Adherence to Registration and Selective Outcome Reporting in Randomized Clinical Trials Published in Endodontic Journals Over the Past 5 Years: A Meta-Research Study

Introduction: Prospective registration of randomized clinical trials (RCTs) is highly recommended to ensure research transparency and prevent selective outcome reporting (SOR). This study aimed to evaluate the adherence to registration and the presence of SOR in RCTs published in endodontic journals over the past 5 years.

Methods: Electronic searches were conducted in PubMed and the libraries of the Journal of Endodontics, International Endodontic Journal, European Endodontic Journal, and Australian Endodontic Journal. Two reviewers were involved in the study selection and evaluation. Publications were assessed for key methodological aspects, including the presence and timing of trial registration. RCT registries were examined to identify discrepancies between publication and registered protocols and the presence of SOR. Logistic regression was used to explore the effect of study variables on registration practices and SOR.

Results: Of the 144 RCTs included, 104 (72.2%) were registered. Among those registered, only 19 (18.3%) adhered to prospective registration. Registration practice increased by 53% per year (OR 1.53; 95% CI: 1.34-2.08; P < .01). Discrepancies between publication and protocol were identified in 55.8% of studies, primarily related to sample size (33.7%). SOR was identified in 41 trials (39.4%), mainly due to discrepancies in the outcome time frame (18.3%). Studies evaluating multiple outcomes had 4.95 times higher odds of exhibiting SOR (OR 4.95; 95% CI: 1.63-12.95; P < .01). Furthermore, studies that were registered retrospectively or exhibited discrepancies between publication and protocol accounted for 6.10 times (OR 6.10; 95% CI: 1.81-18.96; P = .03) and 5.61 times (OR 5.61; 95% CI: 2.93-16.58; P < .01) higher odds of exhibiting SOR, respectively.

Conclusions: RCTs published in endodontic journals over the past 5 years presented low adherence to prospective trial registration and a high prevalence of SOR.