Analyzing Spin in Abstracts of Orthopaedic Randomized Controlled Trials with Statistically Insignificant Primary Endpoints

Abstract

Purpose: Our primary aim of our study is to evaluate the prevalence of spin among abstracts in orthopaedic randomized controlled trials (RCTs) with nonsignificant primary endpoints.

Methods: This study was conducted in accordance with a previously written protocol publicly available via the Open Science Framework. PubMed (which includes Medline) was searched for RCTs in orthopaedic surgery. The articles that were identified were then uploaded to Rayyan, and the abstracts were screened for inclusion. To be included, a trial had to have randomized the patients for intervention, statistically compare multiple groups, and had a primary endpoint that was not significant. Odds ratios and summary statistics (frequencies and proportions) were then calculated for spin in the abstracts.

Results: Of the 780 articles retrieved from our search string, 250 articles met the inclusion criteria. Analysis resulted in 112/250 (44.80%; [95% CI, 38.64-50.96]) RCTs that containing spin within the abstract. Of the 112 RCTs, 52 (46.43%; [95% CI, 37.19-55.66]) had spin in the results, and 89 (79.46%; [95% CI, 71.98-86.95]) had spin in the conclusion of the abstract. The Journal of Bone and Joint Surgery was found to have the highest prevalence of spin (21/37, 56.76% [95% CI, 40.79%-72.72%]) while Arthroscopy: The Journal of Arthroscopic & Related Surgery had the lowest prevalence of spin (5/15, 33.33% [95% CI, 9.48%-57.19%]). No correlation was found between industry funding and increased odds of spin in the abstract (uOR, 1.10; 95% CI, 0.45-2.63). Discrepancies for our primary endpoint, prevalence of spin among abstracts, were analyzed with Gwet's AC1 inter-rater statistic and found to be 81% [95% CI, 0.75-0.87].

Conclusion: Spin was found in 44.8% of the abstracts within our sample of orthopaedic RCTs. Nonsignificant primary data were often represented to seem significant, many orthopaedic RCTs did not indicate primary endpoints, and orthopaedic RCTs infrequently reported trial registration.

Keywords: bias; orthopaedics; randomized controlled trials; selective reporting bias; spin.