Abstract:
:Prevalence data provided by cancer registries are generally biased, since the patients that were diagnosed before the starting of the registry's activity cannot be included in the statistics. The relevance of this incompleteness bias is estimated in this paper. Incidence and relative survival are modelled as parametric functions describing a wide class of cancer diseases. Prevalence estimates are then computed considering different hypotheses on disease reversibility. The ratio between the prevalence observed by the registry and the total estimated prevalence is used as an index of completeness. An analytical evaluation of this ratio, as a function of the parameters characterizing the observational process and the biological behaviour of the disease, is given.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Capocaccia R,De Angelis Rdoi
10.1002/(sici)1097-0258(19970228)16:4<425::aid-simsubject
Has Abstractpub_date
1997-02-28 00:00:00pages
425-40issue
4eissn
0277-6715issn
1097-0258pii
10.1002/(SICI)1097-0258(19970228)16:4<425::AID-SIMjournal_volume
16pub_type
杂志文章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::Clinical trials often assess efficacy by comparing treatments on the basis of two or more event-time outcomes. In the case of cancer clinical trials, progression-free survival (PFS), which is the minimum of the time from randomization to progression or to death, summarizes the comparison of treatments on the hazards f...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6096
更新日期:2014-05-30 00:00:00
abstract::Three-arm trials including the experimental treatment, an active reference treatment and a placebo are recommended in the guidelines of the ICH and EMEA/CPMP as a useful approach to the assessment of assay sensitivity. Generally, the acceptable non-inferiority margin Δ has been defined as the maximum clinically irrele...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4099
更新日期:2011-02-10 00:00:00
abstract::Many split-mouth trials are characterized by the pairing of site-specific outcome and baseline data within each segment of a subject's mouth. However when the response variable of interest is binary, methods of statistical analysis for this design are not well developed. In this paper we present several analytic appro...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2782
更新日期:2007-08-15 00:00:00
abstract::A frequent objective in medical research is the investigation of differences in patient survival between several experimental treatments and one standard treatment. In order to assess these differences statistically, we have to apply adjustments for multiple comparisons to prevent an increased number of false-positive...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4403
更新日期:2012-01-13 00:00:00
abstract::Estimating the causal effect of quitting smoking on time to death or first myocardial infarction requires that one control for the differences in risk factors between individuals who elect to quite at each time t versus those who elect to continue smoking at time t. In this paper we examine the limitations of standard...
journal_title:Statistics in medicine
pub_type: 杂志文章,多中心研究
doi:10.1002/sim.4780121707
更新日期:1993-09-15 00:00:00
abstract::A new method is proposed for the surveillance of Down's syndrome among newborn. Despite the strong dependence of overall risk of Down's syndrome on maternal age, it has been suggested that an environmentally induced increase in risk may be additive over all maternal ages. The surveillance method introduced here is spe...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780120104
更新日期:1993-01-15 00:00:00
abstract::Clinical trials often assess therapeutic benefit on the basis of an event such as death or the diagnosis of disease. Usually, there are several additional longitudinal measures of clinical status which are collected to be used in the treatment comparison. This paper proposes a simple non-parametric test which combines...
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(19990615)18:11<1341::aid-s
更新日期:1999-06-15 00:00:00
abstract::Prediction performance of a risk scoring system needs to be carefully assessed before its adoption in clinical practice. Clinical preventive care often uses risk scores to screen asymptomatic population. The primary clinical interest is to predict the risk of having an event by a prespecified future time t0 . Accuracy...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7606
更新日期:2018-05-10 00:00:00
abstract::We propose a two-step procedure to personalize drug dosage over time under the framework of a log-linear mixed-effect model. We model patients' heterogeneity using subject-specific random effects, which are treated as the realizations of an unspecified stochastic process. We extend the conditional quadratic inference ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7016
更新日期:2016-10-30 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::This paper presents a procedure for obtaining short-term projections and lower bounds on the size of the acquired immunodeficiency syndrome (AIDS) epidemic. The method is similar to that proposed by Brookmeyer and Gail but adapted to the situation where individual dates of AIDS diagnosis are available. It gives result...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780081210
更新日期:1989-12-01 00:00:00
abstract::Vaccination in populations can have several kinds of effects. Establishing that vaccination produces population-level effects beyond the direct effects in the vaccinated individuals can have important consequences for public health policy. Formal methods have been developed for study designs and analysis that can esti...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7392
更新日期:2018-01-30 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::In this article we develop flexible regression models in two respects to evaluate the influence of the covariate variables on the mixed Poisson and continuous responses and to evaluate how the correlation between Poisson response and continuous response changes over time. A scenario for dealing with regression models ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2776
更新日期:2007-09-10 00:00:00
abstract::In many medical applications, combining information from multiple biomarkers could yield a better diagnosis than any single one on its own. When there is a lack of a gold standard, an algorithm of classifying subjects into the case and non-case status is necessary for combining multiple markers. The aim of this paper ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6780
更新日期:2016-04-15 00:00:00
abstract::Weak measurement of epidemiologic exposures is an impediment to appreciation of the effects of those exposures. This paper discusses two strategies to assess the true effects of weakly measured exposure. The first is to use external information about the extent of mismeasurement to adjust estimates of the effects of e...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780080904
更新日期:1989-09-01 00:00:00
abstract::Few methods are currently available for group sequential analysis of recurrent events data subject to a terminal event in the clinical trial setting. This research helps fill this gap by developing a completely nonparametric group sequential monitoring procedure for use with the two-sample Tayob and Murray statistic. ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8389
更新日期:2019-12-30 00:00:00
abstract::Writing the variance of the Mantel-Haenszel estimator under the null of homogeneity and inverting the corresponding test, we arrive at an improved confidence interval for the common risk difference in stratified 2 × 2 tables. This interval outperforms a variety of other intervals currently recommended in the literatur...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6122
更新日期:2014-07-30 00:00:00
abstract::We consider methods for selecting the joint specification of the mean and variance functions in statistical models for rates or counts. Based on analyses of diagnosis-specific hospital discharge rates in Michigan, we show that a Poisson model with an extra variance component for the systematic variation is superior to...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780100908
更新日期:1991-09-01 00:00:00
abstract::Crossover studies have been successfully conducted in the case of continuous responses. Existing procedures of analysis for ordinal responses, on the other hand, are rarely satisfactory unless strict, usually unrealistic, assumptions are made. In this paper we investigate a random effects model and show that the model...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780100611
更新日期:1991-06-01 00:00:00
abstract::We discuss a sample size calculation for a pair-matched case-control study to test for interaction between a specific exposure and a second risk factor. The second risk factor could be either binary or continuous. An algorithm for the calculation of sample size is suggested which is based on a logistic regression mode...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(20000415)19:7<923::aid-sim
更新日期:2000-04-15 00:00:00
abstract::In recent years, quality control charts have been increasingly applied in the healthcare environment, for example, to monitor surgical performance. Risk-adjusted cumulative (CUSUM) charts that utilize risk scores like the Parsonnet score to estimate the probability of death of a patient from an operation turn out to b...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8104
更新日期:2019-05-30 00:00:00
abstract::Cross-sectional designs are often used to monitor the proportion of infections and other post-surgical complications acquired in hospitals. However, conventional methods for estimating incidence proportions when applied to cross-sectional data may provide estimators that are highly biased, as cross-sectional designs t...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5608
更新日期:2013-06-30 00:00:00
abstract::Confidence intervals for a standardized effect are derived after stabilizing the variance of the Welch t-statistic. Simulation studies demonstrate the viability of the resulting intervals for a wide range of parameter values and sample sizes as small as five. The methodology is extended to the combination of results f...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2751
更新日期:2007-06-30 00:00:00
abstract::In this paper, we investigate the impact of time-invariant covariates when fitting transition mixed models. This is carried out by emphasizing on the role of baseline responses on the estimation process. Transition models are allowed for two cases of exogenous and endogenous baseline responses. We illustrate these con...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6270
更新日期:2014-11-30 00:00:00
abstract::Methods for dealing with tied event times in the Cox proportional hazards model are well developed. Also, the partial likelihood provides a natural way to handle covariates that change over time. However, ties between event times and the times that discrete time-varying covariates change have not been systematically s...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5683
更新日期:2013-06-30 00:00:00
abstract::Suppression of premature ventricular contractions (PVCs) is one of the goals of antiarrhythmic therapy. In a clinical trial, however, it may be difficult to distinguish antiarrhythmic drug effect from spontaneous variation in PVCs. We propose the application of linear regression to PVC histories to ascertain drug effe...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章
doi:10.1002/sim.4780020305
更新日期:1983-07-01 00:00:00
abstract::In this paper, we consider a full likelihood method to analyze continuous longitudinal responses with non-ignorable non-monotone missing data. We consider a transition probability model for the missingness mechanism. A first-order Markov dependence structure is assumed for both the missingness mechanism and observed d...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5359
更新日期:2012-12-10 00:00:00
abstract::In standard time-to-event or survival analysis, occurrence times of the event of interest are observed exactly or are right-censored, meaning that it is only known that the event occurred after the last observation time. There are numerous methods available for estimating the survival curve and for testing and estimat...
journal_title:Statistics in medicine
pub_type: 杂志文章,评审
doi:10.1002/(sici)1097-0258(19980130)17:2<219::aid-sim
更新日期:1998-01-30 00:00:00