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Measuring differential treatment benefit across marker specific subgroups: The choice of outcome scale.

ABSTRACT: Clinical and epidemiological studies of anticancer therapies increasingly seek to identify predictive biomarkers to obtain insights into variation in treatment benefit. For time to event endpoints, a predictive biomarker is typically assessed using the interaction between the biomarker and treatment in a proportional hazards model. Interactions are contrasts of summaries of outcomes and depend upon the choice of the outcome scale. In this paper, we investigate interaction contrasts under three scales - the natural logarithm of hazard ratio, the natural logarithm of survival probability, and survival probability at a pre-specified time. We illustrate that we can have a non-zero interaction on survival or logarithm of survival probability scales even when there is no interaction on the logarithm of hazard ratio scale. Since survival probabilities have clinically useful interpretation and are easier to convey to patients than hazard ratios, we recommend evaluating a predictive biomarker using survival probabilities. We provide empirical illustration of the three scales of interaction for evaluating a predictive biomarker using reconstructed data from a published melanoma study.

SUBMITTER: Satagopan JM

PROVIDER: S-EPMC5568905 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Measuring differential treatment benefit across marker specific subgroups: The choice of outcome scale.

Satagopan Jaya M JM Iasonos Alexia A

Contemporary clinical trials 20170222

Clinical and epidemiological studies of anticancer therapies increasingly seek to identify predictive biomarkers to obtain insights into variation in treatment benefit. For time to event endpoints, a predictive biomarker is typically assessed using the interaction between the biomarker and treatment in a proportional hazards model. Interactions are contrasts of summaries of outcomes and depend upon the choice of the outcome scale. In this paper, we investigate interaction contrasts under three s ...[more]

PMID: 28254404

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Project description:BackgroundThe aim of this study was to describe changes in patient-reported functional outcome measures (PROMs) comparing pre-treatment and 12 months after radical prostatectomy (RP), external beam radiation therapy (EBRT), brachytherapy and active surveillance (AS).MethodsMen enrolled from 2010 to 2019 in the South Australian Prostate Cancer Clinical Outcomes Collaborative registry a prospective clinical registry were studied. Urinary, bowel, and sexual functions were measured using Expanded Prostate Cancer Index Composite (EPIC-26) at baseline and 12 months post-treatment. Higher scores on the EPIC-26 indicate better function. Multivariable regression models were applied to compare differences in function and extent of bother by treatment.ResultsOf the 4926 eligible men, 57.0% underwent RP, 20.5% EBRT, 7.0% brachytherapy and 15.5% AS. While baseline urinary and bowel function varied little across treatment groups, sexual function differed greatly (adjusted mean scores: RP = 56.3, EBRT = 45.8, brachytherapy = 61.4, AS = 52.8; p < 0.001). Post-treatment urinary continence and sexual function declined in all treatment groups, with the greatest decline for sexual function after RP (adjusted mean score change - 28.9). After adjustment for baseline differences, post-treatment sexual function scores after EBRT (6.4; 95%CI, 0.9-12.0) and brachytherapy (17.4; 95%CI, 9.4-25.5) were higher than after RP. Likewise, urinary continence after EBRT (13.6; 95%CI, 9.0-18.2), brachytherapy (10.6; 95%CI, 3.9-17.3) and AS (10.6; 95%CI, 5.9-15.3) were higher than after RP. Conversely, EBRT was associated with lower bowel function (- 7.9; 95%CI, - 12.4 to - 3.5) than RP. EBRT and AS were associated with lower odds of sexual bother (OR 0.51; 95%CI, 0.29-0.89 and OR 0.60; 95%CI, 0.38-0.96, respectively), and EBRT with higher odds of bowel bother (OR 2.01; 95%CI, 1.23-3.29) compared with RP.ConclusionThe four common treatment approaches for prostate cancer were associated with different patterns of patient-reported functional outcomes, both pre- and 12 months post-treatment. However, after adjustment, RP was associated with a greater decline in urinary continence and sexual function than other treatments. This study underscores the importance of collecting baseline PROMs to interpret post-treatment functional outcomes.

Dataset Information

Measuring differential treatment benefit across marker specific subgroups: The choice of outcome scale.

Publications

Measuring differential treatment benefit across marker specific subgroups: The choice of outcome scale.

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