Study Objectives ‘Spin’, using reporting strategies to distort study results, can mislead readers of medical research. This study aimed to evaluate the prevalence and characteristics of ‘spin’ among randomised controlled trial (RCT) abstracts published in sleep medicine journals, and to identify factors associated with its presence and severity. Methods The search for RCTs published between 2010 and 2020 were conducted in seven reputable journals of sleep medicine. Abstracts of RCTs with statistically nonsignificant primary outcomes were included and analysed for ‘spin’, according to pre-determined ‘spin’ strategies. Chi-square tests or logistic regression analyses were performed to detect the association between characteristics of included abstracts and the presence and severity of ‘spin’. Results A total of 114 RCT abstracts were included in this study, of which 89 (78.1%) were identified as having at least one type of ‘spin’ strategy. Sixty-six abstracts (57.9%) had ‘spin’ in the Results section, 82 (71.9%) abstracts presented with ‘spin’ in the Conclusions section. The presence of ‘spin’ varied significantly among RCTs based on the different categories of research area (P=0.047) and the statistician involvement (P=0.045). Furthermore, research area (P=0.019) and funding status (P=0.033) were significant factors associated with the severity of ‘spin’. Conclusions The prevalence of ‘spin’ is high among RCT abstracts in sleep medicine. This raise the need for researchers, editors and other stakeholders to be aware of the issue of ‘spin’ and make joint efforts to eliminate it in future publications.

Randomized controlled trials (RCTs) are the gold standard for evaluating treatment efficacy in clinical research (Concato et al., 2000).Clinicians are more likely to make clinical decisions based on RCTs' results than observational studies, as RCTs can minimise known and unknown confounders while other study designs cannot. Therefore, researchers need to ensure that RCTs are conducted well and reported transparently.It is well-documented that the reporting and methodology of RCTs in oral implantology were poor (Cairo et al., 2012;. To guide the conduct and improve the