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Hida E.,Japan National Institute of Public Health | Tango T.,Center for Medical Statistics
Journal of Biopharmaceutical Statistics | Year: 2013

The design of a three-arm trial including the experimental treatment, an active reference treatment, and a placebo is recommended as a useful approach to the assessment of noninferiority of the experimental treatment. The inclusion of the placebo arm enables the assessment of assay sensitivity and internal validation, in addition to testing the noninferiority of the experimental treatment to the reference. Generally, the acceptable noninferiority margin has been defined as the maximum clinically irrelevant difference between treatments in many two-arm noninferiority trials. However, many articles have considered a design in which the noninferiority margin is relatively defined as a prespecified fraction f of the unknown effect size of the reference treatment. Therefore, these methods cannot be applied to cases where the margin is defined as a prespecified difference between treatments. In this article, we propose score-based statistical procedures for a three-arm noninferiority trial with a prespecified margin for inference of the difference in the proportions of binary endpoints. In addition, we derive the approximate sample size and optimal allocation to minimize the total sample size and that of the placebo arm. A randomized controlled trial on major depressive disorder based on the difference in the proportions of remission is used to demonstrate our proposed method. © Taylor & Francis Group, LLC. Source


Tango T.,Center for Medical Statistics | Takahashi K.,Japan National Institute of Public Health
Statistics in Medicine | Year: 2012

Spatial scan statistics are widely used tools for detection of disease clusters. Especially, the circular spatial scan statistic proposed by Kulldorff (1997) has been utilized in a wide variety of epidemiological studies and disease surveillance. However, as it cannot detect noncircular, irregularly shaped clusters, many authors have proposed different spatial scan statistics, including the elliptic version of Kulldorff's scan statistic. The flexible spatial scan statistic proposed by Tango and Takahashi (2005) has also been used for detecting irregularly shaped clusters. However, this method sets a feasible limitation of a maximum of 30 nearest neighbors for searching candidate clusters because of heavy computational load. In this paper, we show a flexible spatial scan statistic implemented with a restricted likelihood ratio proposed by Tango (2008) to (1) eliminate the limitation of 30 nearest neighbors and (2) to have surprisingly much less computational time than the original flexible spatial scan statistic. As a side effect, it is shown to be able to detect clusters with any shape reasonably well as the relative risk of the cluster becomes large via Monte Carlo simulation. We illustrate the proposed spatial scan statistic with data on mortality from cerebrovascular disease in the Tokyo Metropolitan area, Japan. © 2012 John Wiley & Sons, Ltd. Source


Tango T.,Center for Medical Statistics
Biostatistics | Year: 2016

For the analysis of longitudinal or repeated measures data, generalized linear mixed-effects models provide a flexible and powerful tool to deal with heterogeneity among subject response profiles. However, the typical statistical design adopted in usual randomized controlled trials is an analysis of covariance type analysis using a pre-defined pair of "pre-post" data, in which pre-(baseline) data are used as a covariate for adjustment together with other covariates. Then, the major design issue is to calculate the sample size or the number of subjects allocated to each treatment group. In this paper, we propose a new repeated measures design and sample size calculations combined with generalized linear mixed-effects models that depend not only on the number of subjects but on the number of repeated measures before and after randomization per subject used for the analysis. The main advantages of the proposed design combined with the generalized linear mixed-effects models are (1) it can easily handle missing data by applying the likelihood-based ignorable analyses under the missing at random assumption and (2) it may lead to a reduction in sample size, compared with the simple pre-post design. The proposed designs and the sample size calculations are illustrated with real data arising from randomized controlled trials. © 2015 The Author 2015. Published by Oxford University Press. All rights reserved. Source


Matsuda A.,Center for Cancer Control and Information Services | Yamaoka K.,Teikyo University | Tango T.,Center for Medical Statistics
Experimental and Therapeutic Medicine | Year: 2012

For advanced non-small cell lung cancer (NSCLC) patients, the only treatment option is palliative therapy, with the aim of prolonging overall survival and improving disease-related symptoms and quality of life (QOL). However, to date, the effect of palliative care on QOL has not yet been thoroughly examined, and there has been no meta-analysis of previous studies reporting QOL outcomes following palliative care. We consider that it is important to evaluate not only survival and/or response rates, but also QOL in patients with advanced NSCLC receiving palliative chemotherapy. The aim of the present study was to obtain useful information for the selection of suitable chemotherapy regimens for advanced NSCLC patients, taking into consideration QOL, and to demonstrate the importance of QOL assessments during treatment. We performed a meta-analysis of QOL outcomes following treatments that compared carboplatin- to cisplatin-based chemotherapy. Trials were eligible for analysis if they had compared carboplatin- to cisplatin-based chemotherapy in advanced NSCLC patients who had not received prior chemotherapy, and if these studies reported QOL data. In the six trials eligible for analysis, 2,405 patients were randomized to receive cisplatin-based or carboplatin-based chemotherapy. The patients who received carboplatin-based chemotherapy had higher global QOL and less severe symptoms than those who received cisplatin-based chemotherapy. The survival rate, which was the primary outcome in clinical trials, and the response rate did not differ significantly between the two treatment groups. It is important to evaluate QOL in addition to the survival and response rates for advanced NSCLC, particularly when the treatment is palliative. Source


Saeki H.,Fujifilm Co. | Tango T.,Center for Medical Statistics | Wang J.,Chiba University
Journal of Biopharmaceutical Statistics | Year: 2016

In clinical investigations of diagnostic procedures to indicate noninferiority, efficacy is generally evaluated on the basis of results from independent multiple raters. For each subject, if two diagnostic procedures are performed and some units are evaluated, the difference in proportions for matched-pair data is correlated between the two diagnostic procedures and within the subject, i.e. the data are clustered. In this article, we propose a noninferiority test to infer the difference in the correlated proportions of clustered data between the two diagnostic procedures. The proposed noninferiority test was validated in a Monte Carlo simulation study. Empirical sizes of the noninferiority test were close to the nominal level. The proposed test is illustrated on data of aneurysm diagnostic procedures for patients with acute subarachnoid hemorrhage. © 2016 Taylor & Francis Source

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