(YNRF) Spin in the Neurosurgical Literature: Prevalence and Associated Factors – a Systematic Review

Introduction: Spin is defined as the inaccurate interpretation of results, intentionally or not, leading to equivocal conclusions and misleading the readers to look at the data in an optimistic way. Previous studies have shown a high prevalence of spin in scientific papers and our objective was to estabilish its frequency and associated factors in traumatic brain injury studies.

Methods: Randomized clinical trials (RCT) that enrolled only traumatic brain injury (TBI) patients and investigated any type of intervention (surgical or non-surgical) were eligible for inclusion. The MEDLINE / PubMed database was searched for articles in English published from 1960 to 2020 in fifteen top-ranked journals. Spin was defined as (1) a focus on statistically significant results without the primary outcome, as a within-group comparison, secondary outcomes, subgroup analyses, and modified population of analyses; (2) Interpreting statistically nonsignificant results for the primary outcomes as showing treatment equivalence or comparable effectiveness; (3) Claiming or emphasizing the beneficial effect of the treatment despite statistically nonsignificant results. (4) Conclusion focused in the per-protocol or as-treated analysis instead of the intention to treat (ITT) results; (5) Incorrect statistical analysis; (6) Republication without proper acknowledgment of the primary outcome analysis result.

Results: A total of 150 papers were included and 21% (n=32) had spin. The most common types of spin were 1 and 3. A neurosurgeon as the first author (p=0.02) and less number of patients (p=0.04) were statistically associated with the occurrence of the spin phenomenon, as well as the overall risk of bias using the Cochrane Risk of Bias Tool (p < 0.001). The presence of a statistician among the authors was not statistically associated with less spin (p=0.09).

Conclusion : This work suggests that spin is frequent in TBI RCTs even in top-ranked journals and readers must be cautious about the occurrence of spin, mainly in the conclusion.