Comparison of EORTC quality of life core questionnaire (EORTC-QLQ-C30) and gastrointestinal quality of life index (GIQLI) in patients undergoing elective colorectal cancer resection

Background: EORTC-QLQ-C30 questionnaires and GIQLI questionnaires are used to evaluate post-operative quality of life (QoL). It was not clear whether results of both instruments are comparable. Therefore, the level of agreement between both QoL questionnaires was evaluated in patients undergoing elective colorectal cancer resection. Methods: Pre-operatively, 7 and 30 days after surgery 116 patients answered the EORTC-QLQ-C-30 and the GIQLI questionnaires in random order. Individual questions with similar content from each questionnaire were compared. Data for global QoL, physical (PF), emotional (EF) and social function ( SF) were linearly transformed to fit a scale from 0 to 100. Data from the two instruments were correlated and the level of agreement between them was calculated according to the method of Bland and Altman. Results: A total of 308 data sets [(pre-op. n=116; 7th pod n=101; 30th post-operative day ( pod) n=91)] were evaluated. Both instruments detected a reversible reduction of QoL after surgery and gave inferior results for patients with conditions known to impair QoL. EORTC-QLQ-C30 was more sensitive than GIQLI. The correlation between the two questionnaires for global QoL, PF and EF was good ( r= 0.53 - 0.66, p< 0.01), but no correlation for SF was detected ( r= - 0.44, p=0.44). Linearly transformed scores from the two instruments differed considerably from - 13 (95% CI - 51 to 24) points ( QoL) to 10 ( - 38 to 58) points ( PF). Conclusion: Although EORTC-QLQ-C30 scores and GIQLI scores from patients undergoing elective colorectal cancer surgery did correlate well, the level of agreement between the two instruments was quite low. Perioperative QoL data from the two instruments cannot be compared with each other.