摘要:

AbstractThe present study was initiated by data on the anatomical occurrence of metastases from breast cancer. Metastases may occur at various organs, here grouped into ten categories, and simultaneous occurrences at several sites are common. Our aim was to identify and compare risk factors for development of metastases at each site.The influence of the various risk factors for recurrence at one specific site can be modelled as a standard competing risk problem, using well‐established survival analysis techniques such as the Cox regression model. Recently a generalization to joint occurrences at more than one site has been proposed. The more general models allowcomparisonof the differential prognostic influence of various risk factors on recurrence at different sites.We applied these methods to data from the Danish Breast Cancer Cooperative Group on recurrence after breast cancer, and examined the effect of degree of anaplasia, number of positive lymph nodes, size of primary tumour, skin or deep fascial invasion, age of the patient and adjuvant treatment regimen, as possible risk factors.There were no differential effects of type of therapy on recurrence in different sites. However, chemotherapy had a marginally significant positive effect at all sites. Moreover the number of positive lymph nodes was associated with an increased risk of metastases, homogenous across sites, except for brain where an opposing trend was found. Similarly the degree of anaplasia was associated with a somewhat increased risk of metastases, homogenous except for brain. For brain metastases a significantly more pronounced effect of degree of anaplasia was found.Comparison of the results obtained from the two types of models reveals that the new more general models confirm fewer differences between the influence of the prognostic factors than the traditional regression models sugges

ISSN:0277-6715    

DOI:10.1002/sim.4780110302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA non‐homogeneous Markov chain model is used to describe the evolution of a progressive chronic disease. Transition probabilities are estimated from data on coronary heart disease in Australia. By varying the transition probabilities, the effects of changes in medical management or in the natural history of the disease are examined. For reducing rates of fatal and non‐fatal acute myocardial infarction a multifaceted strategy of primary and secondary prevention and improved acute care is found most effective. Primary prevention reducing the risk of early stages of the disease has the potential to yield the highest proportion of disease‐free people. By contrast, intensive medical treatment of acute disease would reduce mortality but increase the total burden of disease in the popul

ISSN:0277-6715    

DOI:10.1002/sim.4780110303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractLarge‐scale public health trials are often randomized by geographic or administrative clusters, for reasons of financial or organizational exigency. In this paper, we deal with the situation where the dependent variable is a count of events, such as mortality from, or incidence of a given disease. Simulation results show that this design may decrease power by more than 50 per cent. The lost power can largely be replaced by incorporating information on the dependent variable, within clusters, before the start of the trial. The pretrial and trial data can be analysed by negative trinomial model

ISSN:0277-6715    

DOI:10.1002/sim.4780110304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWhen faced with a decision whether or not to treat a patient, to enter or to withdraw a patient from a clinical trial, or any other such binary decision, based on diagnosis with unsatisfactory reliability, can a consensus diagnosis be used to improve reliability? If so, exactly how? That is the question I address here. I draw comparisons and contrasts between the known results with an interval consensus and those with a binary consensus and suggest tactics for use in a pilot study to answer the above questions.

ISSN:0277-6715    

DOI:10.1002/sim.4780110305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractIndices of distributional shape based on linear combinations of order statistics have recently been described by Hosking. Their usefulness as tools for practical data analysis is examined. They are found to have several advantages over the conventional indices of skewness and kurtosis (√b1andb2) and no serious drawbacks. It is proposed, therefore, that they should replace √b1andb2in routine data analysis. To implement this suggestion, action by the developers of standard statistical software is nee

ISSN:0277-6715    

DOI:10.1002/sim.4780110306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractRegistries of clinical trials are a potentially useful resource for the planning of new studies, the promotion of communication and collaboration between researchers, the conduct of meta‐analyses, and the facilitation of patient access and recruitment to trials. However, many physicians and researchers are unaware of their existence, and as a result they remain underused. A directory of registries of clinical trials has been developed as a result of an international survey of 63 organizations and 51 individuals in 13 different countries to identify the existence of such registries. This is intended as a resource to keep physicians, researchers, trial organizers, funding bodies and government agencies abreast of the growing number of registries available, and to assist in the planning of future registries. Twenty‐four current and six planned registries of clinical trials have been identified. Most focus on AIDS or oncology, but such diverse areas as neurosurgery, cardiovascular disease, dentistry and perinatology are also represented. This paper presents a descriptive profile on each registry and discusses the relative merits of their different organizational features. Recommendations are given for the establishment of future registr

ISSN:0277-6715    

DOI:10.1002/sim.4780110307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780110308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780110301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY