Abstract:
:A trial of Duchenne muscular dystrophy involved tracking boys of all ages through a one-year baseline period, followed by a one-year trial of leucine versus placebo treatment. In this paper we develop a model for a total-muscle-strength score that uses the data of the extended baseline period in the evaluation of the leucine treatment. The model is based on a polynomial growth curve in age whose coefficients can vary according to treatment or phase. Maximum likelihood estimates of the parameters of the model are obtained from use of the EM algorithm. We propose tests for the adequacy of the model as well as for treatment effects. A quadratic model appears the most parsimonious fit to the data and there is no evidence of any leucine effect on scores. We examine the asymptotic power of the test for treatment effect and compare it with that of a simpler analysis.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Madsen KS,Miller JP,Province MAdoi
10.1002/sim.4780050304subject
Has Abstractpub_date
1986-05-01 00:00:00pages
231-41issue
3eissn
0277-6715issn
1097-0258journal_volume
5pub_type
临床试验,杂志文章,随机对照试验abstract::Clinical trials studying treatments for rare diseases are challenging to design and conduct due to the limited number of patients eligible for the trial. One design used to address this challenge is the small n, sequential, multiple assignment, randomized trial (snSMART). We propose a new snSMART design that investiga...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8813
更新日期:2021-02-20 00:00:00
abstract::In clinical trials, treatment comparisons are often performed by models that incorporate important prognostic factors. Since these models require complete covariate information on all patients, statisticians frequently resort to complete case analysis or to omission of an important covariate. A probability imputation ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780090707
更新日期:1990-07-01 00:00:00
abstract::Drop-out often occurs in clinical trials with multiple visits and drop-out is often informative in the sense that the population of patients who dropped out is different from the population of patients who completed the study. To handle data with informative drop-out, an intention-to-treat analysis, which evaluates tr...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1519
更新日期:2003-08-15 00:00:00
abstract::The development of drugs and biologicals whose mechanisms of action may extend beyond their target indications has led to a need to identify unexpected potential toxicities promptly even while blinded clinical trials are under way. One component of recently issued FDA rules regarding safety reporting requirements rais...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7129
更新日期:2017-01-15 00:00:00
abstract::We discuss some of the fundamental concepts underlying the development of frailty and random effects models in survival. One of these fundamental concepts was the idea of a frailty model where each subject has his or her own disposition to failure, their so-called frailty, additional to any effects we wish to quantify...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1259
更新日期:2002-11-15 00:00:00
abstract::Multi-type recurrent event data arise when two or more different kinds of events may occur repeatedly over a period of observation. The scientific objectives in such settings are often to describe features of the marginal processes and to study the association between the different types of events. Interval-censored m...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1936
更新日期:2005-03-15 00:00:00
abstract::Statistical methods for analyzing recurrent events have attracted significant attention. The majority of existing works consider situations in which subjects are observed over time periods and events of interest that occurred during the course of follow-up are recorded. In some applications, a subject may leave the st...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8042
更新日期:2019-04-15 00:00:00
abstract::Graphical methods based on the analysis of differences between log cumulative hazard functions are considered for a two-group semi-proportional hazard model which allows for interaction between treatments and covariates. Confidence procedures and test statistics that can be used to test for interaction and for main ef...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780111105
更新日期:1992-08-01 00:00:00
abstract::Systematic reviews often provide recommendations for further research. When meta-analyses are inconclusive, such recommendations typically argue for further studies to be conducted. However, the nature and amount of future research should depend on the nature and amount of the existing research. We propose a method ba...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5524
更新日期:2013-01-15 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::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::Proportional odds regression models for multinomial probabilities based on ordered categories have been generalized in two somewhat different directions. Models having scale as well as location parameters for adjustment of boundaries (on an unobservable, underlying continuum) between categories have been employed in t...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780141105
更新日期:1995-06-15 00:00:00
abstract::Variation in heart disease (HD) mortality rates across census tracts is greater than expected given binomial error and available explanatory variables. We extended an extra-binomial variation model for rates standardized by the direct method. The overdispersion parameter accounted for 36 per cent of the observed varia...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780091009
更新日期:1990-10-01 00:00:00
abstract::Evaluating treatment effects within different subsets of patients is a common practice in the analysis of individual randomized clinical trials. Such analyses are limited, however, by the number of patients available. Overviews, by providing evidence based on large numbers of patients, can be useful for overcoming the...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780060331
更新日期:1987-04-01 00:00:00
abstract::Arming the immune system against cancer has emerged as a powerful tool in oncology during recent years. Instead of poisoning a tumor or destroying it with radiation, therapeutic cancer vaccine, a type of cancer immunotherapy, unleashes the immune system to combat cancer. This indirect mechanism-of-action of vaccines p...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7157
更新日期:2017-02-20 00:00:00
abstract::Combining multiple markers can improve classification accuracy compared with using a single marker. In practice, covariates associated with markers or disease outcome can affect the performance of a biomarker or biomarker combination in the population. The covariate-adjusted receiver operating characteristic (ROC) cur...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7274
更新日期:2017-07-10 00:00:00
abstract::Recent studies have indicated variation in the infectivity beta of HIV among heterosexual couples. We represent this heterogeneity by modelling beta as a random variable. Using data on the number of contacts and seroconversion of couples, we fit the model by maximum-likelihood estimation with a beta distribution and a...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780080110
更新日期:1989-01-01 00:00:00
abstract::This paper describes statistical procedures for use in an experiment that compares two handwashing protocols. The evaluation of a handwashing protocol entails collection of the wash effluent. Colony counts for the effluent reflect the number of flora removed by the wash protocol. The analysis aims to formulate and est...
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.4780050412
更新日期:1986-07-01 00:00:00
abstract::Comparative calibration is the broad statistical methodology used to assess the calibration of a set of p instruments, each designed to measure the same characteristic, on a common group of individuals. Different from the usual calibration problem, the true underlying quantity measured is unobservable. Many authors ha...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19970830)16:16<1889::aid-s
更新日期:1997-08-30 00:00:00
abstract::Although transportation safety has greatly improved over the past 2 decades, motor vehicle crash injuries remain a leading cause of morbidity and mortality, particularly among young drivers. Driver errors and behaviors such as speeding and distraction contribute disproportionately to crashes among inexperienced novice...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7404
更新日期:2017-10-30 00:00:00
abstract::We consider a latent variable hazard model for clustered survival data where clusters are a random sample from an underlying population. We allow interactions between the random cluster effect and covariates. We use a maximum pseudo-likelihood estimator to estimate the mean hazard ratio parameters. We propose a bootst...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19970915)16:17<2009::aid-s
更新日期:1997-09-15 00:00:00
abstract::For robust detection performance, traditional control chart monitoring for biosurveillance is based on input data free of trends, day-of-week effects, and other systematic behaviour. Time series forecasting methods may be used to remove this behaviour by subtracting forecasts from observations to form residuals for al...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2835
更新日期:2007-09-30 00:00:00
abstract::The use of logistic models for independent binary data has relied first on asymptotic theory and later on exact distributions for small samples. However, the use of logistic models for dependent analysis based on exact analysis is not as common. Moreover, attention is usually given to one-stage clustering. In this pap...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4157
更新日期:2011-04-15 00:00:00
abstract::We consider bivariate survival times for heterogeneous populations, where heterogeneity induces deviations in an individual's risk of an event as well as associations between survival times. The heterogeneity is characterized by a bivariate frailty model. We measure the heterogeneity effects through deviations associa...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990430)18:8<907::aid-sim
更新日期:1999-04-30 00:00:00
abstract::In many epidemiological studies it is common to resort to regression models relating incidence of a disease and its risk factors. The main goal of this paper is to consider inference on such models with error-prone observations and variances of the measurement errors changing across observations. We suppose that the o...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3343
更新日期:2008-11-10 00:00:00
abstract::In this paper, we proposed a mechanistic breast cancer survival model based on the axillary lymph node chain structure, considering lymph nodes as a potential dissemination arrangement. We assume a naive breast cancer treatment protocol consisting of exposing patients first to a chemotherapy treatment on r intervals a...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5576
更新日期:2013-04-30 00:00:00
abstract::In the development of a new treatment in oncology, phase II trials play a key role. On the basis of the data obtained during phase II, it is decided whether the treatment should be studied further. Therefore, the decision to be made on the basis of the data of a phase II trial must be as accurate as possible. For ethi...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5585
更新日期:2012-12-30 00:00:00
abstract::This paper presents combinatorial (exact) methods that are useful in the analysis of disease cluster data obtained from small environments, such as buildings and neighbourhoods. Maxwell-Boltzmann and Fermi-Dirac occupancy models are compared in terms of appropriateness of representation of disease incidence patterns (...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780121906
更新日期:1993-10-01 00:00:00
abstract::The randomized clinical trial, LU19, conducted by the Medical Research Council Lung Cancer Working Party, was designed to compare ACE (doxorubicin, cyclophosphamide and etoposide) chemotherapy plus G-CSF (granulocyte colony-stimulating factor) at 2-week intervals versus ACE chemotherapy alone at standard 3-week interv...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章
doi:10.1002/1097-0258(20001015)19:19<2657::aid-sim557>
更新日期:2000-10-15 00:00:00
abstract::Patients who switch treatment groups in randomized clinical trials can cause problems in the interpretation of the results. Although the intention-to-treat method is recognized as being the most reliable analysis, it may result in an underestimate of the treatment effect if there have been patients who switch treatmen...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1002/(SICI)1097-0258(19961015)15:19<2069::AID-S
更新日期:1996-10-15 00:00:00