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A utility-based design for randomized comparative trials with ordinal outcomes and prognostic subgroups.

ABSTRACT: A design is proposed for randomized comparative trials with ordinal outcomes and prognostic subgroups. The design accounts for patient heterogeneity by allowing possibly different comparative conclusions within subgroups. The comparative testing criterion is based on utilities for the levels of the ordinal outcome and a Bayesian probability model. Designs based on two alternative models that include treatment-subgroup interactions are considered, the proportional odds model and a non-proportional odds model with a hierarchical prior that shrinks toward the proportional odds model. A third design that assumes homogeneity and ignores possible treatment-subgroup interactions also is considered. The three approaches are applied to construct group sequential designs for a trial of nutritional prehabilitation versus standard of care for esophageal cancer patients undergoing chemoradiation and surgery, including both untreated patients and salvage patients whose disease has recurred following previous therapy. A simulation study is presented that compares the three designs, including evaluation of within-subgroup type I and II error probabilities under a variety of scenarios including different combinations of treatment-subgroup interactions.

SUBMITTER: Murray TA

PROVIDER: S-EPMC6054910 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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A utility-based design for randomized comparative trials with ordinal outcomes and prognostic subgroups.

Murray Thomas A TA Yuan Ying Y Thall Peter F PF Elizondo Joan H JH Hofstetter Wayne L WL

Biometrics 20180122 3

A design is proposed for randomized comparative trials with ordinal outcomes and prognostic subgroups. The design accounts for patient heterogeneity by allowing possibly different comparative conclusions within subgroups. The comparative testing criterion is based on utilities for the levels of the ordinal outcome and a Bayesian probability model. Designs based on two alternative models that include treatment-subgroup interactions are considered, the proportional odds model and a non-proportiona ...[more]

PMID: 29359314

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Project description:Importance:Prognostic models may provide insight into clinical trial results and inform the clinical management of patients with BRAF V600-mutated metastatic melanoma. Objective:To identify subgroups with distinct survival outcomes based on clinical and genomic characteristics and to assess survival in identified prognostic subgroups across cohorts treated with dacarbazine, vemurafenib, or cobimetinib plus vemurafenib. Design, Setting, and Participants:This retrospective and exploratory recursive partitioning analysis (RPA) modeled associations between prespecified covariates and survival outcomes using pooled data from the BRIM-2, BRIM-3, BRIM-7, and coBRIM studies. Interventions:Dacarbazine, vemurafenib, or cobimetinib plus vemurafenib. Main Outcomes and Measures:Progression-free survival (PFS) and overall survival (OS), estimated using the Kaplan-Meier method. Results:The RPA included 1365 patients (783 men; 57.4%). Of these, 1032 (75.6%) were older than 65 years; 310 received cobimetinib plus vemurafenib; 717, vemurafenib alone; and 338, dacarbazine. Median follow-up was 14.1 months (interquartile range, 6.3-28.3 months). In the RPA that included all patients, baseline lactate dehydrogenase (LDH) level, Eastern Cooperative Oncology Group performance status (ECOG PS), presence or absence of liver metastases, and baseline sum of longest diameters of target lesions (SLDs) were significant prognostic factors for PFS: Median PFS was longest in patients with lower LDH (?2?×?upper limit of normal [ULN]), ECOG PS 0, and shorter SLD (?44 mm) (11.1 months; 95% CI, 7.0-18.4 months), and shortest in those with elevated LDH (>2?×?ULN) (3.5 months; 95% CI, 3.0-3.8 months). The subgroup with normal baseline LDH and no liver metastases had the longest median OS (22.7 months; 95% CI, 20.3-27.2 months). Similar PFS trends were observed when these prognostic subgroups were applied to the cobimetinib plus vemurafenib, vemurafenib alone, and dacarbazine cohorts. Baseline LDH, ECOG PS, and SLD were significant prognostic factors for OS: Median OS was longest in patients with normal LDH and shorter SLD (?45 mm) (27.2 months; 95% CI, 22.1-32.1 months) and shortest in those with elevated LDH (>2?×?ULN) (6.0 months; 95% CI, 5.3-6.8 months). Among patients in the most favorable subgroup (normal LDH and SLD ?45 mm), 3-year OS rates were 53.3% (95% CI, 39.5%-67.1%) in the cobimetinib plus vemurafenib cohort, 35.6% (95% CI, 27.4%-43.8%) in the vemurafenib cohort, and 35.6% (95% CI, 24.8%-46.4%) in the dacarbazine cohort. Among patients with available gene expression data, RPA identified gene signature as a significant prognostic factor for PFS in those with normal LDH; 3-year PFS rates were 21.9%, (95% CI, 15.4%-28.4%) and 8.8% (95% CI, 3.6%-14.1%) in immune and cell cycle signature, respectively. The RPA for OS did not identify gene signature as a significant factor. Conclusions and Relevance:Baseline LDH, ECOG PS, disease burden, and gene signature appear to be key determinants of survival outcomes in patients with BRAF V600-mutated metastatic melanoma treated with BRAF and/or MEK inhibitors. These results are consistent with survival benefits of cobimetinib plus vemurafenib over vemurafenib alone observed in the coBRIM study.

Project description:IntroductionRandomised controlled trials (RCTs) aim to assess the effect of one (or more) unproven health interventions relative to other reference interventions. RCTs sometimes use an ordinal outcome, which is an endpoint that comprises of multiple, monotonically ordered categories that are not necessarily separated by a quantifiable distance. Ordinal outcomes are appealing in clinical settings as specific disease states can represent meaningful categories that may be of clinical importance to researchers. Ordinal outcomes can also retain information and increase statistical power compared to dichotomised outcomes and can allow multiple clinical outcomes to be comprised in a single endpoint. Target parameters for ordinal outcomes in RCTs may vary depending on the nature of the research question, the modelling assumptions and the expertise of the data analyst. The aim of this scoping review is to systematically describe the use of ordinal outcomes in contemporary RCTs. Specifically, we aim to: [Formula: see text] Identify which target parameters are of interest in trials that use an ordinal outcome, and whether these parameters are explicitly defined. [Formula: see text] Describe how ordinal outcomes are analysed in RCTs to estimate a treatment effect. [Formula: see text] Describe whether RCTs that use an ordinal outcome adequately report key methodological aspects specific to the analysis of the ordinal outcome. Results from this review will outline the current state of practice of the use of ordinal outcomes in RCTs. Ways to improve the analysis and reporting of ordinal outcomes in RCTs will be discussed.Methods and analysisWe will review RCTs that are published in the top four medical journals (British Medical Journal, New England Journal of Medicine, The Lancet and the Journal of the American Medical Association) between 1 January 2012 and 31 July 2022 that use an ordinal outcome as either a primary or a secondary outcome. The review will identify articles through a PubMed-specific search strategy. Our review will adhere to guidelines for scoping reviews as described in the PRISMA-ScR checklist. The study characteristics and details of the study design and analysis, including the target parameter(s) and statistical methods used to analyse the ordinal outcome, will be extracted from eligible studies. The screening, review and data extraction will be conducted using Covidence, a web-based tool for managing systematic reviews. The data will be summarised using descriptive statistics.

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A utility-based design for randomized comparative trials with ordinal outcomes and prognostic subgroups.

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A utility-based design for randomized comparative trials with ordinal outcomes and prognostic subgroups.

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