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A case study on the reporting of effect size estimates in breast cancer trials

Date and Location




Saturday 21 September 2013 - 10:30 - 12:00


Presenting author and contact person

Presenting author

Melina Willson

Contact person

Melina Willson
Abstract text
Background: Guidance on trial reporting from the CONSORT statement outlines that primary and secondary outcomes should be presented with estimated effect sizes and range (item 17; [1]). In oncology trial reports, time-to-event outcomes are commonly reported in the form of survival curves. When pooling time-to-event data for systematic reviews, the Hazard Ratio (HR) from survival curves is the most appropriate way to express the results [2]. Objectives: To conduct a preliminary assessment on whether trial reports comply with CONSORT by providing the appropriate effect estimate and range for each time-to-event outcome. Methods: A Cochrane review update on Taxane-containing regimens for metastatic breast cancer was used as a test case. For each included study that had a full-text publication, details on the time-to-event outcome reported and the presence or absence of (i) a survival curve (ii) a P-value and (iii) HR, median survival time or risk ratio and associated Confidence Interval (CI) were extracted. Results: Twenty-four trial publications were included and publication dates ranged from 1995 to 2011. Nearly all trial reports (23 out of 24) provided survival curves for overall survival and time-to-progression or time-to-failure and P-values, and reported one effect estimate (i.e. either median survival times, risk ratios or HRs). The ranges for median survival times or risk ratios were absent in 6 out of 24 trial reports. Also, 6 out of 24 trials reported HRs and CIs, and this was observed in trials published in the early 2000s and 2011. Conclusions: This case study showed that effect size estimates for time-to-event outcomes were consistently reported, suggesting compliance with CONSORT. However, only a small number of trials (6/24) reported the HRs and CIs from the survival curves. The lack of reporting relevant effect sizes, such as HRs, for time-to-event outcomes may have implications when undertaking meta-analyses.