Validation and cross-cultural adaptation of the Korean version of the Core Outcome Measures Index in patients with degenerative lumbar disease

Purpose To translate and cross-culturally adapt the Core Outcome Measures Index (COMI) into the Korean language and to test the psychometric properties of the Korean COMI in patients with degenerative lumbar spine diseases. Methods A cross-cultural adaptation of the COMI into Korean was carried out using established guidelines. A total of 117 patients with lumbar spinal diseases were recruited from the spinal center of a tertiary care teaching institution and completed a baseline questionnaire including the newly translated COMI, the visual analog scale for back pain and for leg pain, the Oswestry Disability Index (ODI), and the EuroQOL-5 dimensions (EQ-5D). Within 2 weeks after the first assessment, 83 (71%) completed a second COMI questionnaire and a transition question (no change, slight change, moderate change, a lot of change) by phone to assess reproducibility. Results COMI summary scores displayed 1.7% floor effects and no ceiling effect. For construct validity, each COMI item and COMI summary score well correlated with its corresponding reference questionnaire. Therefore, the predefined hypotheses for the construct validities of each COMI item (>0.4 with the corresponding questionnaire) and the COMI summary score (>0.6 with both ODI and EQ-5D) were confirmed. Intraclass correlation coefficients of each COMI item and summary score ranged from 0.93 to 0.98. Therefore, the hypothesis for reliability (ICC>0.8) was confirmed. Conclusions The present study highlights that the Korean version of the COMI is a reliable and valid outcome tool for use in Korean-speaking patients with degenerative lumbar spinal disease.