artbin: Extended sample size for randomized trials with binary outcomes.

We describe the command artbin, which offers various new facilities for the calculation of sample size for binary outcome variables that are not otherwise available in Stata. While artbin has been available since 2004, it has not been previously described in the Stata Journal. artbin has been recently updated to include new options for different statistical tests, methods and study designs, improved syntax, and better handling of noninferiority trials. In this article, we describe the updated version of artbin and detail the various formulas used within artbin in different settings.

Real-World Evidence Utilization in Clinical Development Reflected by US Product Labeling: Statistical Review.

The US Food and Drug Administration (FDA) has shown scientific discretion in interpreting the substantial evidence requirement for the approval of new drugs with its considerations on the use of single controlled or uncontrolled trials (Federal Food, Drug, and Cosmetic Act § 505(d), 21 USC 355(d), 1962). With the passage of the 21st Centuries Cures Act (21st Century Cures-patients. House, Energy and Commerce Committee, Washington, DC, 2019 available at: https://energycommerce.house.gov/sites/republicans.energycommerce.house.gov/files/analysis/21stCenturyCures/20140516PatientsWhitePaper.pdf ), the FDA is mandated to expand the role of real-world evidence (RWE) in support of drug approval. This mandate further broadens the scope of scientific discretion to include data collected outside clinical trials. We summarize the agency's past acceptance of real-world data (RWD) sources for supporting drug approval in new indications which have been reflected in US labels. In our summary, we focus on the type of RWD and statistical methodologies presented in these labels. Furthermore, two labels were selected for in-depth assessment of the RWE presented in these labels. Through these examples, we demonstrate the issues that can be raised in data collection that could affect interpretation. In addition, a brief discussion of statistical methods that can be used to incorporate RWE to clinical development is presented.

Development and validation of the Detail and Flexibility Questionnaire (DFlex) in eating disorders.

Whilst neuropsychological testing provides the most accurate profile of cognitive functioning, the time consuming nature of individual assessment deems it impossible for many research and clinical settings. This paper presents the development and validation of the Detail and Flexibility Questionnaire (DFlex), a 24-item self-report scale measuring two aspects of neurocognitive functioning; cognitive rigidity (difficulty with set-shifting/flexibility) and attention to detail (weak coherence). Exploratory factor analysis extracted two subscales, further confirmed and refined by item response analysis. Both subscales showed high internal reliability, construct validity (as compared to relevant subscales of the Autistic-Spectrum Quotient) and strong discriminant validity with large effect sizes found between both lifetime eating disorder and healthy control groups, and between current and recovered anorexia nervosa. We suggest using the cognitive rigidity and attention to detail subscales independently to give a rough approximation of these two aspects of cognitive style as they manifest in the context of everyday life.

Designs for clinical trials with time-to-event outcomes based on stopping guidelines for lack of benefit.

BACKGROUND: The pace of novel medical treatments and approaches to therapy has accelerated in recent years. Unfortunately, many potential therapeutic advances do not fulfil their promise when subjected to randomized controlled trials. It is therefore highly desirable to speed up the process of evaluating new treatment options, particularly in phase II and phase III trials. To help realize such an aim, in 2003, Royston and colleagues proposed a class of multi-arm, two-stage trial designs intended to eliminate poorly performing contenders at a first stage (point in time). Only treatments showing a predefined degree of advantage against a control treatment were allowed through to a second stage. Arms that survived the first-stage comparison on an intermediate outcome measure entered a second stage of patient accrual, culminating in comparisons against control on the definitive outcome measure. The intermediate outcome is typically on the causal pathway to the definitive outcome (i.e. the features that cause an intermediate event also tend to cause a definitive event), an example in cancer being progression-free and overall survival. Although the 2003 paper alluded to multi-arm trials, most of the essential design features concerned only two-arm trials. Here, we extend the two-arm designs to allow an arbitrary number of stages, thereby increasing flexibility by building in several 'looks' at the accumulating data. Such trials can terminate at any of the intermediate stages or the final stage. METHODS: We describe the trial design and the mathematics required to obtain the timing of the 'looks' and the overall significance level and power of the design. We support our results by extensive simulation studies. As an example, we discuss the design of the STAMPEDE trial in prostate cancer. RESULTS: The mathematical results on significance level and power are confirmed by the computer simulations. Our approach compares favourably with methodology based on beta spending functions and on monitoring only a primary outcome measure for lack of benefit of the new treatment. CONCLUSIONS: The new designs are practical and are supported by theory. They hold considerable promise for speeding up the evaluation of new treatments in phase II and III trials.

Speeding up the evaluation of new agents in cancer.

Despite both the increase in basic biologic knowledge and the fact that many new agents have reached various stages of development during the last 10 years, the number of new treatments that have been approved for patients has not increased as expected. We propose the multi-arm, multi-stage trial design as a way to evaluate treatments faster and more efficiently than current standard trial designs. By using intermediate outcomes and testing a number of new agents (and combinations) simultaneously, the new design requires fewer patients. Three trials using this methodology are presented.