Spin in the neurosurgical trauma literature: prevalence and associated factors - a systematic review protocol.

INTRODUCTION: Spin is defined as an inaccurate interpretation of results, intentionally or not, leading to equivocal conclusions and misdirecting readers to look at the data in an overly optimistic way. Previous studies have shown a high prevalence of spin in scientific papers and this systematic review aims to investigate the nature and prevalence of spin in the neurosurgical trauma literature. Any associated factors will be identified to guide future research practice recommendations. METHODS AND ANALYSIS: The Preferred Reporting Item for Systematic Reviews and Meta-Analyses recommendations will be followed. Randomised clinical trials (RCTs) that enrolled only patients with traumatic brain injury and investigated any type of intervention (surgical or non-surgical) will be eligible for inclusion. The MEDLINE/PubMed database will be searched for articles in English published in 15 top-ranked journals. Spin will be defined as (1) a focus on statistically significant results not based on the primary outcome; (2) interpreting statistically non-significant results for a superiority analysis of the primary outcome; (3) claiming or emphasising the beneficial effect of the treatment despite statistically non-significant results; (4) conclusion focused in the per-protocol or as-treated analysis instead of the intention-to-treat results; (5) incorrect statistical analysis; (6) republication of a significant secondary analysis without proper acknowledgement of the primary outcome analysis result. Traditional descriptive statistics will be used to present RCT characteristics. Standardised differences between the groups with or without spin will be calculated. The variables with a standardised difference equal or above 0.2 and 0.5 will be considered weakly and strongly associated with spin, respectively. ETHICS AND DISSEMINATION: This study will not involve primary data collection and patients will not be involved. TRIAL REGISTRATION NUMBER: 10.17605/OSF.IO/H3FGY.