Development and validation of a short version of Chronic Oral Mucosal Disease Questionnaire (COMDQ-15).

Background The adoption of the Chronic Oral Mucosal Disease Questionnaire (COMDQ) into clinical practice has been low, despite its rigorous development process. A potential limitation of the COMDQ is the high response burden to patients. Therefore, the aim of the present study was to develop and validate a short version of the 26-item COMDQ. Methods The COMDQ data of 520 patients with chronic oral mucosal diseases were randomly divided into two subsamples. Descriptive item analysis and exploratory factor analysis (EFA) were performed using data from the first subsample for item reduction and development of the shortened COMDQ. The resulting short version was then validated using confirmatory factor analysis (CFA) on the other subsample. Internal consistency reliability of the short-form COMDQ was assessed using Cronbach's alpha. Criterion validity of this new scale was examined against its original version. Results Based upon item analysis, 11 items were dropped. EFA results on the remaining 15 items extracted four factors consistent with the original COMDQ, and CFA results displayed acceptable goodness-of-fit indices of this factor structure on different sample. The COMDQ-15 was then created. Cronbach's alpha of four subscale scores ranged from 0.7 to 0.91, indicating good internal consistency reliability of the COMDQ-15. Correlations between total and subscale scores of the COMDQ-15 and its parent scale were high, supporting good criterion validity of this shortened scale. Conclusion The COMDQ-15 is a brief, valid and reliable instrument that can give an overview of the patient's quality of life related to their chronic oral mucosal conditions.