Construct dimensionality and properties of the categories in the ICF Core Set for low back pain.
OBJECTIVE
The aim of this study was to explore by Rasch analysis whether the Comprehensive International Classification of Functioning, Disability and Health (ICF) Core Set might represent a future clinical tool for measuring functioning of patients with low back pain. Material and methodsThe Comprehensive ICF Core Set for low back pain was scored by health professionals for 118 patients with low back pain. Qualifier levels, invariance, construct validity and ordering of the categories in the components of Body function, Body structure, Activities and participation and Environmental factors were explored by Rasch analysis.


RESULTS
The number of qualifier levels had to be reduced. Categories within Body functions and within Environmental factors reflected a single underlying construct. The categories within the component of Activities and Participation did not meet the requirements of a single underlying construct in the present population. Few categories covered the problems reported by patients with a relatively high level of function.


CONCLUSION
Rasch analysis indicated that the Comprehensive ICF Core Set for low back pain may be used with some modification of categories as a common tool for assessing problems within the components Body functions, and Activity and Participation. However, detecting ICF categories that reflect the higher functional levels in patients with low back pain, and revision of the qualifier levels may be necessary.