Development of a core outcome set for use in routine orthodontic clinical trials

Introduction: A diverse range of outcomes is used in orthodontic research with a focus on measuring outcomes important to clinicians and little consistency in outcome selection and measurement. We aimed to develop a core outcome set for use in clinical trials of orthodontic treatment not involving cleft or orthognathic patient groups. Methods: A list of outcomes measured in previous orthodontic research was identified through a scoping literature review. Additional outcomes of importance to patients were obtained using qualitative interviews and focus groups with adolescents aged 10-16 years. Rating of outcomes was carried out in a 2-round electronic Delphi process involving health care professionals and patients using a 9-point scale. A face-to-face meeting was subsequently held with stakeholders to discuss the results before refining the core outcome set. Results: After triangulation, a final list of 34 outcomes grouped under 10 domains was obtained for rating in the e-Delphi surveys. Fifteen outcomes were voted in after the second Delphi round involving 274 participants with a further outcome being included after the consensus meeting. These were subsequently refined into a final set of 7 core outcomes, including the impact of self-perceived esthetics, alignment and/or occlusion, skeletal relationship, stability, patient-related adherence, breakages, and adverse effects on teeth or teeth-supporting structures. Conclusions: A bespoke orthodontic core outcome set encompassing both clinician- and patientfocused outcomes was developed. Incorporating this is the first step into providing a more holistic assessment of the impact of treatment while allowing for meaningful comparisons and synthesis of results from individual trials.