Spin on adverse effects in abstracts of systematic reviews of orthodontic interventions: A cross-sectional study (Part 2)

Abstract Background. It is critical that abstracts of systematic reviews transparently report both the beneficial and adverse effects of interventions without misleading the readers. This cross-sectional study assessed whether adverse effects of interventions were reported or considered in abstracts of systematic reviews of orthodontic interventions and whether spin on adverse effects was identified when comparing the abstracts with what was sought and reported in these reviews. Methods. This cross-sectional study (part 2 of 2) used the same sample of 98 systematic reviews orthodontic interventions on human patients that was used in part 1. Eligible reviews were retrieved from the Cochrane Database of Systematic Reviews and the 5 leading orthodontic journals between August 1 2009 and July 31 2021. Prevalence proportions were sought for 3 outcomes as defined in the published protocol. Univariable logistic regression models were built to explore associations between the presence of spin in the abstract and predictors such as the journal, year, number of authors, conflict of interest reported, funding, and type of orthodontic intervention. Odd ratios (OR) 95% confidence intervals (95% CI) were used to quantify respectively the strength of associations and their precision. Results. The majority, 76.5% (75/98), of eligible reviews reported or considered (i.e., discussed, weighted etc.), potential adverse effects of orthodontic interventions in the abstract and the proportion of spin on adverse effects was 40.8% (40/98) in the abstract of these reviews. Misleading reporting was the predominant category of spin, i.e., 90% (36/40). The explorative analyses did not find an association between the presence of spin in the abstract and any of the predictors. Conclusion. End users of systematic reviews of orthodontic interventions have to be careful when interpreting the results on adverse effects in the abstracts of these reviews, because they could be jeopardized by uncertainties such as not being reported and misleading reporting as a result of spin. Editors, peer reviewers, researchers, and guideline developers have key responsibilities in tackling these problems. This is particularly important, because titles and abstracts are often the only read sections of papers in biomedicine.