Abstract:
:We present a class of simple designs that can be used in early dose-finding studies in HIV. Such designs, in contrast with Phase I designs in cancer, have a lot of the Phase II flavor about them. Information on efficacy is obtained during the trial and is as important as that relating to toxicity. The designs proposed here sequentially incorporate the information obtained on viral reduction. Initial doses are given from some fixed range of dose regimens. The doses are ordered in terms of their toxic potential. At any dose, a patient can have one of three outcomes: inability to take the treatment (toxicity), ability to take the treatment but insufficient reduction in viral load (viral failure), and ability to take the treatment as well as a sufficient reduction of viral load (success). A clear goal for some class of designs would be the identification of the dose leading to the greatest percentage of successes. Under certain assumptions, which we identify and discuss, we can obtain efficient designs for this task. Under weaker, sometimes more realistic assumptions, we can still obtain designs that have good operating characteristics in identifying a level, if such a level exists, having some given or greater success rate. In the absence of such a level, the designs will come to an early closure, indicating the ineffectiveness of the new treatment.
journal_name
Biometricsjournal_title
Biometricsauthors
O'Quigley J,Hughes MD,Fenton Tdoi
10.1111/j.0006-341x.2001.01018.xsubject
Has Abstractpub_date
2001-12-01 00:00:00pages
1018-29issue
4eissn
0006-341Xissn
1541-0420journal_volume
57pub_type
杂志文章相关文献
BIOMETRICS文献大全abstract::Recent developments in the animal breeding literature facilitate estimation of the variance components in quantitative genetic models. However, computation remains intensive, and many of the procedures are restricted to specialized designs and models, unsuited to data arising from studies of natural populations. We de...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1990-06-01 00:00:00
abstract::This article develops a variety of influence measures for carrying out perturbation (or sensitivity) analysis to joint models of longitudinal and survival data (JMLS) in Bayesian analysis. A perturbation model is introduced to characterize individual and global perturbations to the three components of a Bayesian model...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2012.01745.x
更新日期:2012-09-01 00:00:00
abstract::This article develops a latent model and likelihood-based inference to detect temporal clustering of events. The model mimics typical processes generating the observed data. We apply model selection techniques to determine the number of clusters, and develop likelihood inference and a Monte Carlo expectation-maximizat...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2009.01197.x
更新日期:2009-12-01 00:00:00
abstract::A general formula for the frequency of different recombinant gamete types, in terms of the underlying distribution of crossovers, is derived. This formula may be applied to any theoretical model of recombination in which it is assumed that there is no chromatid interference. Multiple-locus recombination data may be ev...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1983-12-01 00:00:00
abstract::Tag loss in mark-recapture experiments is a violation of one of the Jolly-Seber model assumptions. It causes bias in parameter estimates and has only been dealt with in an ad hoc manner. We develop methodology to estimate tag retention and abundance in double-tagging mark-recapture experiments. We apply this methodolo...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2006.00523.x
更新日期:2006-09-01 00:00:00
abstract::A class of adaptive weighted log-rank statistics is described where the vector of weights is chosen in a data-dependent way from a family of "smooth" weight vectors. A parametric family of weight vectors is identified which includes most shapes of weighting vectors that will be near optimal in many cancer prevention a...
journal_title:Biometrics
pub_type: 临床试验,杂志文章,随机对照试验
doi:
更新日期:1991-09-01 00:00:00
abstract::This article introduces an original methodology based on empirical likelihood, which aims at combining different food contamination and consumption surveys to provide risk managers with a risk measure, taking into account all the available information. This risk index is defined as the probability that exposure to a c...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2008.01051.x
更新日期:2009-03-01 00:00:00
abstract::A considerable body of literature has arisen over the past 15 years for analyzing univariate repeated measures data. However, it is rare in applied biomedical research for interest to be restricted to a single outcome measure. In this paper, we consider the case of bivariate repeated measures. We apply a generalized e...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1996-06-01 00:00:00
abstract::Image-on-image regression analysis, using images to predict images, is a challenging task, due to (1) the high dimensionality and (2) the complex spatial dependence structures in image predictors and image outcomes. In this work, we propose a novel image-on-image regression model, by extending a spatial Bayesian laten...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.13420
更新日期:2020-12-27 00:00:00
abstract::Prognostic models in survival analysis typically aim to describe the association between patient covariates and future outcomes. More recently, efforts have been made to include covariate information that is updated over time. However, there exists as yet no standard approach to assess the predictive accuracy of such ...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2007.00889.x
更新日期:2008-06-01 00:00:00
abstract::A log-linear model for estimating the size of a closed population is defined for inverse multiple-recapture sampling with dependent samples. Efficient estimators of the log-linear model parameters and the population size are obtained by the method of minimum chi-square. A chi-square test of the general linear hypothes...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1987-12-01 00:00:00
abstract::A method purporting to provide optimal allocations in bioequivalence studies fails to do so on both statistical and practical grounds. Reasons as to why this is so are given. ...
journal_title:Biometrics
pub_type: 评论,杂志文章
doi:10.1111/j.0006-341x.1999.01314.x
更新日期:1999-12-01 00:00:00
abstract::Because the number of patients waiting for organ transplants exceeds the number of organs available, a better understanding of how transplantation affects the distribution of residual lifetime is needed to improve organ allocation. However, there has been little work to assess the survival benefit of transplantation f...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.12084
更新日期:2013-12-01 00:00:00
abstract::Treatments are frequently evaluated in terms of their effect on patient survival. In settings where randomization of treatment is not feasible, observational data are employed, necessitating correction for covariate imbalances. Treatments are usually compared using a hazard ratio. Most existing methods which quantify ...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.12542
更新日期:2017-03-01 00:00:00
abstract::Estimating the number of clusters in a data set is a crucial step in cluster analysis. In this article, motivated by the gap method (Tibshirani, Walther, and Hastie, 2001, Journal of the Royal Statistical Society B63, 411-423), we propose the weighted gap and the difference of difference-weighted (DD-weighted) gap met...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2007.00784.x
更新日期:2007-12-01 00:00:00
abstract::We estimate how the effect of antiretroviral treatment depends on the time from HIV-infection to initiation of treatment, using observational data. A major challenge in making inferences from such observational data arises from biases associated with the nonrandom assignment of treatment, for example bias induced by d...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2011.01738.x
更新日期:2012-09-01 00:00:00
abstract::Dynamic treatment regimes (DTRs) aim to formalize personalized medicine by tailoring treatment decisions to individual patient characteristics. G-estimation for DTR identification targets the parameters of a structural nested mean model, known as the blip function, from which the optimal DTR is derived. Despite its po...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.13104
更新日期:2019-12-01 00:00:00
abstract::In this paper we consider the use of within-subject coefficient of variation (WCV) for assessing the reproducibility or reliability of a measurement. Application to assessing reproducibility of biochemical markers for measuring bone turnover is described and the comparison with intraclass correlation is discussed. Bot...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1996-12-01 00:00:00
abstract::Spatial replication is a common theme in count surveys of animals. Such surveys often generate sparse count data from which it is difficult to estimate population size while formally accounting for detection probability. In this article, I describe a class of models (N-mixture models) which allow for estimation of pop...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.0006-341X.2004.00142.x
更新日期:2004-03-01 00:00:00
abstract::A common measure in clinical trials and epidemiologic studies is the number of events such as seizures, hospitalizations, or bouts of disease. Frequently, a binary measure of severity for each event is available but is not incorporated in the analysis. This paper proposes methodology for jointly modeling the number of...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1997-09-01 00:00:00
abstract::Restricted maximum likelihood (REML) is now well established as a method for estimating the parameters of the general Gaussian linear model with a structured covariance matrix, in particular for mixed linear models. Conventionally, estimates of precision and inference for fixed effects are based on their asymptotic di...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1997-09-01 00:00:00
abstract::This article presents a new approach for exploring the distribution of interindividual random effects in nonlinear mixed effect models. The approach introduces a spline function, which transforms an assumed normally distributed interindividual random effect to an arbitrary distribution approximating that of the data. ...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1995-12-01 00:00:00
abstract:SUMMARY:In this article we investigate regression calibration methods to jointly model longitudinal and survival data using a semiparametric longitudinal model and a proportional hazards model. In the longitudinal model, a biomarker is assumed to follow a semiparametric mixed model where covariate effects are modeled p...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2007.00983.x
更新日期:2008-12-01 00:00:00
abstract::Morrissey and Spiegelman (1999, Biometrics 55, 338 344) provided a comparative study of adjustment methods for exposure misclassification in case-control studies equipped with an internal validation sample. In addition to the maximum likelihood (ML) approach, they considered two intuitive procedures based on proposals...
journal_title:Biometrics
pub_type: 评论,杂志文章
doi:10.1111/j.0006-341x.2002.1034_1.x
更新日期:2002-12-01 00:00:00
abstract::We describe group sequential tests for a bivariate response. The tests are defined in terms of the two response components jointly, rather than through a single summary statistic. Such methods are appropriate when the two responses concern different aspects of a treatment; for example, one might wish to show that a ne...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1993-09-01 00:00:00
abstract::This article demonstrates semiparametric maximum likelihood estimation of a nonlinear growth model for fish lengths using imprecisely measured ages. Data on the species corvina reina, found in the Gulf of Nicoya, Costa Rica, consist of lengths and imprecise ages for 168 fish and precise ages for a subset of 16 fish. T...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.0006-341x.2002.00448.x
更新日期:2002-06-01 00:00:00
abstract::We present a natural generalization of the Buckley-James-type estimator for traditional survival data to right-censored length-biased data under the accelerated failure time (AFT) model. Length-biased data are often encountered in prevalent cohort studies and cancer screening trials. Informative right censoring induce...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2011.01568.x
更新日期:2011-12-01 00:00:00
abstract::Objective measures of oxygen consumption and carbon dioxide production by mammals are used to predict their energy expenditure. Since energy expenditure is not directly observable, it can be viewed as a latent construct with multiple physical indirect measures such as respiratory quotient, volumetric oxygen consumptio...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.12706
更新日期:2018-03-01 00:00:00
abstract::We derive a likelihood score method for interval estimation of the intraclass version of the kappa coefficient of agreement with binary classification using a general theory of Bartlett (1953, Biometrika 40, 306-317). By exact evaluation, we investigate statistical properties of the score method, the chi-square goodne...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.0006-341x.2000.00583.x
更新日期:2000-06-01 00:00:00
abstract::Ophthalmologic studies often compare several groups of subjects for the presence or absence of some ocular finding, where each subject may contribute two eyes to the analysis, the values from the two eyes being highly correlated. Rosner (1982, Biometrics 38, 105-114) and Dallal (1988, Biometrics 44, 253-257) proposed ...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1989-06-01 00:00:00