Translation and Validation of Thai Versions of the Chronic Oral Mucosal Disease Questionnaire-15 and Oral Lichen Planus Symptom Severity Measure

Abstract

Objective: This study aimed to translate, culturally adapt, and validate the Thai versions of the Chronic Oral Mucosal Disease Questionnaire-15 (COMDQ-15) and Oral Lichen Planus Symptom Severity Measure (OLP-SSM), assessing quality of life and symptom severity in oral lichen planus (OLP). Methods: Following COSMIN guidelines, both original instruments were translated and culturally adapted into Thai. Psychometric evaluation, including structural validity, convergent and discriminative validity, and internal consistency, involved 203 Thai adults with OLP. Participants also completed psychological assessments (GAD-7, PHQ-9, PSS-10, B-IPQ), while clinicians rated disease activity of OLP using the OLP-DAS and OLP-IGA. Results: Structural validity supported the original four-factor COMDQ-15 and unidimensional OLP-SSM structures, consistent with international findings. Content validity was excellent (CVI ≥ 0.96). Convergent validity showed moderate-to-high correlations between COMDQ-15 scores and psychological measures, and between OLP-SSM scores and clinical disease activity. However, discriminative validity was limited in distinguishing symptom severity states, likely due to mild-to-moderate disease severity among participants. Internal consistency was robust (COMDQ-15 α = 0.922; OLP-SSM α = 0.778). Conclusion: The Thai COMDQ-15 and OLP-SSM are valid, reliable, and culturally appropriate tools for assessing symptom severity and quality of life in Thai OLP patients, enhancing clinical care and facilitating holistic disease management.