Translation and validation of Sinhala version of modified EORTC QLQ-OH15 in oral cancer patients who receive radiotherapy with or without chemotherapy in Sri Lanka.

Background: The recognition of patient-reported outcomes for oral cancer is important in improving patients' quality of life. The aim of this study was to translate and validate the modified Sinhala version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Oral Health Module (EORTC QLQ-OH15).

Methods: A cross-sectional study was conducted to validate the EORTC QLQ-OH15 that was modified after adding two questions to the original questionnaire. The two questions added were 'difficulty in opening the mouth wide' and 'trouble with talking' which affect oral health related quality of life (OHRQOL) of oral cancer patients receiving radiotherapy. The Sinhala translated modified EORTC QLQ-OH15 and already validated the core questionnaire EORTC QLQ-C30 were self-completed by 85 adult oral cancer patients who received initial anti-cancer treatment with radiotherapy with or without chemotherapy. Content and face validity were examined by an expert panel. Construct validity was confirmed by using factor analysis, multi-trait scaling analysis, and known group comparison. Reliability was assessed by internal consistency, test-retest reliability by Wilcoxon Signed Ranks Test and intra class correlation coefficient. Responsiveness to change was assessed.

Results: The majority of participants (58%) were aged 50-69 years and 84% were males. Nearly 32% had cancer of the anterior two thirds of the tongue. Of the sample, 66% received chemo radiotherapy. Thirteen items were included for the factor analysis. They were loaded for four factors. Three scales 'Eating problem', 'Gum and Speech problem' and 'Soreness' loaded with 5, 4 and 3 items respectively and single item 'teeth' to a one factor with the total variance explained was 72.74%. Mann-Whitney U tests for all three scales were statistically significant confirming the ability of the modified EORTC QLQ-OH15 to detect expected differences in OHRQOL in clinically different groups. Cronbach's alpha for all the scales were more than 0.8. Wilcoxon Matched Paired Sign Rank Test showed highly significant results (p < 0.05) for all three scales revealing high responsiveness.

Conclusions: The modified Sinhala version of the EORTC QLQ-OH15 is a valid, reliable tool that can be used to measure OHRQOL in oral cancer patients who receive radiotherapy with or without chemotherapy.