Study design and primary outcome in randomized controlled trials in periodontology. A systematic review

The aim of this review is to assess study design and risk of bias related to primary outcome in recently published randomized controlled trials (RCTs) in periodontology.

An electronic (Medline, EMBASE and Cochrane library) and a manual search were completed to detect RCTs in humans, with an outcome in the field of periodontology and published in English from January 2018 up to March 2020.

Data extraction of 318 publications meeting the inclusion criteria was performed by two reviewers. Most studies adopted a parallel-group superiority design in a university setting. Overall, 54% of papers reported the primary outcome and relative sample size calculation, while only 37% also included reproducibility estimates relative to the primary outcome. Papers published in journals with higher impact factors had better compliance with primary outcome reporting and lower overall risk of bias scores.

Improvements in the quality of RCTs in periodontology are still needed. The importance of defining a clinically relevant study primary outcome and building the study around it needs to be emphasized. Furthermore, RCTs in periodontology could consider, when appropriate, some of the study design options which facilitate application of the principles of personalized medicine.