RESUMO
PURPOSE: To validate the Sinhalese version of the EORTC QLQ-CR29 quality of life questionnaire for colorectal cancer. METHOD: We translated and pilot-tested (n=10) the questionnaire in Sri Lanka. We then assessed the reliability, factor structure and construct validity according to the EORTC guidelines. The testing was done in two tertiary care hospitals in Sri Lanka. RESULTS: Of 110 participants, 103 (93%) returned the questionnaire, and 15 out of 20 (75%) returned the repeat-test questionnaire within a period of two weeks. Out of the original four scales three had better reliability than the original scales: urinary frequency (Cronbach α - 0.82), blood and mucus in stools (α-0.85), defaecation problems (α-0.76). The body image scale showed low reliability (α - 0.33). However, when one of the 3 items in the scale was omitted, it showed sufficient reliability (α - 0.74). Factor analysis showed good reliability for overall assessment of the two item scale for stool frequency (α - 0.82) and six item scale for defaecation problems (α - 0.76). Correlations between the subscales of CR29 and C30 questionnaires were below 0.40, except for body image, which correlated moderately (r-0.44) with emotional functioning. This confirmed satisfactory overall construct validity Conclusion: The scales for urinary frequency, blood and mucus in stools and defaecation problems which were reliable and had good validity. Body image scale failed to show sufficient reliability with the three-item scale and we suggest omitting one of the items to improve the overall reliability of the questionnaire. Construct validity was comparable to published data.
