Abstract:
:This paper discusses the various philosophies that influence the selection of patients for entry into randomized controlled trials. Although a number of different and often competing issues have to be considered depending upon the trial, keeping entry criteria simple, wide and at times even flexible is usually preferable. Such a strategy can be a positive virtue by helping to attain the large numbers of patients that are usually needed to reliably detect the sorts of moderate benefits that are plausible, at a reasonable cost and by providing answers that are relevant to many different categories of patients with a particular condition.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Yusuf S,Held P,Teo KK,Toretsky ERdoi
10.1002/sim.4780090114subject
Has Abstractpub_date
1990-01-01 00:00:00pages
73-83; discussion 83-6issue
1-2eissn
0277-6715issn
1097-0258journal_volume
9pub_type
杂志文章abstract::It is often assumed that randomisation will prevent bias in estimation of treatment effects from clinical trials, but this is not true of the semiparametric Proportional Hazards model for survival data when there is underlying risk heterogeneity. Here, a new formula is proposed for estimation of this bias, improving o...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7343
更新日期:2017-09-20 00:00:00
abstract::A preference trial is a special form of cross-over trial where clinical conditions determine when patients change treatment, in a prescribed order. This can be modelled using a geometric distribution. The model can be simply fitted using standard logistic regression methodology. The procedure is applied to a trial stu...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(SICI)1097-0258(19960229)15:4<443::AID-SIM
更新日期:1996-02-28 00:00:00
abstract::We examine Goodman and Kruskal's lambda using Efron's approach to regression and analysis of variance (ANOVA) for zero-one outcome data. For a binary response cross-classified by a single nominal predictor, we present a computationally simple ANOVA table in which lambda is analogous to Pearson's R-square. We character...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780080511
更新日期:1989-05-01 00:00:00
abstract::Statistical tests have been proposed for determining whether incident cases of adverse health effects are 'clustered' together. Several procedures, termed 'focused', specifically analyse disease surveillance data around pre-specified putative sources of environmental hazard. Little has been done to compare the perform...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780142103
更新日期:1995-11-15 00:00:00
abstract::Population heterogeneity is frequently observed among patients' treatment responses in clinical trials because of various factors such as clinical background, environmental, and genetic factors. Different subpopulations defined by those baseline factors can lead to differences in the benefit or safety profile of a the...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7925
更新日期:2018-12-20 00:00:00
abstract::This paper, arising out of an event to honour the statistical and scientific contributions of Professor Peter Armitage, is concerned with research strategies and needs for chronic disease prevention. A few highlights from recent intervention trials for the prevention of cancer, cardiovascular disease, fractures and di...
journal_title:Statistics in medicine
pub_type:
doi:10.1002/sim.2045
更新日期:2004-11-30 00:00:00
abstract::We propose a probability distribution for an equivalence class of classification trees (that is, those that ignore the value of the cutpoints but retain tree structure). This distribution is parameterized by a central tree structure representing the true model, and a precision or concentration coefficient representing...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990330)18:6<727::aid-sim
更新日期:1999-03-30 00:00:00
abstract::Longitudinal studies are often concerned with estimating the recurrence rate of a non-fatal event. In many cases, only the total number of events occurring during successive time intervals is known. We compared a mixed Poisson-gamma regression method proposed by Thall and a quasi-likelihood method proposed by Zeger an...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1002/sim.4780121406
更新日期:1993-07-30 00:00:00
abstract::The two tailed Fisher's exact P value is extremely sensitive to small perturbations in 2 x 2 contingency tables. An example indicates that a 1 per cent increase in the denominator of one treatment group results in a 32 per cent drop in the exact P value, but a mere 0.1 per cent decrease in the treatment success rate. ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780050610
更新日期:1986-11-01 00:00:00
abstract::In this paper, we consider pooling schemes in which samples are to be tested in two-stages. We show that when batch size is limited as well as pool size, selection schemes tend to be more efficient and flexible. Formulae for the efficiencies of square arrays in all dimensions and for all selection schemes are given in...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3965
更新日期:2010-09-20 00:00:00
abstract::We estimate a Cox proportional hazards model where one of the covariates measures the level of a subject's cognitive functioning by grading the total score obtained by the subject on the items of a questionnaire. A case study is presented where the sample includes partial respondents, who did not answer some questionn...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3773
更新日期:2010-01-30 00:00:00
abstract::We present some practical extensions and applications of a strategy proposed by Thall, Simon and Estey for designing and monitoring single-arm clinical trials with multiple outcomes. We show by application how the strategy may be applied to construct designs for phase IIA activity trials and phase II equivalence trial...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19980730)17:14<1563::aid-s
更新日期:1998-07-30 00:00:00
abstract::The analysis and recognition of disease clustering in space and its representation on a map is an important problem in epidemiology. An approach using mixture models to identify spatial heterogeneity in disease risk and map construction within an empirical Bayes framework is described. Once heterogeneity is detected, ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19960415)15:7/9<919::aid-s
更新日期:1996-04-15 00:00:00
abstract::Many neuroscientists are interested in how connectomes (graphical representations of functional connectivity between areas of the brain) change in relation to covariates. In statistics, changes like this are analyzed using regression, where the outcomes or dependent variables are regressed onto the covariates. However...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8374
更新日期:2019-12-20 00:00:00
abstract::The Response Evaluation Criteria in Solid Tumors are used as standard guidelines for the clinical evaluation of cancer treatments. The assessment is based on the anatomical tumor burden: change in size of target lesions and evolution of nontarget lesions (NTL). Despite unquestionable advantages of this standard tool, ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7640
更新日期:2018-06-15 00:00:00
abstract::We investigate population-averaged (PA) and cluster-specific (CS) associations for clustered binary logistic regression in the context of a longitudinal clinical trial that investigated the association between tooth-specific visual elastase kit results and periodontal disease progression within 26 weeks of follow-up. ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780140407
更新日期:1995-02-28 00:00:00
abstract::Analyses to compare non-randomized groups are more and more common in both post hoc analyses of randomized clinical trials data and in analyses of long-term observational data. In such cases, it is quite likely that there are unknown or uncollected sources of heterogeneity in event rates. Research has shown that an un...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1795
更新日期:2004-07-15 00:00:00
abstract::Missing data arise in crossover trials, as they do in any form of clinical trial. Several papers have addressed the problems that missing data create, although almost all of these assume that the probability that a planned observation is missing does not depend on the value that would have been observed; that is, the ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4497
更新日期:2012-07-20 00:00:00
abstract::We obtained maximum likelihood estimates (MLEs) of the proportion cured pi c and mean log survival time mu t for a sample of 4355 patients with intraocular melanoma whose survival times subsequent to treatment were assumed to follow a log-normal distribution. Following stratification by tumour size, MLEs of pi c and m...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780090814
更新日期:1990-08-01 00:00:00
abstract::Most statistical methodology for phase III clinical trials focuses on the comparison of a single experimental treatment with a control. An increasing desire to reduce the time before regulatory approval of a new drug is sought has led to development of two-stage or sequential designs for trials that combine the defini...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1362
更新日期:2003-03-15 00:00:00
abstract::The semi-Markov assumption emphasizes the importance of time spent in a state. In order to compute this type of multistate model, most transition times are always considered to be exactly identified or right censored. However, in the longitudinal analysis of chronic diseases, investigators are often confronted with in...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3100
更新日期:2007-12-30 00:00:00
abstract::Hospital length of stay (LOS) is an important measure of healthcare utilization and is generally positively skewed and heterogeneous. We fit a Coxian phase-type distribution to LOS and identify the hidden states of the underlying latent homogeneous Markov model. We demonstrate that selecting an appropriate number of p...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4490
更新日期:2012-06-30 00:00:00
abstract::The generalized estimating equations (GEE) approach is commonly used to model incomplete longitudinal binary data. When drop-outs are missing at random through dependence on observed responses (MAR), GEE may give biased parameter estimates in the model for the marginal means. A weighted estimating equations approach g...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1241
更新日期:2002-10-30 00:00:00
abstract::Biomarkers that predict the efficacy of treatment can potentially improve clinical outcomes and decrease medical costs by allowing treatment to be provided only to those most likely to benefit. We consider the design of a randomized clinical trial in which one objective is to evaluate a treatment selection marker. The...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6564
更新日期:2015-11-30 00:00:00
abstract::In record linkage studies, unique identifiers are often not available, and therefore, the linkage procedure depends on combinations of partially identifying variables with low discriminating power. As a consequence, wrongly linked covariate and outcome pairs will be created and bias further analysis of the linked data...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5498
更新日期:2012-12-30 00:00:00
abstract::In a longitudinal study of workers in seven Norwegian aluminium plants, the time to development of asthmatic symptoms could only be determined to lie in the interval between two consecutive health examinations. In a previous paper we analysed the data by survival techniques for interval censored data. In the present p...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780131708
更新日期:1994-09-15 00:00:00
abstract::Identification of key factors associated with the risk of developing cardiovascular disease and quantification of this risk using multivariable prediction algorithms are among the major advances made in preventive cardiology and cardiovascular epidemiology in the 20th century. The ongoing discovery of new risk markers...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2929
更新日期:2008-01-30 00:00:00
abstract::Conditional power and predictive power provide estimates of the probability of success at the end of the trial based on the information from the interim analysis. The observed value of the time to event endpoint at the interim analysis could be biased for the true treatment effect due to early censoring, leading to a ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7673
更新日期:2018-08-15 00:00:00
abstract::We discuss some of the statistical approaches to the design and analysis of phase I clinical trials in cancer. An attempt is made to identify the issues, particular to this type of trial, that should be addressed by an appropriate methodology. A brief review of schemes currently in use is provided together with our vi...
journal_title:Statistics in medicine
pub_type: 杂志文章,评审
doi:10.1002/sim.4780101104
更新日期:1991-11-01 00:00:00
abstract::We consider the problem of identifying a subgroup of patients who may have an enhanced treatment effect in a randomized clinical trial, and it is desirable that the subgroup be defined by a limited number of covariates. For this problem, the development of a standard, pre-determined strategy may help to avoid the well...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4322
更新日期:2011-10-30 00:00:00