Importance: Spin, the inaccurate reporting of randomized clinical trials (RCTs) with results that are not statistically significant for the primary end point, distorts interpretation of results and leads to misinterpretation. However, the prevalence of spin and related factors in noninferiority cancer RCTs remains unclear.
Objective: To examine misleading reporting, or spin, and the associated factors in noninferiority cancer RCTs through a systematic review.
Data sources: A systematic search of the PubMed database was performed for articles published between January 1, 2010, and December 31, 2019, using the Cochrane Highly Sensitive Search Strategy.
Study selection: Two investigators independently selected studies using the inclusion criteria of noninferiority parallel-group RCTs aiming to confirm effects to cancer treatments published between January 1, 2010, and December 31, 2019, reporting results that were not statistically significant for the primary end points.
Data extraction and synthesis: Standardized data abstraction was used to extract information concerning the trial characteristics and spin based on a prespecified definition. The main investigator extracted the trial characteristics while both readers independently evaluated the spin. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed.
Main outcomes and measures: The main outcome was spin prevalence in any section of the report. Spin was defined as use of specific reporting strategies, from whatever motive, to highlight that the experimental treatment is beneficial, despite no statistically significant difference for the primary outcome, or to distract the reader from results that are not statistically significant. The associations (prevalence difference and odds ratios [ORs]) between spin and trial characteristics were also evaluated.
Results: The analysis included 52 of 2752 reports identified in the PubMed search. Spin was identified in 39 reports (75.0%; 95% CI, 61.6%-84.9%), including the abstract (34 reports [65.4%; 95% CI, 51.1%-76.9%]) and the main text (38 reports [73.1%; 95% CI, 59.7%-83.3%]). Univariate analysis found that the spin prevalence was higher in reports with data managers (prevalence difference, 27%; 95% CI, 1.1%-50.3%), reports without funding from for-profit sources (prevalence difference, 31.2%; 95% CI, 4.8%-53.8%), and reports of novel experimental treatments (prevalence difference, 37.5%; 95% CI, 5.8%-64.7%). Multivariable analysis found that novel experimental treatment (OR, 4.64; 95% CI, 0.98-22.02) and funding only from nonprofit sources only (OR, 5.20; 95% CI, 1.21-22.29) were associated with spin.
Conclusions and relevance: In this systematic review, most noninferiority RCTs reporting results that were not statistically significant for the primary end points showed distorted interpretation and inaccurate reporting. The novelty of an experimental treatment and funding only from nonprofit sources were associated with spin.