Bias: A 30‐Year Review of Randomized Controlled Trials Published in Three Prosthodontic Journals

Abstract

Purpose Bias can occur in various phases of an investigation, and its control is an important measure of the validity of results for randomized controlled trials (RCTs). The purpose of this study is to determine if bias control in prosthodontic RCTs published from 2008 to 2017 improved over those published from 1988 to 1997. Materials and Methods MEDLINE was searched for RCTs in The International Journal of Prosthodontics, The Journal of Prosthetic Dentistry, and The Journal of Prosthodontics published from 2008 to 2017. Citations retrieved were included if the trial involved human subjects, included at least 2 treatment groups, and group assignment was by random allocation. Pilot and follow‐up studies were excluded. Included RCTs were evaluated on the basis of how control of potential sources of bias in trial methodology were reported. Three areas—control of bias at entry, control of bias in assessment of outcome, and control of bias after entry—were scored 1 or 0, based on whether method of randomization was explicitly reported, blinding was done, and all subjects were accounted for at the end of the study. Thus, the maximum quality score was 3 (good bias control) and the minimum 0 (poor bias control). Frequencies were calculated for each dimension of trial methodology, and overall scores were reported. Results were compared to those of RCTs published from 1988 to 1997 reported in a previous study. Results Ninety‐six RCTs published from 2008 to 2017 met the inclusion criteria and were reviewed. Method of randomization was explicit in 68% of RCTs, 50% reported blinding, and 85% accounted for all subjects; 32% scored the maximum 3 points for good bias control. In comparison, 62 RCTs published from 1988 to 1997 had frequencies of 47%, 40%, and 76% in the 3 areas examined, respectively; only 16% had maximum scores for good bias control. Conclusion Control of bias and overall quality scores have improved for RCTs published in the 3 studied prosthodontic journals.

Dental Research Waste in Design, Analysis, and Reporting: A Scoping Review

“…Saltaji et al (2017) reported that the implementation of randomization and blinding dental trials overall improved significantly over time (1955 to 2013). Improvements were also reported in orthodontics (Koletsi et al 2017) and over 30 y in prosthodontics (Dumbrigue, et al 2019a). Both design issues are integral to rigorous clinical trials and in reaching meaningful and trustworthy findings.…”

“…Despite improvements over time (Dumbrigue et al 2019a), specific issues included use of inappropriate and/or unclear methods of randomization and lack of blinding (Table 2). Adequacy of randomization ranged from 9% to 68% (Appendix Fig.…”