Development of an Orthodontic Appliance Impact Questionnaire – Cross-sectional Validation

Abstract

Introduction The patient-reported outcome measures have been used extensively in the few last years. We could not identify any well- developed and validated measures in the literature that measure the impact of wearing orthodontic appliances on young people daily lives’ activities. Therefore, the main aim of the study was to assess the validity and reliability of a newly developed questionnaire that was designed to measure the impact of wearing orthodontic appliances. Methods This was a cross-sectional, quantitative study. Young people aged 11-18 years undergoing orthodontic treatment with a variety of fixed and removable appliances, including retainers, and at different stages of treatment were recruited from the Orthodontic Department, Charles Clifford Dental Hospital, Sheffield, United Kingdom. The young people were asked to complete the questionnaire at one of their routine review appointments. To evaluate the reliability of the measure, patients were asked whether they are happy to fill the questionnaire again. Printed questionnaires were sent to patients who were willing to complete the measure a second time. Validation of the response format, items and assessment of differential item functioning were achieved using item response theory (IRT) Rasch model. The construct validity was assessed using Spearman’s rank correlation. Internal consistency/reliability was examined using Cronbach’s alpha. The intraclass correlation coefficient (ICC) was used to calculate test-retest reliability. Results A hundred and eighty-one adolescents aged 11-18 years were recruited from Charles Clifford Dental Hospital, Orthodontic Department. There were 117 (65%) females and 64 males (35%), with a mean age of 14.7 years (SD 1.5). Participants were wearing a wide variation in the type 1 of orthodontic appliances including, fixed appliances, twin blocks, lower lingual and transpalatal arches, quadhelix, face masks and retainers. A group of 129 patients agreed to complete the questionnaire for a second time to assess the reliability of the measure. Only 41 participants (31.8% of the sample) managed to send the questionnaire back. Statistical analysis: The initial measure showed misfit to the Rasch model. Ten items of the original 31 items had disordered thresholds, indicating that the response categories were not functioning as expected, and therefore they were removed. The 5-point scale was changed to a 3-point scale by combining the 2nd and 3rd categories together and the 4th and 5th categories together. None of the participants demonstrated misfit to the model. The score of the construct validity was high (ρ=0.480). The internal consistency and reliability of the measure were high as well (Cronbach’s alpha score = 0.827). The intraclass correlation coefficient result was also high giving a score of 0.845 (95%CI 0.727 to 0.915). Conclusion The newly developed OHRQoL measure has high construct validity, reliability and internal consistency. It would be beneficial to test the validity and reliability of this measure in longitudinal studies and in different other hospitals and private practices.