Rasch validation of the SF-36 for assessing the health status of Korean older adults

[Purpose] To verify, using Rasch analysis, the applicability of the 36-Item Short Form Health Survey (SF-36) to elderly Koreans, as this instrument would be useful for determining elderly individuals' overall performance and providing them with health information. [Subjects and Methods] The SF-36 was administered to a sample of 510 individuals aged over 60 living in the Seoul and Gyeonggi areas of South Korea. When testing for goodness-of-fit, we considered items with infit and outfit indexes of over 1.30 or less than 0.70 to be incongruent. SF-36 factors that contained over three items, including physical functioning, role limitations (physical and emotional), mental health, vitality, and general health, were analyzed. Each factor was examined through step calibration of the response categories in the probability curve. [Results] The response categories were found to be appropriate because the adjustment values of each factor increased. We found five items in physical functioning, two items in role limitation-emotion, one item in mental health, and one item in general health to be incongruent; all items in the role limitation-physical and vitality factors were congruent. [Conclusion] We conclude that the SF-36 could be revised to more accurately measure the health status of elderly Koreans.