Abstract
Quality of life （QOL） is now known to be one of the important prognostic factors in many clinical fields. Disease-specific quality of life is an important index as well as health related quality of life （HRQOL） to validate outcomes of medical treatments. The Orthognathic Quality of Life （OQLQ） index has been developed to measure QOL of dentofacial deformity. The aim of the present study was to develop a Japanese version of the OQLQ and examine its reliability and validity.
Materials & methods: With the permission of the OQLQ developer, the original English version of the OQLQ was translated into Japanese with a forward-backward translation method. A pilot study was carried out on a sample of 22 patients, and a validity study was done on a sample of 25 patients. The reliability was verified with Cronbach’s coefficient alpha and item-total correlation. The validity study was performed after confirming the reliability of the questionnaire, using the test-retest method. HRQOL was also measured to verify the validity of the questionnaire with SF-8, and correlation was verified with Spearman’s correlation coefficient. All of the patients who participated in this study were new patients who were diagnosed with dentofacial deformity.
Results: In the pilot study, the correlation coefficients of the item-total correlation score were −0.011 to 0.068. Some questions on oral function component showed a weak correlation, but Cronbach’s coefficient alpha of each component was 0.79-0.85, which revealed the reliability of the questionnaire. The paired t-test in the validity study showed no significant difference for most of the questions, confirming repeatability in the same patient and the validity of the questionnaire. Spearman’s correlation coefficient showed, for all four components of the OQLQ, moderate to strong correlation with some items of mental scales and MCS of SF-8.
Conclusion: We concluded that the Japanese version of the OQLQ we developed is a reliable and valid questionnaire.
