Zhang, Yifei Zang, Yong
Published in
Statistical methods in medical research
The delayed outcome issue is common in early phase dose-finding clinical trials. This problem becomes more intractable in phase I/II clinical trials because both toxicity and efficacy responses are subject to the delayed outcome issue. The existing methods applying for the phase I trials cannot be used directly for the phase I/II trial due to a lac...
Ditzhaus, Marc Dobler, Dennis Pauly, Markus
Published in
Statistical methods in medical research
Factorial survival designs with right-censored observations are commonly inferred by Cox regression and explained by means of hazard ratios. However, in case of non-proportional hazards, their interpretation can become cumbersome; especially for clinicians. We therefore offer an alternative: median survival times are used to estimate treatment and ...
Bucur, Ioan Gabriel Claassen, Tom Heskes, Tom
Published in
Statistical methods in medical research
The use of genetic variants as instrumental variables - an approach known as Mendelian randomization - is a popular epidemiological method for estimating the causal effect of an exposure (phenotype, biomarker, risk factor) on a disease or health-related outcome from observational data. Instrumental variables must satisfy strong, often untestable as...
Cao, Xuan Lee, Kyoungjae Huang, Qingling
Published in
Statistical methods in medical research
Parkinson's disease is a progressive, chronic, and neurodegenerative disorder that is primarily diagnosed by clinical examinations and magnetic resonance imaging (MRI). In this paper, we propose a Bayesian model to predict Parkinson's disease employing a functional MRI (fMRI) based radiomics approach. We consider a spike and slab prior for variable...
Bottai, Matteo Cilluffo, Giovanna
Published in
Statistical methods in medical research
Quantile regression is widely used to estimate conditional quantiles of an outcome variable of interest given covariates. This method can estimate one quantile at a time without imposing any constraints on the quantile process other than the linear combination of covariates and parameters specified by the regression model. While this is a flexible ...
Konietschke, Frank Schwab, Karima Pauly, Markus
Published in
Statistical methods in medical research
In many experiments and especially in translational and preclinical research, sample sizes are (very) small. In addition, data designs are often high dimensional, i.e. more dependent than independent replications of the trial are observed. The present paper discusses the applicability of max t-test-type statistics (multiple contrast tests) in high-...
Barrio, Irantzu Roca-Pardiñas, Javier Arostegui, Inmaculada
Published in
Statistical methods in medical research
The high impact of the lymph node ratio as a prognostic factor is widely established in colorectal cancer, and is being used as a categorized predictor variable in several studies. However, the cut-off points as well as the number of categories considered differ considerably in the literature. Motivated by the need to obtain the best categorization...
Lee, Chun Yin Lam, K F
Published in
Statistical methods in medical research
We apply a maximal likelihood ratio test for the presence of multiple change-points in the covariate effects based on the Cox regression model. The covariate effect is assumed to change smoothly at one or more unknown change-points. The number of change-points is inferred by a sequential approach. Confidence intervals for the regression and change-...
Chen, Yong Liang, Kung-Yee Tong, Pan Beaty, Terri H Barnes, Kathleen C Linda Kao, W H
Published in
Statistical methods in medical research
The case-control study design is one of the main tools for detecting associations between genetic markers and diseases. It is well known that population substructure can lead to spurious association between disease status and a genetic marker if the prevalence of disease and the marker allele frequency vary across subpopulations. In this paper, we ...
Scotina, Anthony D Zullo, Andrew R Smith, Robert J Gutman, Roee
Published in
Statistical methods in medical research
Randomized clinical trials are considered as the gold standard for estimating causal effects. Nevertheless, in studies that are aimed at examining adverse effects of interventions, randomized trials are often impractical because of ethical and financial considerations. In observational studies, matching on the generalized propensity scores was prop...
