Development and Validation of the Korean Version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire for Patients with Non-muscle Invasive Bladder Cancer: EORTC QLQ-NMIBC24

Park, Jinsung; Shin, Dong Wook; Kim, Tae-Hwan; Jung, Seung Il; Nam, Jong Kil; Park, Seung Chol; Hong, Sungwoo; Jung, Jae Hung; Kim, Hongwook; Kim, Won Tae

We found satisfactory item-own scale correlations (corrected for overlap) in most items, and also found satisfactory internal consistencies for the five scales (except the malaise scale) with Cronbach's alpha ranging from 0.82 to 0.94 (Table 2) . Interestingly, we confirmed satisfactory internal consistency in the bloating and flatulence scale (alpha coefficients ranging from 0.84 to 0.92) at the all three time points, in contrast to the original study with alpha coefficients ranging from 0.49 to 0.62 [8] . However, for the malaise scale, the alpha coefficients were below the 0.70 level (0.26 to 0.44), suggesting heterogeneity of the items in the scale (Table 3) . Similar to our finding, internal consistency of the malaise scale in the original European study was low (0.57 at visit 1, 0.58 at visit 2, and 0.64 at visit 3). We also observed suboptimal item discriminate validity for two items in the malaise scale (item 38 and 39). For example, the item on fever (item 38) correlated more highly with bloating and flatulence scale than with the feeling ill or unwell item (item 39) in its own scale. Item on feeling ill or unwell (item 39) also correlated more highly with other scales, such as urinary symptom, intravesical treatment, future worries, and bloating and flatulence. Very low mean score (floor effect) and non-specificity of the symptom in this scale might be the reason for this finding.