(ChemotherapyAdvisor) – A high proportion of published studies of phase 3 randomized clinical trials for women with breast cancer demonstrate bias when reporting outcomes with negative primary end points and, when end points are positive, toxicity is under-reported, the first study to investigate this association reported in Annals of Oncology, published online January 10, 2013.
In one-third of trials failing to show a statistically significant benefit for the study treatment, the studies focused on other, less important outcomes in an attempt to put a positive interpretive “spin” on the results, noted Ian Tannock, MD, PhD, Division of Medical Oncology and Hematology at the Princess Margaret Hospital, Toronto, Ontario, Canada, and colleagues.
And, in two-thirds of the reports, only 32% of trials that showed a significant benefit for the study treatment reported frequency of grade 3 or 4 toxicities in the abstract.
“Better and more accurate reporting is urgently needed,” stated Dr. Tannock. “Journal editors and reviewers, who give their expertise on the topic, are very important in ensuring this happens. However, readers also need to critically appraise reports in order to detect potential bias. We believe guidelines are necessary to improve the reporting of both efficacy and toxicity.”
A PUBMED search of randomized phase 3 trials conducted from January 1995 to August 2011 found 164 that were eligible for inclusion in the analysis.
The investigators defined bias as “inappropriate reporting of the primary end point and toxicity, with emphasis on reporting of these outcomes in the abstract” and spin as “the use of words in the concluding statement of the abstract to suggest that a trial with a negative primary end point was positive based on some apparent benefit shown in one or more secondary end points.”
They found that 54 (33%) trials showed bias in reporting of the primary end point “and used spin in attempts to conceal that bias,” the authors wrote. In 92 trials with a negative primary end point, 59% used secondary end points to suggest benefit.
Biased reporting of adverse events occurred in 110 papers (67%), with toxicities more likely to be under-reported if the primary end point was positive.
The source of funding for trials (industry or academic) was not associated with bias or spin in the reporting of results and toxicities, they concluded, and added that “trial registration does not necessarily remove bias in reporting outcomes, although it does make it easier to detect.”