risk for the development of CHD are offered more intensive interventions than are other who actually are at much higher risks, and vice versa. Women in particular tend to be overtreated, relative to men. These findings point out the difficulties of promulgating guidelines that will appropriately match risk to preventive interventions in a complex multifactorial disease.

Adult↗
PubMedDate not supplied

Placing patients in the queue for coronary surgery: do age and work status alter Canadian specialists' decisions?

OBJECTIVE: To determine the effects of age and work status on whether and where cardiovascular specialists would place hypothetical patients in the queue for coronary surgery. MATERIALS AND METHODS: Mailed survey presenting a set of clinical scenarios either to be rated on a scale with 7 time frames for urgency of need or to be designated as questionable/inappropriate for intervention. The basic scenario was a patient with mild-moderate stable angina, good left ventricular function, and limited coronary disease; operative risks and stress test results were varied. Three identifiers were used: "45-year-old civil servant gainfully employed"; "45-year-old laborer disabled by angina, faces job loss"; and "75-year-old retiree, angina limits golf." PARTICIPANTS: Cardiologists and cardiac surgeons practicing in five Ontario medical centers (n = 120). RESULTS: There was a 59% response rate (120 usable responses). Large shifts in willingness to intervene occurred in favor of the disabled laborer (p less than 0.0001) and against the retiree (p-value ranges from 0.04 to less than 0.0001, depending on operative risk and stress test results), but not for the employed civil servant. Striking effects (p less than 0.0001) were also evident in ratings of waiting time, with the order of priority being the disabled laborer first, the civil servant second, and the retiree last. The overall mean shift due to work status or age was equal to, or larger than, the mean shift due to clinical factors, such as stress test results, changes in severity of stable angina, and extent of coronary disease. CONCLUSION: Cardiovascular specialists may place considerable weight on age and work status in determining urgency and appropriateness of coronary revascularization. Risk-benefit concerns may partly explain shifting thresholds for intervention, but not differential waiting times. The influence of these factors should be sought in utilization audits and addressed from an ethical perspective.

Age Factors↗