Precision medicine optimizes treatment for the individual rather than the average patient typically described in clinical trials. Unique factors such as genetics, anatomy, and past environmental exposures influence how each patient responds to treatment. This phenomenon is known as heterogeneity of treatment effects or HTE. It is not known how often HTE is assessed in the orthodontic literature. The aim of this study was to investigate HTE reporting and the characteristics of recent trials that have analyzed HTE in major orthodontic specialty journals.

Randomized clinical trials (RCTs) published in European Journal of Orthodontics, American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, Korean Journal of Orthodontics, and Orthodontics and Craniofacial Research from 2012 – 2016 were identified and searched for HTE results. Characteristics of these RCTs were described.

Of the 175 RCTs identified, 20 (11.43%) met the HTE inclusion criteria. Studies with and without HTE reporting were similar in many aspects, such as number of subjects enrolled, but differed in study design and number of hypothesis tests performed with fewer tests in RCTs reporting HTE (median: 10.5 tests) than not (median: 24 tests).

HTE keyword terminology could be valuable to incorporate as momentum builds surrounding precision health and personalized treatment. When terms such as ‘subgroup’ or ‘interaction’ are used, readers and reviewers are alerted that differences in treatment response among patient subgroups have been assessed. Investigators have the opportunity to increase the impact of their work by evaluating whether certain patient characteristics cause HTE.