Abstract:
:In many chronic diseases, therapy aims to prevent or reduce the frequency of episodes of a disease manifestation, for example cardiac ischaemic episodes or epileptic seizures. Entry criteria for clinical trials typically include a minimum number of episodes within a baseline period, and regression to the mean should be anticipated. The distribution of the number of episodes at follow-up, the statistical power for treatment comparisons, and the difficulty of recruitment will depend on the entry criterion chosen. A gamma-Poisson mixture model is employed to describe the regression to the mean when the entry criterion and outcome measure are counts of discrete events. Sample size formulae which take account of the entry criterion are derived for comparison of mean number of events at follow-up and the proportion of patients with zero events at follow-up. Application of these formulae to screening data from the Asymptomatic Cardiac Ischemia Pilot (ACIP) Study is presented as an example.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
McMahon RP,Proschan M,Geller NL,Stone PH,Sopko Gdoi
10.1002/sim.4780130806subject
Has Abstractpub_date
1994-04-30 00:00:00pages
859-70issue
8eissn
0277-6715issn
1097-0258journal_volume
13pub_type
杂志文章abstract::The publication of Fisher's correspondence on statistics has shed new light on his views on randomization. Quotations from this correspondence and from other works of Fisher are used to illustrate the role of randomization in clinical trials. It is concluded that Fisher's views not only are coherent but, despite havin...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780130305
更新日期:1994-02-15 00:00:00
abstract::In longitudinal studies, missing observations occur commonly. It has been well known that biased results could be produced if missingness is not properly handled in the analysis. Authors have developed many methods with the focus on either incomplete response or missing covariate observations, but rarely on both. The ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5536
更新日期:2013-02-28 00:00:00
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::Prevention studies, as distinguished from studies investigating treatments for established disease, present some distinct challenges. Perhaps the most extensive experience with preventive agents is in the area of infectious diseases; vaccines have been extremely effective in preventing many such diseases. Vaccines hav...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1717
更新日期:2004-01-30 00:00:00
abstract::In psychiatry, clinicians use criteria sets from the Diagnostic and Statistical Manual of Mental Disorders to diagnose mental disorders. Most criteria sets have several symptom domains, and in order to be diagnosed, an individual must meet the minimum number of symptoms required by each domain. Some efforts are now fo...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8173
更新日期:2019-07-20 00:00:00
abstract::We consider counting process methods for analysing time-to-event data with multiple or recurrent outcomes, using the models developed by Anderson and Gill, Wei, Lin and Weissfeld and Prentice, Williams and Peterson. We compare the methods, and show how to implement them using popular statistical software programs. By ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19970930)16:18<2029::aid-s
更新日期:1997-09-30 00:00:00
abstract::Observational cohort studies often feature longitudinal data subject to irregular observation. Moreover, the timings of observations may be associated with the underlying disease process and must thus be accounted for when analysing the data. This paper suggests that multiple outputation, which consists of repeatedly ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6829
更新日期:2016-05-20 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::Biomedical studies often measure variables with error. Examples in the literature include investigation of the association between the change in some outcome variable (blood pressure, cholesterol level etc.) and a set of explanatory variables (age, smoking status etc.). Typically, one fits linear regression models to ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19981130)17:22<2597::aid-s
更新日期:1998-11-30 00:00:00
abstract::We propose a new, less costly, design to test the equivalence of digital versus analogue mammography in terms of sensitivity and specificity. Because breast cancer is a rare event among asymptomatic women, the sample size for testing equivalence of sensitivity is larger than that for testing equivalence of specificity...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19981015)17:19<2219::aid-s
更新日期:1998-10-15 00:00:00
abstract::In natural history studies of chronic disease, it is of interest to understand the evolution of key variables that measure aspects of disease progression. This is particularly true for immunological variables among persons infected with the human immunodeficiency virus (HIV). The natural time scale for such studies is...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780131103
更新日期:1994-06-15 00:00:00
abstract::Standard randomization-based tests of sharp null hypotheses in randomized clinical trials, that is, intent-to-treat analyses, are valid without extraneous assumptions, but generally can be appropriately powerful only with alternative hypotheses that involve treatment assignment having an effect on outcome. In the cont...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19980215)17:3<371::aid-sim
更新日期:1998-02-15 00:00:00
abstract::The design of clinical trials often requires knowledge of quantities such as between- and within subject variances about which only imprecise information exists. To provide assurance that the study has the desired power to detect a minimum clinically meaningful difference between treatment groups. Gould, Gould and Shi...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780142007
更新日期:1995-10-30 00:00:00
abstract::Age-period-cohort (APC) analysis is widely used in cancer epidemiology to model trends in cancer rates. We develop methods for comparative APC analysis of two independent cause-specific hazard rates assuming that an APC model holds for each one. We construct linear hypothesis tests to determine whether the two hazards...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3865
更新日期:2010-05-20 00:00:00
abstract::The stability-controlled quasi-experiment (SCQE) is an approach to study the effects of nonrandomized, newly adopted treatments. While covariate adjustment techniques rely on a "no unobserved confounding" assumption, SCQE imposes an assumption on the change in the average nontreatment outcome between successive cohort...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8717
更新日期:2020-12-10 00:00:00
abstract::Multilevel mixed effects survival models are used in the analysis of clustered survival data, such as repeated events, multicenter clinical trials, and individual participant data (IPD) meta-analyses, to investigate heterogeneity in baseline risk and covariate effects. In this paper, we extend parametric frailty model...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6191
更新日期:2014-09-28 00:00:00
abstract::Hierarchical regression analysis holds much promise for epidemiologic analysis, but has as yet seen limited application because of lack of easily used software and the relatively lengthy run times of preferred fitting methods (such as true maximum likelihood and Bayesian approaches). This paper compares three relative...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19970315)16:5<515::aid-sim
更新日期:1997-03-15 00:00:00
abstract::Methodology for the meta-analysis of individual patient data with survival end-points is proposed. Motivated by questions about the reliance on hazard ratios as summary measures of treatment effects, a parametric approach is considered and percentile ratios are introduced as an alternative to hazard ratios. The genera...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4086
更新日期:2010-12-20 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::In this paper, we define a modified version τ(b) of Kendall's tau to measure the association in a pair (X,Y) of random variables subject to fixed left censoring due to known lower detection limits. We provide a nonparametric estimator of τ(b) and investigate its asymptotic properties. We then assume an Archimedean cop...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4319
更新日期:2011-11-20 00:00:00
abstract::Ordinal data appear in a wide variety of scientific fields. These data are often analyzed using ordinal logistic regression models that assume proportional odds. When this assumption is not met, it may be possible to capture the lack of proportionality using a constrained structural relationship between the odds and t...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5689
更新日期:2013-06-15 00:00:00
abstract::The relationship between association and surrogacy has been the focus of much debate in the surrogate marker literature. Recently, the individual causal association (ICA) has been introduced as a metric of surrogacy in the causal inference framework, when both the surrogate and the true endpoint are normally distribut...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8698
更新日期:2020-11-20 00:00:00
abstract::Appropriate quantification of added usefulness offered by new markers included in risk prediction algorithms is a problem of active research and debate. Standard methods, including statistical significance and c statistic are useful but not sufficient. Net reclassification improvement (NRI) offers a simple intuitive w...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4085
更新日期:2011-01-15 00:00:00
abstract::Pooling biospecimens prior to performing lab assays can help reduce lab costs, preserve specimens, and reduce information loss when subject to a limit of detection. Because many biomarkers measured in epidemiological studies are positive and right-skewed, proper analysis of pooled specimens requires special methods. I...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6496
更新日期:2015-07-30 00:00:00
abstract::Two features commonly exhibited by randomized trials of health promotion interventions are cluster randomization and stratification. Ignoring correlations between individuals within clusters can lead to an inflated type I error rate and hence a P-value which overstates the significance of the result. This paper compar...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1256
更新日期:2002-12-30 00:00:00
abstract::Many studies have reported large variations in age- and sex-adjusted rates of hospitalizations across small geographic areas. These variations have often been attributed to differences in medical practice style which are not reflected in differences in health care outcomes. There is, however, another potentially impor...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1398
更新日期:2003-05-30 00:00:00
abstract::Many observational studies adopt what we call retrospective convenience sampling (RCS). With the sample size in each arm prespecified, RCS randomly selects subjects from the treatment-inclined subpopulation into the treatment arm and those from the control-inclined into the control arm. Samples in each arm are represe...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7808
更新日期:2018-05-20 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::Assessing and comparing the performance of correlated predictive scores are of current interest in precision medicine. Given the limitations of available theoretical approaches for assessing and comparing the predictive accuracy, numerical methods are highly desired which, however, have not been systematically develop...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8566
更新日期:2020-09-10 00:00:00
abstract::Although population-based molecular association studies are becoming increasingly popular, methodology for the meta-analysis of these studies has been neglected, particularly with regard to two issues: testing Hardy-Weinberg equilibrium (HWE), and pooling results in a manner that reflects a biological model of gene ef...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2010
更新日期:2005-05-15 00:00:00