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We consider the comparison of two treatments (or a treatment and a control/placebo) with responses that are classified into ordinal categories. By operating on the assumption that the responses are manifestations of some underlying continuous variables and that the definitions of the categories for the treatment group and the placebo group are the same in the same clinical test centre, we develop a model to examine the possible treatment effects. These treatment effects can be identified as location effect or dispersion effect. The method can be generalized to analyse clinical test results coming from different centres, where each centre may have its own standard in classifying responses. The method is technically undemanding and can be implemented in a very simple and straightforward way by using easily accessible software that can be downloaded at no cost. Real data sets are analysed for illustration.
Cost data that arise in the evaluation of health care technologies usually exhibit highly skew, heavy-tailed and, possibly, multi-modal distributions. Distribution-free methods for analysing these data, such as the bootstrap, or those based on the asymptotic normality of sample means, may often lead to inefficient or misleading inferences. On the other hand, parametric models that fit the data (or a transformation of the data) equally well can produce very different answers. We consider a Bayesian approach, and model cost data with a distribution composed of a piecewise constant density up to an unknown endpoint, and a generalized Pareto distribution for the remaining tail.
A considerable body of literature has arisen over the past 15 years for analysing univariate repeated measures data. It is rare in applied biomedical research, however, for interest to be restricted to a single outcome measure. In previous work, Rochon considered the case of bivariate repeated measures data in which each outcome is a discrete or continuous random variable. A GEE model was prescribed to relate each set of repeated measures to important explanatory variables. The 'seemingly unrelated regression' model was then applied to combine the pair of GEE models into an overall analysis framework. In this paper, we extend this approach to the case in which one endpoint is a repeated measures outcome but the second is a survival endpoint. Estimation and hypothesis testing issues are addressed and the methodology is illustrated with an example.
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Clinical practice guidelines (CPGs) are suited tools for controlling and improving the effectiveness and efficiency of medical care. With the upcoming internet, the numbers of CPGs have increased rapidly, however, only few offer the attributes of good guidelines such as reliability/reproducibility, applicability, flexibility, clarity, multidisciplinary process, scheduled review and documentation of clinical and scientific evidence. Nearly identical criteria for appraisal of CPGs have been developed in many countries consisting of a checklist with questions concerning the quality of development, the content and format, and the applicability of the guideline. In the United States, guidelines which successfully passed the appraisal (or clearing) process, were stored in the National Guideline Clearinghouse, an internet-based database. A German counterpart is under construction, which will comprise clearing reports reviewing and appraising all existent guidelines covering a medical topic. Developing high-quality CPGs is a time consuming and expensive process. A widely accepted guideline for guideline development was published by the Scottish Intercollegiate Guideline Network. CPGs touching neurosurgical topics are rare and often developed without neurosurgical participation. Due to the potential medico-economic impact of CPGs in the future, national neurosurgical societies and their international associations should play a more active role in the development and implementation of CPGs.
The beneficial effect of chronic beta-blockade in patients with congestive heart failure has been repeatedly shown since its introduction into treatment for this condition in 1975. Still this kind of therapy remains controversial, it is sometimes regarded as a therapeutic paradox, and its use is mainly limited to specialist centers. Various favorable effects of beta-blockers in patients with heart failure due to idiopathic dilated cardiomyopathy and ischemic heart disease have been demonstrated, the principal among them being reduction in energy requirements and ischemia, antiarrhythmogenic effect, improvement of diastolic function, protection of myocytes against catecholamine overload, centrally mediated increase in vagal tone, upregulation of beta-adrenergic receptors, and possible blockade of autoantibodies against beta 1-receptors. Although most of the studies used metoprolol, these effects may be relevant to certain other beta-blockers. Despite very solid pathophysiological and pharmacological rationales for the use of beta-blockade, a major obstacle for a general acceptance of this therapeutic concept is the striking contrast between hemodynamic changes during the acute effect and long-term treatment. When titrated carefully from very low doses and used with a true commitment to long-term treatment, beta-blockers have been shown to prevent further deterioration of heart failure and to improve hemodynamics, exercise tolerance, quality of life, and prognosis.
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Successful treatment of hypertension requires a holistic approach. In this connection, focusing on a healthy lifestyle, eating, drinking and consumption behavior and, finally, the quality of foodstuffs and the exercise habits of the patient represents an essential supplement to the classical forms of pharmaceutical treatment. The major dietary-physiological factors have been shown to be weight reduction, the monitoring of salt consumption, appropriate intake of fiber, a preference for vegetables, and a reduction of immoderate alcohol consumption.
Evidence-based medicine is a new approach to improve the transfer process of knowledge from research to medical practice. The assumption that only results of randomized controlled studies are evident is true for many but by far not for all clinical problems. As is demonstrated from one historical and many recent examples, there exists another but equally stringent method of proof which is based on an implicit historical comparison. This kind of evidence still has to be defined exactly in order to protect it from misuse by alternative medicine. The statement that only 20% of methods used in conventional medicine are [corrected] evidence-based cannot be substantiated. Methods and importance of meta-analyses are critically discussed as well as the meaning of the term publication bias. The new documentation- and information techniques will improve some steps in the transfer process. At the end it will be crucial whether the last step, the improvement of rationality in patient care, will be successful. This evidence still has to be demonstrated.
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The superficial femoral artery (SFA) is a unique vessel in terms of its anatomy, its function and its interventional requirements; it has no comparison in any other arterial vascular bed. It is a long conduction vessel with a high flow resistance underlying several different hemodynamic conditions. In the past 15 years the unique characteristics of the SFA have resulted in poor interventional outcomes, with mid-term restenosis rates in the order of 50%--outcomes that are worse than in any other arterial vascular bed. In view of the clinical importance of SFA treatment, which comprises about 50% of all interventions at peripheral arterial lesions, considerable efforts have been made with a variety of interventional techniques to achieve progress. Only the use of self-expanding nitinol stents appears to improve the mid-term results of catheter-based interventional SFA treatment.
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