The reporting quality of split-mouth trials in orthodontics according to CONSORT guidelines: 2015-19

To assess the reporting quality of split-mouth trials (SMTs) in orthodontic journals, and to identify factors associated with better reporting.

Seven leading orthodontic journals were hand searched for SMTs published during 2015-19. The CONSORT 2010 guideline and CONSORT for within-person trial (WPT) extension were used to assess the trial reporting quality (TRQ) and WPT-specific reporting quality (WRQ) of included SMTs, respectively. A binary score (0 or 1) was given to each item of the guidelines, and total scores were calculated for TRQ (score range, 0-32) and WRQ (score range, 0-15). Univariable and multivariable linear regression analyses were performed to identify factors associated with TRQ and WRQ.

A total of 42 SMTs were included. The mean overall scores for TRQ and WRQ were 16.8 [standard deviation (SD) 7.1] and 5.6 (SD 2.3), respectively. Only 11 SMTs (26.2%) presented the rationale for using a split-mouth design. Key methodological items including random sequence generation (22/42, 52.4%), allocation concealment (9/42, 21.4%), and blinding (20/42, 47.6%) were poorly reported. Only six SMTs (14.3%) used a paired method for sample size calculation, and half (21/42, 50.0%) considered the dependent nature of data in statistical analysis. In multivariable analyses, higher TRQ and WRQ were both significantly associated with journal, reported use of CONSORT and funding status.

The reporting quality of SMTs in orthodontics has much room for improvement. Joint efforts from relevant stakeholders are needed to improve the reporting quality of SMTs and reduce relevant avoidable research waste.