We thank Saltaji, Flores-Mir, and Major for their comments regarding our article pertaining to clinical trial registration in oral health journals (Smaïl-Faugeron et al. 2015). The three authors concur with our primary findings and our call for improvements in the registration of trials, but they raised 2 points.
Regarding the first point, because we focused on randomized controlled trials (RCTs), it was logical for us to plan the assessment of the risk of selection bias, using the two relevant items of the Cochrane Collaboration Risk of Bias tool (random sequence generation and allocation concealment). Previous studies showed that only 22 to 30% of RCTs in dental journals could be considered to be at low risk of selection bias. In fact, the quality of reporting was frequently insufficient for a judgment to be made, or the random sequence generation or the allocation concealment was indeed inadequate (Hurst 2011; Koletsi et al. 2012). We found similar results, since the risk of selection bias was unclear for 80% of the selected RCTs. Saltaji, Flores-Mir, and Major are correct to note that trial registration allows peer-reviewers and meta-analysts to assess publication and selective outcome reporting biases. We acknowledge that, for registered trials, we could have assessed the extent of selective reporting bias but it was not our objective in this study. However, it would be interesting to compare published articles with the registered trial record and thus to assess the risk of selective outcome reporting bias in oral health RCTs, as has been done in other medical fields (Mathieu et al. 2009; Dwan et al. 2013).
Regarding the second point, we assessed the journal Web sites in December 2013, and, as discussed in our manuscript, this may not have reflected the author instructions at the time that articles selected in our study sample were submitted. It is a limitation to the comparison between journals according to editorial policies. The number of RCTs in the 5 journals requiring or recommending trial registration may be higher than that at the time they were submitted. However, it would have been impractical to document the dates of submission of the 150 selected RCTs in these 5 journals and to compare them to the specific date after which regulation for clinical trial registration was required by each of these journals. More importantly, this limitation does not affect our primary findings, with only 23% of RCTs registered overall. All oral health journals should require trial registration and include the reporting of a trial identification number in the author guidelines (Smaïl-Faugeron et al. 2015).
Footnotes
The authors received no financial support and declare no potential conflicts of interest with respect to the authorship and/or publication of this article.
References
- Dwan K, Gamble C, Williamson PR, Kirkham JJ. 2013. Systematic review of the empirical evidence of study publication bias and outcome reporting bias – an updated review. PLoS One. 8(7):e66844. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hurst D. 2011. Quality of reporting randomised controlled trials in major dental journals suboptimal. Evid Based Dent. 12(2):52-53. [DOI] [PubMed] [Google Scholar]
- Koletsi D, Pandis N, Polychronopoulou A, Eliades T. 2012. What’s in a title? An assessment of whether randomized controlled trial in a title means that it is one. Am J Orthod Dentofacial Orthop. 141(6):679-685. [DOI] [PubMed] [Google Scholar]
- Mathieu S, Boutron I, Moher D, Altman DG, Ravaud P. 2009. Comparison of registered and published primary outcomes in randomized controlled trials. J Am Med Assoc. 302(9):977-984. [DOI] [PubMed] [Google Scholar]
- Smail-Faugeron V, Esposito M. 2014. Should all clinical trials of oral health be registered? Eur J Oral Implantol. 7(4):327-328. [PubMed] [Google Scholar]
- Smaïl-Faugeron V, Fron-Chabouis H, Durieux P. 2015. Clinical trial registration in oral health journals. J Dent Res. 94(3 Suppl):8–13. [DOI] [PMC free article] [PubMed] [Google Scholar]