Background: Although the original version of the health-related quality of life (HRQOL) questionnaires are found to be acceptable, the cross-culturally adapted versions may not be comparable to their original version.
Objects: To examine dimensionality and construct validity of two Korean versions of the brief version of the World Health Organization Quality of Life (WHOQOL-BREF) and EuroQOL-5 dimension (EQ-5D) questionnaires.
Methods: A total of 77 cancer survivors undergoing palliative rehabilitation programs from two rehabilitation institutes was recruited from April 16, 2018 to June 26, 2019. The WHOQOL- BREF and the EQ-5D were filled out by the various cancer survivors following a particular session of rehabilitation programs. The scores were analyzed with Winsteps Rasch analysis computer program using the rating scale model. Rasch fit statistics were used to determine the dimensionality and the item difficulty calibrations of WHOQOL-BREF and EQ-5D.
Results: All items except two, negative feeling, need treatment function and pain prevent activity (mean square [MnSq] = 2.42, 1.82 and 2.51, respectively), were found to be acceptable, while two items of the EQ-5D, anxiety/depression and self-care, were misfit (infit MnSq = 1.65 and 0.38, respectively). Item difficulty calibrations of WHOQOL-BREF match person ability measures (i.e., HRQOL) fairly well. However, the person ability distribution showed obvious ceiling effects for EQ-5D. All items of EQ-5D were appeared to be less challenged in comparison with those of WHOQOL-BREF.
Conclusion: Item-level analysis using the Rasch model supports the quality of culturally adapted items used to measure the HRQOL one exception; that is, whether or not to include misfit items as part of the HRQOL measurements. Additionally, cancer survivors undergoing palliative rehabilitation programs appear to have more of a tendency to view the EQ-5D items as being more challenging than the WHOQOL-BREF.

INTRODUCTION
MATERIALS AND METHODS
    1. Subjects
    2. Data Analysis
RESULTS
DISCUSSION
CONCLUSIONS
REFERENCES

• Bong-sam Choi(Department of Physical Therapy, College of Health and Welfare, Woosong University, Daejeon, Korea)