The domain structure of the EORTC QLQ-STO22 supported by Japanese validation data

This paper evaluates the scale structure of the EORTC QLQ-STO22 gastric cancer module using Japanese validation data. We additionally tested two single items regarding dumping syndrome. Of 246 patients who participated in phase II clinical trials of chemotherapy to treat advanced gastric cancer, we analyzed 206 who completed the pretreatment questionnaire. The factor analysis supported the scale structure hypothesized for the initial development phase conducted by the EORTC Quality of Life Group, not the alternations made in the final psychometric testing phase. The elicited scales exhibited high internal consistency and high clinical validity. Our data suggest that there is no need to examine the dumping syndrome items. This study revealed a slightly different scale structure of the QLQ-STO22 from that obtained in the European study. Extensive discussions with the EORTC Group are needed from both cross-cultural and clinical perspectives in order to establish a consensus on the various language versions of the QLQ-STO22.